Health and Safety
Executive
Measurement of acoustic
spectra from liquid leaks
Prepared by Health and Safety Laboratory
for the Health and Safety Executive 2007
RR568
Research Report
Health and Safety
Executive
Measurement of acoustic
spectra from liquid leaks
M Royle
D Willoughby
E Brueck
J Patel
Health and Safety Laboratory
Harpur Hill
Buxton
Derbyshire
SK17 9JN
Acoustic leak detection is being used increasingly in the offshore industry as a means of detecting leaks of flammable
substances on offshore platforms. Rather than relying solely on human intervention or the uncertain and inefficient
dispersion of gas to the detectors, acoustic leak detectors (ALD) detect a leak through the ultrasonic sound produced
by the escaping gas jet. These sensors are generally designed to detect leaks of gaseous products and have been
shown to perform well under the conditions experienced on offshore platforms. HSE recognises the benefits of using
such devices possibly in conjunction with line-of-sight sensors to detect gaseous releases.
This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any
opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy.
HSE Books
© Crown copyright 2007
First published 2007
All rights reserved. No part of this publication may be
reproduced, stored in a retrieval system, or transmitted in
any form or by any means (electronic, mechanical,
photocopying, recording or otherwise) without the prior
written permission of the copyright owner.
Applications for reproduction should be made in writing to:
Licensing Division, Her Majesty’s Stationery Office,
St Clements House, 2-16 Colegate, Norwich NR3 1BQ
or by e-mail to hmsolicensing@cabinet-office.x.gsi.gov.uk
CONTENTS
1.
INTRODUCTION
1
1.1
BACKGROUND
1
1.2
AIMS
1
1.3
THIS REPORT
2
2.
TEST FACILITY
3
2.1
TEST LOCATION
3
2.2
TEST FACILITY
3
2.3
RELEASE FACILITY
4
2.4
FLUID PRESSURISATION VESSELS
5
2.5
RELEASE MANIFOLD
5
3.
INSTRUMENTATION AND DATA PROCESSING
9
3.1
ATMOSPHERIC MEASUREMENTS
3.1.1
Wind speed and direction
3.1.2
Temperature and humidity
9
9
9
3.2
PRESSURE SENSORS
9
3.3
ACOUSTIC LEAK DETECTORS
9
3.4
SOUND MEASUREMENT
11
3.5
DATA ACQUISITION AND ANALYSIS
12
3.6
VISUAL RECORDS
13
4.
WORK PLAN AND OPERATING PROCEDURE
4.1
WORK PLAN
15
4.2
OPERATING PROCEDURE
15
4.3
DATA FILES
16
5.
RESULTS
17
ii
15
iii
iv
5.1
AIR RELEASES
17
5.2
WATER RELEASES
18
5.3
DIESEL RELEASES
22
5.4
PROPANE RELEASES
25
5.5
DIESEL PROPANE MIXTURE RELEASES
28
6.
CONCLUSIONS
31
7.
ACKNOWLEDGEMENTS
33
8.
REFERENCES
35
9.
APPENDICES
36
9.1
Appendix A. Details of Tests undertaken
36
9.2
Appendix B. Frequency spectra
43
9.3
Appendix C Frequency spectra
45
9.4
Appendix D frequency spectra
55
9.5
Appendix E frequency spectra
57
9.6
Appendix F frequency spectra
61
9.7
Appendix G frequency spectra
65
9.8
Appendix H. Details of acoustic equipment used
69
iii
EXECUTIVE SUMMARY
Since the Piper alpha incident in 1988 fixed gas detection systems have proliferated across the
North Sea. However evidence exists to suggest that their contribution to control and mitigation
against major hazards is not in proportion to their size and complexity. This assertion is
supported by data for hydrocarbon leaks and detection methods in the UK offshore industry
over the nine years from 1992 to 2000 (OTO2000/112)(1) The traditional fixed gas detection
systems detect only 65% of flammable gas releases. The remaining 35% of releases are mainly
detected by personnel. Liquid hydrocarbons are much more difficult to detect than gas. From a
total of 793 liquid releases 499 were detected by personnel, i.e. visual sound smell or hand held
metering equipment. The major implication of this is that offshore personnel are entering areas
where hydrocarbon releases exist and that detection of liquid leaks in particular relies on
personnel going into potentially hazardous areas.
Acoustic leak detection is being used increasingly in the offshore industry as a means of
detecting leaks of flammable substances on offshore platforms. Rather than relying solely on
human intervention or the uncertain and inefficient dispersion of gas to the detectors, acoustic
leak detectors (ALD) detect a leak through the ultrasonic sound produced by the escaping gas
jet. These sensors are generally designed to detect leaks of gaseous products and have been
shown to perform well under the conditions experienced on offshore platforms. HSE recognises
the benefits of using such devices possibly in conjunction with line-of-sight sensors to detect
gaseous releases.
There is an increasing desire across the industry to adopt these devices for detection of liquid
releases as well as for gaseous releases. The devices have been proven so far only for gaseous
releases. Acoustic leak detectors have in some circumstances been shown to be able to respond
to the noise generated by liquid releases under pressure. Industry and HSE are however not in a
position to accept the use of these devices for detecting liquid releases because their response to
such leaks has not been characterised.
The aim of this work is to investigate the response of acoustic leak detectors to liquid releases
and ultimately to produce guidance for their acceptable use.
The objectives are to provide:
•
•
•
spectra of the sound produced from pressurised releases of liquids from a variety of
realistic release scenarios,
details of the response of selected ALD sensors positioned at different locations relative
to the point of release and
information which can be used to produce guidance on the use, sensitivity and
positioning of ALD sensors for protection against liquid releases.
The programme of work involved:
•
•
•
Initial releases of air at pressures up to 100 bar in order to characterise the release facility
and provide a base-line sensitivity for the sensors.
Releases of water at pressures up to 100 bar.
Hydrocarbon releases including liquid propane, diesel and diesel / propane mixtures.
iv
v
•
•
•
Releases were made using a variety of release scenarios which were intended to simulate
realistic leakage conditions
Three types of acoustic leak detectors from 2 manufacturers were used for the trials
Acoustic spectra from the releases were recorded.
The data and some discussion of the results are contained in this report. The data, in Excel
format, is given on the accompanying Compact Disc.
Conclusions are provided based on an analysis of the data sufficient only to allow it to be
accurately reported. A more detailed analysis may reveal additional features.
The main conclusions are as follows:
vi
(a)
All releases; air, water, propane, nitrogen padded propane, propane / diesel mixture
or diesel alone gave rise to broadband, random noise into the ultrasonic range.
There are no unique or distinctive frequency characteristics that would identify
either the nature of the opening, the release pressure or the substance released.
(b)
Ultrasonic leak detectors were most effective detecting the air leaks
(c)
The sound pressure level arising from the release changes according to the
substance, the release pressure and the orifice.
(d)
Liquid releases produce a lower sound pressure level than a gas release. An air
release at 32 bar gives rise to level around 30 dB higher than a corresponding water
release. Diesel releases gave levels around 6 dB higher than a water release; mixed
phase releases are around 9 dB higher than a water release.
(e)
Ultrasonic leak detectors will require a higher sensitivity to detect liquid or mixed
phase leaks. The ultrasonic leak detectors used in these trials did not always detect
liquid leaks, even at 98 bar.
(f)
The sound pressure level of the releases increases with increasing release pressure,
although the rate at which the sound pressure level increases against the release
pressure is variable.
(g)
The nature of the orifice affects the sound pressure level. However, the sound
pressure level is not simply related to the orifice size as both increases and
decreases in sound pressure level are reported for increases in size.
(h)
If ultrasonic leak detectors are to be used to detect liquid or mixed phase leaks they
will require a higher sensitivity due to the lower ultrasound levels. However
increasing the sensitivity will only be of benefit if the sound from the leak exceeds
normal background levels. It will not be possible to select any ultrasonic frequency
band that characterises any substance, or opening associated with the leak.
v
1.
1.1
INTRODUCTION
BACKGROUND
Since the Piper alpha incident in 1988 fixed gas detection systems have proliferated across the
North Sea. However evidence exists to suggest that their contribution to control and mitigation
against major hazards is not in proportion to their size and complexity. This assertion is
supported by data for hydrocarbon leaks and detection methods in the UK offshore industry
over the nine years from 1992 to 2000 (OTO2000/112) The traditional fixed gas detection
systems detect only 65% of flammable gas releases. The remaining 35% of releases are mainly
detected by personnel. Liquid hydrocarbons are much more difficult to detect than gas. From a
total of 793 liquid releases 499 were detected by personnel, i.e. visual sound, smell or hand held
metering equipment. The major implication of this is that offshore personnel are entering areas
where hydrocarbon releases exist and that detection of liquid leaks in particular relies on
personnel going into potentially hazardous areas.
Acoustic leak detection is being used increasingly in the offshore industry as a means of
detecting leaks of flammable substances on offshore platforms. Rather than relying solely on
human intervention or the uncertain and inefficient dispersion of gas to the detectors, acoustic
leak detectors (ALD) detect a leak through the ultrasonic sound produced by the escaping gas
jet. These sensors are generally designed to detect leaks of gaseous products and have been
shown to perform well under the conditions experienced on offshore platforms. HSE recognises
the benefits of using such devices possibly in conjunction with line-of-sight sensors to detect
gaseous releases.
There is an increasing desire across the industry to adopt these devices for detection of liquid
releases as well as for gaseous releases, for which the devices have been proven. Acoustic leak
detectors have in some circumstances been shown to respond to the noise generated by liquid
releases under pressure. Industry and HSE are however not in a position to accept the use of
these devices for detecting liquid releases because their response to such leaks has not been
characterised.
1.2
AIMS
This series of experiments was intended to establish whether currently available acoustic leak
detectors could be used successfully to detect liquid leaks. At the same time the acoustic spectra
produced by the leaks would be measured to characterise the sounds produced by high pressure
liquid leaks. This data could then possibly be used to refine sensor performance for liquid leaks.
The aims of the work were to:
(a)
Measure the response of the detectors to leaks of air at pressures up to 100 bar.
(b)
Measure the response of the detectors to leaks of water at pressures up to 100 bar.
(c)
Measure the response of the detectors to releases of diesel and diesel / propane
mixtures at elevated pressure and determine if any difference exists between the
detection of sounds produced by a water leak and those produced by a diesel leak.
(d)
Measure the response of the detectors to a release of liquid propane.
(e)
Characterise the sounds produced from the leaks by means of spectral analysis.
1
1.3
THIS REPORT
This report is a factual record of the tests undertaken and of the measurements recorded. Data
from all the measurements taken are given as Microsoft Excel files on Compact Disk reference
number (HSLPS0618) to allow more detailed analysis.
2
2.
TEST FACILITY
The acoustic leak rig consists of a series of pressure storage vessels and a release rig
interconnected by a flexible hose. Next to the storage unit is a shed which houses the
compressor intended for charging the storage unit with compressed air to the required pressure.
A cylinder of compressed air is used to provide air at 7 bar for the pneumatic valves. Electrical,
instrumentation cables run from the edge of the platform along cable tray to the control room
(building 13). The release of fluids is performed remotely from the control room and all test
parameters can be monitored and logged from the control room.
All solenoid and pneumatic valves are connected in such a way that in the event of either an
electrical or pneumatic supply failure, the system will ‘fail safe’.
In normal operation the area surrounding the rig is observed by video camera.
In normal operation there is no necessity to approach the test facility whilst the apparatus is
under pressure.
This section provides a full description of the acoustic leak release rig.
2.1
TEST LOCATION
The test facility was situated at the gas dispersion site at the Health and Safety Laboratory at
Buxton (see Figure 1).
Gas
d
Dispersion
Fi i Site
New
building
Figure 1. Test location
2.2
TEST FACILITY
The main test facility comprised:
3
•
An elevated steel chequer plate platform, measuring some 10 m x 10 m supported 930
mm above a concrete pad and edged with 50mm high angle section steel;
A three phase multistage air compressor housed next to the platform in a purpose built
building to provide compressed air to the release rig at up to 105 bar;
Three 250 litre vessels to provide storage of release fluids at up to 100 bar;
A buffer vessel and release rig having 5 actuated valves.
Support wire gantry to support the acoustic detectors above the platform
Local wind speed and direction recording (5m from the release point)
Remote control room (100 m from the release point) with data logging equipment,
instrument power supplies and remote control board for the actuated valves.
•
•
•
•
•
•
In the trials described in this report, releases of various fluids were made at pressures up to 100
bar and the outputs from the detectors recorded. The sound produced by these releases was
recorded for later analysis. A schematic representation of the test facility is shown in Figure 2.
High pressure fluid vessels
X
Ultrasonic anemometer
X
Release manifold
Compressor
building
X
Diesel pump
Bulk propane storage
Diesel storage
Concrete block wall
X
Propane release
valve
X
X
Support wires
Nitrogen storage
X
Deck platform
Detector positions
Figure 2. Schematic representation of the test facility
2.3
RELEASE FACILITY
The release facility comprises three discrete items; a Hamworthy high pressure air compressor;
a bank of storage vessels for containing the released fluids and compressed air; and a buffer
vessel and manifold from which the fluids are released. The release facility is controlled
remotely from a building approximately 100 metres distant. This building also houses the
instrumentation power supplies and the data collection equipment.
4
P
I-1
V--1
V--4
PRV--1
P-12--
AV1
V--2
V--3
Air
Water
Diesel
T-1
T-2
T-3
Water fill
Diesel fill
V--6
V--5
V--8
V--7
Air or nitrogen in
V--9
V--10
Flexible hose to release manifold
Figure 3. Piping and instrumentation diagram for storage vessels
2.4
FLUID PRESSURISATION VESSELS
The fluids to be released are stored and pressurised in a bank of three 250 litre steel vessels. The
vessels are pressure tested to 150 bar and are interconnected to allow filling and discharge of the
various fluids. In use the air vessel is pressurised to the required discharge pressure with either
air or nitrogen and the valves on the rig are set such that the required release fluid is forced out
of its storage vessel by the air pressure. The pressure inside the air vessel is monitored using a
pressure transducer. A flexible hose connects the storage vessels to the release manifold. A
piping and instrumentation diagram for the fluid pressurisation vessels is shown in figure 3.
2.5
RELEASE MANIFOLD
The release manifold is fixed to one edge of an elevated 10 x 10 metre deck platform. The
release rig consists of a 22 litre buffer vessel with an inlet and a total of 7 outlets. The outlets
comprise a drain with a manual valve, a bleed facility with a manual valve and five outlets with
full-bore actuated valves for the controlled releases. Each of the five release outlets is fitted with
a pressure transducer immediately upstream of the actuated valve. The outlets from the release
rig were orientated such that the fluids sprayed across the platform. A piping and
instrumentation diagram for the release manifold is shown in figure 4 and a photograph in
figure5.
5
Flexible hose from storage vessels
Vent
PI
V11
V12
Release Manifold / buffer vessel
Drain
AV5
PI
AV6
P
AV4
PI
P
AV3
PI
P
PI
P
AV2
P
PI
Figure 4. Piping and instrumentation diagram for the release manifold.
Figure 5. Release manifold
The release manifold had 5 valves set up to simulate a number of commonly occurring process
fluid leakage scenarios, these are summarised in table 1.
6
Valve Number
1
2
3
4
5
Table 1. Leakage scenarios
Description
Valve stem packing leak (simulating split packing)
Straight hole with varying diameters (3 mm, 12 mm and 24 mm)
Straight hole with 6 mm diameter
Simulating gasket blow out behind a bolt which splits the jet
Simulating gasket blow out between bolts (most common failure)
Gasket blow outs were simulated by removing a section of gasket from the required area of a
raised face 1.5 inch 1500 lb pipe flange. This gave an orifice having a segment shape and
dimensions 31mm x 2mm.
7
3.
INSTRUMENTATION AND DATA PROCESSING
A brief description of the sensors and their location is given in this section.
3.1
ATMOSPHERIC MEASUREMENTS
Atmospheric measurements were necessary in order to correlate differences in acoustic sensor
response.
3.1.1
Wind speed and direction
The wind speed and direction were recorded approximately 10 m from the release point at a
height of 2.5 m using an FT technologies ultrasonic anemometer. Site wind speed and direction
were also recorded at a height of 10 metres using a Vector Instruments A100 anemometer and
weather vane.
3.1.2
Temperature and humidity
The atmospheric humidity was measured at 10 m and 1.5 m using a Vector Instruments
atmospheric humidity sensor. The atmospheric temperature was measured at 1.5 3, 6 and 10
metres using Vector Instruments temperature sensors.
3.2
PRESSURE SENSORS
The conditions within the pressure vessels were monitored using a Vega Controls 0-250 bar
pressure transmitter, similar pressure transmitters were also located upstream of the actuated
valves on each of the five release points. These transmitters are of the strain gauge type having a
stainless steel diaphragm and integrated signal conditioning electronics which give a 4-20 ma
output.
3.3
ACOUSTIC LEAK DETECTORS
The acoustic leak detectors used for these trials were prototype units and therefore became
available at different times during the course of this work. Therefore different combinations of
detectors were used at different times. In initial tests three Innova Gassonic observer detectors
were used, these were supported on poles at 2.8 m above the deck platform, (sensor
configuration A). The initial tests showed that this method of mounting raised questions as to
the levels of ultrasound produced by the jets of fluids impacting the poles and also raised the
possibility of acoustic coupling from the deck platform to the sensors. The mounting of the
sensors was subsequently changed such that they were suspended above the platform on steel
wires. At the same time two additional Innova Gassonic detectors were installed together with a
further detector from Groveley Detection, (sensor configuration B). At a later date a further
Groveley detector was added and one of the Innova Gassonic observers removed, (sensor
configuration C). The first Groveley detector was a broadband unit with an acoustic response
extending into the audible range. The second Groveley detector had a response limited to the
ultrasound region similar to the response of the Gassonic observer detectors. Details of sensor
positions for each configuration are given in table 2 below.
9
Sensor configuration
A
B
C
(1)
(2)
Table 2. Acoustic detector positions
Sensor positions
ALD1
ALD2
ALD3
ALD4
ALD5
ALD6
Gassonic
Gassonic Gassonic
Gassonic Gassonic Gassonic Gassonic Groveley(2)
Groveley(1) Gassonic Gassonic Gassonic Gassonic Groveley(2)
- ultrasonic response detector
– wideband response detector
All the acoustic leak detectors were installed as set up by the manufacturers. The analogue
output from each of the detectors was logged to the data collection system. For both types of
detector this gave an output in decibels. The Gassonic detectors have a baseline threshold level
of 58 dB, that is with no signal detected they read 58 dB. The Gassonic detectors also
periodically produce pulses of ultrasound as an automated self-test, these pulses can be seen on
the spectral analyses of some of the recordings made. The Groveley detectors have a lower
threshold of 10 dB and were scaled to give a reading of between 10 and 100 dB. No alarm
thresholds were set on the detectors as these would, in practice, be set to take account of local
environment and conditions, in order to avoid false alarms. A diagram of detector positions is
shown at figure 6 and a photograph of the detectors mounted above the decking at figure 7.
2m
5
3
4
2
6
1
Release manifold
Release height 0.72 m
above deck
2.5 m
10
2.5 m
m
2.5 m
2.5 m
Figure 6. Detector positions
As noted above, due to the availability of sensors different sensor combinations were used for
different sets of trials, table 2 gives the detector positions for each configuration used.
10
Figure 7. Photograph of the release facility
3.4
SOUND MEASUREMENT
Noise measurements were made between March and November 2005. Weather conditions
varied during measurements over this period. Appendix 1 contains details of the equipment
used to measure the noise generated during the releases. Figures 7 and 8 show the measurement
arrangements.
Two ultrasonic gas leak detectors were tested; the details for each are shown in Table 3.
Table 3: Acoustic specifications for the ultrasonic gas leak detectors
Detector
Gassonic Observer
Acoustic specifications
Detector frequency range:
25 kHz – 70 kHz
Dynamic range:
54 – 104 dB
Groveley Detection GDU-01
Ultrasonic Leak Detector
Groveley Detection wide
band leak detector
Frequency range:
30 – 80 kHz
Frequency range:
3 – 80 kHz
Test sound source
Test frequency:
40 kHz ± 3 kHz
Sound pressure:
100 dB, 60 mm from sound
source
N/a
N/a
Early tests were performed with detector configuration A, as shown in figure 8. Microphones
(connected to preamplifiers via gooseneck extensions) were taped to the posts on which the
11
detectors were mounted approximately 2.6 m above the platform. The microphone diaphragm
was positioned approximately 10 cm from the detector facing the release manifold.
Platform
X Gassonic detector and measurement position
Forward microphone
Left microphone
1
3
2
4
5
Right microphone
Release manifold
Figure 8: Measurement set up for early tests of Gassonics detectors
In later tests, Gassonic and Groveley leak detectors were suspended from wires positioned 2.8
m above the platform as shown in Figure 9. Microphones were taped to the wires so that the
microphone diaphragm was approximately 10 cm from the detector facing the release manifold,
and a third microphone fixed to the release manifold between valves 2 and 3.
Platform
X Measurement position
Groveley detector
Gassonic detector
X
X
1
Left microphone
3
2
4
X
5
Right microphone
Release manifold
Figure 9: Measurement set up for later tests using Gassonic and Groveley detectors
3.5
DATA ACQUISITION AND ANALYSIS
The output from the microphones was input to the TEAC LX-10 data recorder producing a
digital recording with a sample rate of 96 kHz. The data was recorded on magneto-optical discs
for post-processing. The data files were converted into a suitable format that enabled frequency
12
analysis in 94 Hz intervals up to 48 kHz through a MATLAB analysis package. These spectra
are shown as a plot of the power spectral density.
The data files were also played though a band pass filter and measuring amplifier to obtain the
sound pressure level in the one-third-octave band centred at 25 kHz during each release. This
result gives an indication of how the overall level of ultrasound changes with release conditions.
For longer releases a 3 or 10 s exponential averaging time was chosen. For the very short
releases containing diesel the maximum rms level with a fast time constant is reported. Spectra
from early recordings contain tonal spikes. These are purely due to pick up in the recording
system when recording low level ultrasound against higher level audible sound. These spikes
were present both with and without a release and were eliminated in later recordings by careful
earthing of the recording system.
All other instrumentation used had 4-20 mA outputs; these signals were fed back to the data
collection system where they were converted to voltages using precision 250 Ohm resistors. The
data collection system comprised three Data Translation 12 bit 330 kHz analogue to digital
capture cards fitted into a PC and running Agilent Vee data collection software. Multipliers and
offsets were entered into the data collection software to provide an output in engineering units.
3.6
VISUAL RECORDS
Video cameras were used to monitor and record the trials. A digital camcorder was located on
the platform upwind of the release position as far as was possible in the prevailing weather
conditions. A camera was also located on a 10 m mast overlooking the site for general
surveillance.
13
4.
WORK PLAN AND OPERATING PROCEDURE
The work plan and operating procedure are described in this section.
4.1
WORK PLAN
The work plan involved performance of:
(a)
(b)
(c)
(d)
(e)
(f)
Releases of air through each release orifice at pressures of 32 and 98 bar.
Releases of water through each release orifice at pressures of 10, 32 and 98 bar.
Releases of liquid propane at its own vapour pressure.
Releases of liquid propane at approximately 3 bar above its own vapour pressure in
order to ensure it remained liquid at the point of release.
Limited releases of diesel fuel oil to determine if release of this fluid is acoustically
different to water.
Limited releases of diesel fuel oil and propane mixtures containing 5% propane by
weight.
Details of the tests undertaken are given in Appendix 1.
4.2
OPERATING PROCEDURE
The following procedure was used.
(a)
(b)
(c)
(d)
(e)
(f)
The valves on the rig were set to the correct position for the type of test to be
performed.
For liquid releases the requisite vessel was filled with the release fluid.
The release manifold was vented such that the release fluid filled the manifold
The compressor was started and the air reservoir was pressurised to the required
release pressure (for diesel releases this reservoir was pressurised with nitrogen to
avoid any possibility of compression ignition of the diesel).
After making sure the exclusion zone was clear, the data collection system was
started and the required release valve operated.
The data from the instrumentation was recorded and then backed up and stored.
Releases of propane were made by connecting the 2 inch liquid take-off from a two tonne bulk
storage tank to a remotely actuated valve positioned near to the release manifold on the
platform. This valve was fitted with different orifice plates in order to vary the release size. The
release manifold and pressurisation system was not used for propane releases due to the low
temperatures which may have been encountered.
Diesel and propane mixtures were made within the storage vessel by weighing the diesel into
the storage vessel and then injecting the required amount of liquid propane from a liquid takeoff cylinder positioned on a balance.
15
4.3
DATA FILES
Only processed data (i.e. in engineering units), is given in compact disc HSLPS1806. An Excel
spreadsheet was produced for each trial. They were labelled as follows and contained the
following:
Trial name
e.g. ALDAIR01.xls
The files used for the plots given in this report are shown in the heading to each plot.
16
5.
RESULTS
The sound pressure level results are given in tables below. In the release details column the
release orifice and pressure are given together with any other identifying name and number to
enable cross reference to other parts of the report. The file name column refers to the sound
recording file name. The value reported for the 25 kHz third octave band is the unweighted rms
average sound pressure level during the release; the fast rms maximum sound pressure level is
reported for the very short duration releases containing diesel. The corresponding frequency
spectrum is referenced in the final column and can be found in Appendices B to G Frequency
Spectra. Examples of outputs produced by the ultrasonic leak detectors are also given in this
section. The complete data files are supplied on the accompanying Compact Disc
(HSLPS1806).
5.1
AIR RELEASES
Air releases were performed to check the response of the acoustic sensors to the type of releases
they were designed to detect. All the detectors installed for these trials were found to detect air
releases at quite small release rates. An example of the output from these devices in response to
a simulated gasket failure at a pressure of 10 bar is shown in figure 10. Further air releases were
made at various pressures to characterise the response of the devices. A full set of plots for the
air releases performed are shown in appendix B.
Table 4 gives the sound pressure level from the left microphone during the air releases.
Release details
Valve 4 32 bar
Valve 4 98 bar
Valve 5 32 bar
Valve 5 98 bar
Table 4: Air release analysis results (02/03/2005)
25 kHz one-third
File name
Frequency spectrum
octave band level dB
02-03-2005
Leak12.mat
02-03-2005
Leak14.mat
02-03-2005
Leak10.mat
02-03-2005
Leak13.mat
17
97
Figure B1
Recorder overload
Figure B2
Recorder overload
Figure B3
Recorder overload
Figure B4
Air release at 10bar - file ALDAIR11.xls
100
0_16_ALD 1g
0_17_ALD 2
90
Detector response (dB)
80
0_18_ALD 3
end of
release
start of
release
0_20_ALD 5
0_21_ALD 6g
70
60
50
40
30
20
10
0
0
5
10
15
20
25
30
35
40
Time (s)
Figure 10. Detector response to a simulated gasket failure releasing air at 10 bar.
5.2
WATER RELEASES
Water releases were performed in order to determine the response of the acoustic detectors to
liquid releases. The acoustic spectra produced by the releases in the ultrasound region were also
measured. Releases with water were performed at 10, 32 and 98 bar with release orifices of 3,
6, 12 and 25 mm. The acoustic measurements performed showed broadband ultrasound was
produced with no unique or distinctive frequency characteristics. The water releases produced
ultrasound levels approximately 30 dB lower than the air releases with the result that the water
releases were poorly detected. The sensors did produce an output in response to some of the
leaks but it would be difficult to use as a reliable alarm trigger. Figure 11 shows the detector
response for a 3 mm water release at 10 bar; as can be seen the detectors show no response to
this release. Acoustic measurements for this release show a sound pressure level of 64 dB in the
25 kHz third octave band. Figure 12 shows the detector response for a 3 mm water release at 98
bar. Acoustic measurements for this release show a sound pressure level of 71 dB in the 25 kHz
third octave band.
Table 5 gives the sound pressure levels from the left microphone during the water releases.
March and August measurements have been separated as different microphone positions and
test rig arrangements were used. Lower than expected values were reported for the last three
measurements on 10 March; it is possible that water on the microphone windshield has
attenuated the measured sound level.
18
Table 5: Water release analysis results (10/03/2005, 08/08/05 and 09/08/05)
25 kHz one-third octave Frequency spectrum
Release details
File name
band level dB
March measurements
Valve 1 10 bar
10_3_2005
ALDTEST38
L96k9.mat
Valve 1 32 bar
10_3_2005
ALDTEST34
L96k5.mat
Valve 1 98 bar
10_3_2005
ALDTEST42
L96k13.mat
Valve 2 98 bar
10_3_2005
ALDTEST43
L96k14.mat
Valve 3 10 bar
10_3_2005
ALDTEST37
L96k8.mat
Valve 3 (6 mm) 32 10_3_2005
bar ALDTEST33
L96k4.mat
Valve 3 98 bar
10_3_2005
ALDTEST41
L96k12.mat
Valve 4 10 bar
10_3_2005
ALDTEST36
L96k7.mat
Valve 4 32 bar
10_3_2005
ALDTEST32
L96k3.mat
Valve 4 98 bar
10_3_2005
ALDTEST40
L96k11.mat
Valve 5 10 bar
10_3_2005
ALDTEST35
L96k6 .mat
Valve 5 32 bar
10_3_2005
ALDTEST30
L96k1.mat
Valve 5 32 bar
10_3_2005
ALDTEST31
L96k2 .mat
Valve 5 98 bar
10_3_2005
ALDTEST39
L96k10.mat
August measurements
Valve 2 32 bar
9_8_2005
LEAKTEST08
Leak16.mat
66
Figure C1
64
Figure C2
54 (microphone
windshield wet?)
Recorder overload
Figure C3
Not included
65
Figure C4
67
Figure C5
59 (microphone
windshield wet?)
64
Figure C6
67
Figure C8
69
Figure C9
64
Figure C10
67
Figure C11
66
Figure C12
71
Figure C13
66
Figure C14
Figure C7
Valve 3 32 bar
LEAKTEST07
9_8_2005
Leak15.mat
67
Figure C15
Valve 3 100 bar
LEAKTEST09
9_8_2005
Leak17.mat
72
Figure C16
Valve 3 97 bar
LEAKTEST10
Valve 4 32 bar
LEAKTEST06
9_8_2005
Leak18.mat
9_8_2005
Leak14.mat
70
Not included
66
Figure C17
19
Valve 4 100 bar
LEAKTEST04
Valve 5 32 bar
LEAKTEST05
9_8_2005 Leak6.mat
71
Figure C18
9_8_2005
Leak13.mat
59
Figure C19
Valve 5 100 bar
LEAKTEST01
Valve 5 100 bar
LEAKTEST02
Valve 5 100 bar
LEAKTEST03
9_8_2005 Leak3.mat
65
Figure C20
9_8_2005 Leak4.mat
65
Figure C21
9_8_2005 Leak5.mat
65
Figure C22
ALDTEST35.xls. 3mm hole betwween bolts at 10 bar
100
Detector response (dB)
90
ALD1 0_16_ALD 1
ALD2 0_17_ALD 2
80
ALD3 0_18_ALD 3
70
60
50
40
30
20
10
0
0
2
4
6
8
10
12
14
16
Time (s)
Figure 11. Detector response to a simulated gasket failure releasing water at 10 bar.
20
ALDTEST39, water 98 bar, 3 mm hole between flange bolts
100
ALD1 0_16_ALD 1
90
ALD2 0_17_ALD 2
80
Detector response (dB)
ALD3 0_18_ALD 3
start of
release
end of
release
70
60
50
40
30
20
10
0
0
5
10
15
20
Time (s)
Figure 12. Detector response to a simulated gasket failure releasing water at 98 bar.
The difference in sound produced and therefore detector response is well illustrated by the
release leaktest10 shown in figure 13. In this test water was released through a 6mm orifice at
98 bar, the release was allowed to continue until all the water had been used and air started to
come through. When this occurred a step change appeared on the detector outputs. When water
was being released the nearest detector gave an output of 62 dB (4dB above its baseline level),
when air started to be released the output increased to 91 dB. It should be noted that the detector
ALD6g is a wideband response unit, which also responds to audible noise.
21
Leak Test 10
100
Detector response (dB)
90
80
70
60
50
air
40
0_17_ALD 2
0_18_ALD 3
30
0_19_ALD 4
0_20_ALD 5
20
0_21_ALD 6g
start of water
release
10
0
100
200
300
400
Time (s)
Figure 13. Plot showing different response to water and air leaks.
5.3
DIESEL RELEASES
Diesel releases were performed in order to determine if the sound produced by this type of fluid
was significantly different to that produced by water. The acoustic measurements showed
ultrasound levels possibly 6 dB higher than those produced by water but again there were no
unique or distinctive frequency characteristics. The diesel releases only produced broadband
ultrasound. The duration and size of these releases were kept to a minimum to reduce the
environmental impact and clean up required. Figure 14 shows the detector response for a Diesel
release from a between bolt simulated gasket failure at 10 bar, the acoustic measurement on this
release gave a sound pressure level of 69 dB in the 25 kHz third octave band. Figure 15 shows
the detector response for a between bolt diesel release at 98 bar, the acoustic measurement on
this release gave a sound pressure level of 72 dB in the 25 kHz third octave band. The plots
show that the detector having the greatest response to the releases is ALD1 this is due to the
position of this detector – it is nearest to the leak, and is also downwind of the leak source.
Table 6 gives the sound pressure levels from the left microphone during the diesel releases. The
results are reported for very short releases and are the fast rms maximum sound pressure level.
Release details
10 bar valve 5
(between bolts)
ALDDIES 09
10 bar valve 4
(behind bolt)
ALDDIES 10
Table 6: Diesel release analysis results (01/11/2005)
25 kHz one-third
File name
octave band level dB
Frequency
spectrum
01_11_2005
LeakEB16.mat
69
Figure E1
01_11_2005
LeakEB17.mat
69
Figure E2
22
10 bar valve 3 (6mm 01_11_2005
orifice) ALDDIES 11 LeakEB18.mat
68
Figure E3
32 bar valve 5
(between bolts)
ALDDIES 01
32 bar valve 4
(behind bolt)
ALDDIES 02
32 bar valve 5
(between bolts)
ALDDIES 03
32 bar valve 4
(behind bolt)
ALDDIES 04
98 bar valve 3 (6mm
orifice) ALDDIES 05
01_11_2005
LeakEB8.mat
75
Figure E4
01_11_2005
LeakEB9.mat
74
Figure E5
01_11_2005
LeakEB10.mat
67
Figure E6
01_11_2005
LeakEB11.mat
70
Figure E7
01_11_2005
LeakEB12.mat
74
Figure E8
98 bar valve 5
(between bolts)
ALDDIES 06
98 bar valve 4
(behind bolt)
ALDDIES 07
98 bar valve 3 (6mm
orifice) ALDDIES 08
01_11_2005
LeakEB13.mat
72
Figure E9
01_11_2005
LeakEB14.mat
78
Figure E10
01_11_2005
LeakEB15.mat
79
Figure E11
23
ALDDIES09.xls - diesel 10bar between bolts
100
90
0_16_ALD 1g
0_17_ALD 2
start of
release
80
end of
release
0_18_ALD 3
0_19_ALD 4
Detector response (dB)
0_20_ALD 5
70
0_21_ALD 6g
60
50
40
30
20
10
0
0
5
10
15
20
25
Time (s)
Figure 14. Detector response to a simulated gasket failure releasing Diesel at 10 bar.
ALDDIES06.xls - diesel 98bar between bolts
100
0_16_ALD 1g
90
0_17_ALD 2
0_18_ALD 3
Detector response (dB)
80
0_19_ALD 4
end of
release
start of
release
0_20_ALD 5
0_21_ALD 6g
70
60
50
40
30
20
10
0
0
5
10
15
20
25
Time (s)
Figure 15. Detector response to a simulated gasket failure releasing Diesel at 98 bar.
24
5.4
PROPANE RELEASES
Two sets of propane releases were made; one set with propane under its own vapour pressure
and another with the propane vessel pressurised with nitrogen such that the propane would
remain liquid in the nozzle and only flash to vapour when released to the atmosphere. It could
reasonably be anticipated that flashing propane releases, particularly those without nitrogen,
would easily be detected by the acoustic sensors. The spectra obtained by the acoustic
measurements again show the releases gave rise to broadband ultrasound, without any unique or
distinctive characteristics. Figure 16 shows the detector response for a release of propane
through a 3 mm orifice and figure 17 shows the detector response for a release of propane
through a 12 mm orifice. The acoustic measurements for these two tests both give a sound
pressure level of 77 dB in the 25 kHz third octave band but it is apparent from the graphs that
the larger release is more easily detected by the sensors. Figures 18 and 19 show similar releases
but with the propane pressurised with nitrogen.
Table 7 gives the sound pressure levels from the left microphone during the propane releases.
Release details
Table 7: Propane release analysis results (11/08/2005)
25 kHz one-third
File name
Frequency spectrum
octave band level dB
3 mm orifice
ALDPROP04
6 mm orifice
ALDPROP03
12 mm orifice
ALDPROP02
Simulated gasket
failure ALDPROP05
38mm orifice
ALDPROP06
11_08_2005
Leak89.mat
11_08_2005
Leak88.mat
11_08_2005
Leak87.mat
11_08_2005
Leak810.mat
11_08_2005
Leak811.mat
77
Not included
79
Figure D1
77
Figure D2
80
Figure D3
91
Figure D4
Table 8 gives the sound pressure levels measured by the right microphone for each of the
Nitrogen padded propane releases. It should be noted that the microphone to the left of the
release failed during the day’s measurements and the results have been removed from the
corresponding frequency spectra.
Table 8: Propane padded nitrogen release analysis results (17/11/2005)
25 kHz one-third
Release details
File name
Frequency spectrum
octave band level dB
3 mm orifice
ALDPROP08
3 mm orifice
ALDPROP09
6 mm orifice
ALDPROP10
6 mm orifice
ALDPROP11
12 mm orifice
ALDPROP14
12 mm orifice
ALDPROP15
38 mm orifice
8 bar 17_11_2005Leak910.mat 85
Figure F1
8 bar 17_11_2005Leak911.mat 83
Figure F2
8 bar 17_11_2005Leak912.mat 84
Figure F3
8 bar 17_11_2005Leak913.mat 84
Figure F4
8 bar 17_11_2005Leak916.mat 85
Not included
8 bar 17_11_2005Leak918.mat 85
Figure F5
8 bar 17_11_2005Leak919.mat 81
Figure F6
25
ALDPROP16
Simulated
gasket
80
failure ALDPROP12
17_11_2005Leak914.mat
Figure F7
Simulated
gasket
80
failure ALDPROP13
17_11_2005Leak915.mat
Figure F8
ALDPROP04.xls - release of propane through 3mm orifice
100
0_17_ALD 2
90
0_18_ALD 3
0_19_ALD 4
Detector response (dB)
80
0_20_ALD 5
0_21_ALD 6g
70
60
50
40
30
20
10
start of
release
end of
release
0
0
50
100
150
200
Time (s)
Figure 16. Detector response to a release of liquid propane through a 3 mm orifice.
26
ALDPROP01.xls - Release of propane through 12 mm orifice
100
0_17_ALD 2
0_18_ALD 3
90
Detector response (dB)
0_19_ALD 4
80
0_20_ALD 5
70
0_21_ALD 6g
end of
release
start of
release
60
50
40
30
20
10
0
0
20
40
60
80
100
120
140
Time (s)
Figure 17. Detector response to a release of liquid propane through a 12 mm orifice.
ALDPROP09.xls - propane release through a 3mm hole
100
Detector response (dB)
90
80
70
60
50
40
30
0_16_ALD 1g
0_17_ALD 2
20
0_18_ALD 3
0_19_ALD 4
start of
release
10
0_20_ALD 5
0_21_ALD 6g
0
0
5
10
15
20
25
30
35
Time (s)
Figure 18. Detector response to a release of nitrogen padded liquid propane through a
3 mm orifice.
27
ALDPROP15.xls - propane release through a 12mm hole
100
Detector response (dB)
90
start of
release
end of
release
80
70
60
50
40
0_16_ALD 1g
0_17_ALD 2
30
0_18_ALD 3
0_19_ALD 4
20
0_20_ALD 5
0_21_ALD 6g
10
0
0
5
10
15
20
25
30
35
Time (s)
Figure 19. Detector response to a release of nitrogen padded liquid propane through a 12mm
orifice.
5.5
DIESEL PROPANE MIXTURE RELEASES
Releases were made using a mixture of diesel and propane; the mixture contained
approximately 5% propane by mass. This mixture was intended to be representative of a ‘dead’
condensate. The mixture was prepared in the diesel storage tank and forced out of the release
manifold under nitrogen pressure. Figure 20 shows detector response to a release of diesel /
propane mixture at 66 bar through a simulated gasket failure. It can be seen that there is very
little difference between detection of this release and that of diesel alone, although acoustic
measurements suggest that these releases may produce slightly more sound than those for diesel
alone. In addition the acoustic spectra for the diesel propane mixture show only broadband
ultrasound arising from the release. There are no unique or distinctive frequency characteristics.
Table 9 gives the sound pressure levels measured by the right microphone for each of the diesel
+ 5% propane releases. It should be noted that the microphone to the left of the release failed
during the day’s measurements and the results have been removed from the frequency spectra.
The sound pressure levels reported below are for very short releases and are the fast rms
maximum sound pressure level.
Table 9: Diesel + 5% propane mix release analysis results (17/11/2005)
25 kHz one-third
Release details
File name
Frequency spectrum
octave band level
dB
Valve 3 (6 mm
orifice) 32 bar
ALDCONDS11
Valve 3 (6 mm
orifice) 65 bar
ALDCONDS05
17_11_2005Leak930.mat 75
Figure G1
17_11_2005Leak924.mat 85
Figure G2
28
Valve 3 65 bar
ALDCONDS06
Valve 4 31 bar
ALDCONDS09
Valve 4 65 bar
ALDCONDS03
Valve 4 65 bar
ALDCONDS04
Valve 5 34 bar
ALDCONDS10
Valve 5 48 bar
ALDCONDS07
Valve 5 48 bar
ALDCONDS08
Valve 5 66 bar
ALDCONDS01
Valve 5 66 bar
ALDCONDS02
17_11_2005Leak925.mat 84
Figure G3
17_11_2005Leak928.mat 76
Figure G4
17_11_2005Leak922.mat 81 (recorder
overload when
valve closed)
17_11_2005Leak923.mat 81
Not included
17_11_2005Leak929.mat 75
Figure G6
17_11_2005Leak926.mat 77
Figure G7
17_11_2005Leak927.mat 77
Figure G8
17_11_2005Leak920.mat 78
Figure G9
17_11_2005Leak921.mat 78
Figure G10
Figure G5
ALDCONDS01.xls - 66 bar diesel/propane release between bolts
90
0_16_ALD 1g
80
0_17_ALD 2
Detector response (dB)
0_18_ALD 3
0_19_ALD 4
70
0_20_ALD 5
0_21_ALD 6g
60
50
40
30
20
start of
release
10
end of
release
0
0
2
4
6
8
10
12
14
Time (s)
Figure 20. Detector response to a release of diesel / propane mixture.
29
16
6.
CONCLUSIONS
Conclusions are provided based on an analysis of the data sufficient only to allow it to be
accurately reported. A more detailed analysis may reveal additional features.
The main conclusions are as follows:
1. All releases; air, water, propane, nitrogen padded propane, propane / diesel
mixture or diesel alone gave rise to broadband, random noise into the ultrasonic
range. There are no unique or distinctive frequency characteristics that would
identify either the nature of the opening, the release pressure or the substance
released.
Note - Spikes at ultrasonic frequencies in early water release recordings proved
to be due to pick up in the recording system. They were apparent with and
without the release, and on unused channels of the recorder. Careful earthing of
the recording equipment later eliminated the spikes.
2. The sound pressure level arising from the release depends on the substance, the
release pressure, and the orifice.
3. Ultrasonic leak detectors were effective detectors of the air leaks. The sound
pressure level from liquid leaks was often insufficient to enable detection.
4. Within the 25 kHz third octave band an air release at 32 bar is likely to give rise
to a level around 30 dB higher than a water release. The results suggest diesel
releases are giving levels around 6 dB higher than a water release, mixed phase
diesel and propane releases are possibly 9 dB higher than a water release. It is
clear from these results that ultrasonic leak detectors will require a higher
sensitivity to detect liquid or mixed phase leaks.
5. The sound pressure level of the releases increases with increasing release
pressure, although the rate at which the sound pressure level increases against
the release pressure is variable.
6. The nature of the orifice affects the sound pressure level. However the orifice
size alone is not a simple effect as both increases and decreases in sound
pressure level are reported for increases in the orifice size.
7. If ultrasonic leak detectors are to be used to detect liquid or mixed phase leaks
they will require a higher sensitivity due to the lower ultrasound levels. It will
not be possible to select any ultrasonic frequency band that characterises any
substance, or opening associated with the leak.
31
7.
ACKNOWLEDGEMENTS
HSL gratefully acknowledge the assistance received from:
Gassonic A/S
CBISS Ltd
Groveley Detection Ltd
Wormald Fire and Safety Ltd
Shell UK Ltd Exploration and Production.
33
8.
REFERENCES
1.) Health and Safety Executive, Offshore Technology Report OTO 2000 112. Offshore
Hydrocarbon Releases Statistics 2000.
35
9.
9.1
APPENDICES
APPENDIX A. DETAILS OF TESTS UNDERTAKEN
Test
ALDtest04
ALDtest05
ALDtest06
ALDtest07
ALDAIR01
ALDAIR02
ALDAIR03
ALDAIR04
ALDAIR05
ALDAIR06
ALDAIR07
ALDAIR08
ALDAIR09
ALDAIR10
ALDAIR11
ALDAIR12
Table A1. Details of air release trials
Pressure
Leak type
(bar)
Valve 5 (3mm hole
between bolts)
Valve 4 (3mm hole
behind bolts)
Valve 5 (3mm hole
between bolts)
Valve 4 (3mm hole
behind bolts)
Valve 3 (6mm orifice)
Valve 2 (12mm orifice)
Valve 3 (6mm orifice)
Valve 2 (12mm orifice)
Valve 3 (6mm orifice)
Valve 2 (12mm orifice)
Valve 5 (between bolt
gasket failure)
Valve 4 (behind bolt
gasket failure)
Valve 5 (between bolt
gasket failure)
Valve 4 (behind bolt
gasket failure)
Valve 5 (between bolt
gasket failure)
Valve 4 (behind bolt
gasket failure)
Sensor
config.
Data
Appendix
32
A
B
32
A
B
98
A
B
98
A
B
10
14
32
32
98
98
98
C
C
C
C
C
C
C
B
B
B
B
B
B
B
98
C
B
32
C
B
32
C
B
10
C
B
10
C
B
Tests ALDAIR01 to 12 were not recorded for spectrum analysis because the levels of
ultrasound produced by air releases was very high and the releases were easily detected.
36
Test
Table A2. Details of water release trials
Pressure
Sensor config.
Leak type
Data Appendix
(bar)
ALDtest30
ALDtest31
ALDtest32
ALDtest33
ALDtest34
ALDtest35
ALDtest36
ALDtest37
ALDtest38
ALDtest39
ALDtest40
ALDtest41
ALDtest42
ALDtest43
Leaktest01
Leaktest02
Leaktest03
Leaktest04
Leaktest05
Leaktest06
Leaktest07
Leaktest08
Leaktest09
Leaktest10 (note 1)
Valve 5 (3mm hole
between bolts)
Valve 5 (3mm hole
between bolts)
Valve 4 (3mm hole
behind bolts)
Valve 3 (6mm orifice)
Valve 1 (valve
Packing removed)
Valve 5 (3mm hole
between bolts)
Valve 4 (3mm hole
behind bolts)
Valve 3 (6mm orifice)
Valve 1 (valve
Packing removed)
Valve 5 (3mm hole
between bolts)
Valve 4 (3mm hole
behind bolts)
Valve 3 (6mm orifice)
Valve 1 (valve
Packing removed)
Valve 2 (24mm
orifice)
Valve 5 (between bolt
gasket failure)
Valve 5 (between bolt
gasket failure)
Valve 5 (between bolt
gasket failure)
Valve 4 (behind bolt
gasket failure)
Valve 5 (between bolt
gasket failure)
Valve 4 (behind bolt
gasket failure)
Valve 3 (6mm orifice)
Valve 2 (12mm
orifice)
Valve 3 (6mm orifice)
Valve 3 (6mm orifice)
32
A
C
32
A
C
32
A
C
32
32
A
A
C
C
10
A
C
10
A
C
10
10
A
A
C
C
98
A
C
98
A
C
98
98
A
A
C
C
98
A
C
98
B
C
98
B
C
98
B
C
98
B
C
32
B
C
98
B
C
32
32
B
B
C
C
98
98
B
B
C
C
Note 1: For leaktest10 the release of water was continued until the water in the reservoir was exhausted
and air came through.
37
Test
Aldprop01
Aldprop02
Aldprop03
Aldprop04
Aldprop05
Aldprop06
Table A3. Details of liquid propane releases under vapour pressure
Pressure
Sensor config.
Data Appendix
Leak type
(bar)
12mm orifice
7.7
B
D
12mm orifice
7.7
B
D
6mm orifice
7.7
B
D
3mm orifice
7.7
B
D
Simulated failure
7.7
B
D
of 2mm gasket
38mm orifice
7.7
B
D
38
Test
ALDDIES01
ALDDIES02
ALDDIES03
ALDDIES04
ALDDIES05
ALDDIES06
ALDDIES07
ALDDIES08
ALDDIES09
ALDDIES10
ALDDIES11
Table A4. Details of Diesel releases
Pressure
Sensor config.
(bar)
Leak type
Valve 5
(between bolt
gasket failure)
Valve 4
(behind bolt
gasket failure)
Valve 5
(between bolt
gasket failure)
Valve 4
(behind bolt
gasket failure)
Valve 3 (6mm
orifice)
Valve 5
(between bolt
gasket failure)
Valve 4
(behind bolt
gasket failure)
Valve 3 (6mm
orifice)
Valve 5
(between bolt
gasket failure)
Valve 4
(behind bolt
gasket failure)
Valve 3 (6mm
orifice)
Data Appendix
32
C
E
32
C
E
32
C
E
32
C
E
98
C
E
98
C
E
32
C
E
98
C
E
10
C
E
10
C
E
10
C
E
39
Test
ALDPROP08
ALDPROP09
ALDPROP10
ALDPROP11
ALDPROP12
ALDPROP13
ALDPROP14
ALDPROP15
ALDPROP16
Table A5. Details of nitrogen padded propane releases
Pressure
Sensor config.
Leak type
(bar)
3mm orifice
8.4
C
3mm orifice
6.9
C
6mm orifice
7.2
C
6mm orifice
7.2
C
2mm gasket
7.5
C
failure
2mm gasket
7.4
C
failure
12mm orifice
7.5
C
12mm orifice
6.8
C
38mm orifice
7.0
C
40
Data Appendix
F
F
F
F
F
F
F
F
F
Test
ALDCONDS01
ALDCONDS02
ALDCONDS03
ALDCONDS04
ALDCONDS05
ALDCONDS06
ALDCONDS07
ALDCONDS08
ALDCONDS09
ALDCONDS10
ALDCONDS011
Table A6. Details of Diesel + 5% propane releases
Pressure
Sensor config.
Leak type
(bar)
66
C
Valve 5
(between bolt
gasket failure)
Valve 5
(between bolt
gasket failure)
Valve 4 (behind
bolt gasket
failure)
Valve 4 (behind
bolt gasket
failure)
Valve 3 (6mm
orifice)
Valve 3 (6mm
orifice)
Valve 5
(between bolt
gasket failure)
Valve 5
(between bolt
gasket failure)
Valve 4 (behind
bolt gasket
failure)
Valve 5
(between bolt
gasket failure)
Valve 3 (6mm
orifice)
Data Appendix
G
66
C
G
65
C
G
65
C
G
65
C
G
65
C
G
48
C
G
48
C
G
31
C
G
34
C
G
34
C
G
41
9.2
APPENDIX B. FREQUENCY SPECTRA
Air releases 2/3/05
It should be noted that the recorder overloaded during the measurements reported in Figures B2,
B3, and B4. The resultant levels shown are therefore an underestimate of the actual values.
Figure B1 Valve 4 32bar
1
0.1
forward
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 02_03_2005 Leak12.mat 0 to 30s
Figure B2 Valve 4 98bar
1
0.1
forward
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 03_03_2005 Leak14.mat 0 to 45s
43
30000
35000
40000
45000
50000
Figure B3 Valve 5 32bar
1
0.1
forward
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 02_03_2005 Leak10.mat 0 to 46s
Figure B4 Valve 5 98bar
1
0.1
forward
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 02_03_2005 Leak13.mat 0 to 107s
44
30000
35000
40000
45000
50000
9.3
APPENDIX C FREQUENCY SPECTRA
Water releases 10/3/05
The spikes shown in the frequency analysis are due to pick up in the recording system. The
peaks around 40kHz are the sound of the self-test of the leak detectors.
Figure C1 Valve 1 10bar
1
0.1
centre
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 10_03_2005 L96k9.mat 0 to 10s
Figure C2 Valve 1 32 bar
1
0.1
centre
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 10_03_2005 L96k5.mat 0 to 15s
45
30000
35000
40000
45000
50000
Figure C3 valve 1 98 bar
1
0.1
centre
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 10_03_2005 L96k13.mat 0 to 40s
Figure C4 Valve 3 10 bar
1
0.1
centre
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 10_03_2005 L96k8.mat 0 to 16s
Figure C5 Valve 3 (6mm) 32 bar
1
0.1
centre
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 10_03_2005 L96k4.mat 0 to 15s
46
30000
35000
40000
45000
50000
Figure C6 Valve 3 98 bar
1
0.1
centre
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 10_03_2005 L96k12.mat 0 to 14s
Figure C7 Valve 4 10 bar
1
0.1
centre
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 10_03_2005 L96k7.mat 0 to 17s
Figure C8 Valve 4 32 bar
1
0.1
centre
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 10_03_2005 L96k3.mat 0 to 20s
47
30000
35000
40000
45000
50000
Figure C9 Valve 4 98 bar
1
0.1
centre
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 10_03_2005 L96k11.mat 0 to 20s
Figure C10 Valve 5 10 bar
1
0.1
centre
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 10_03_2005 L96k6.mat 0 to 18s
Figure C11 Valve 5 32 bar
1
0.1
centre
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 10_03_2005 L96k1.mat 0 to 13s
48
30000
35000
40000
45000
50000
Figure C12 Valve 5 32 bar
1
0.1
centre
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 10_03_2005 L96k2.mat 0 to 16s
Figure C13 Valve 5 98 bar
1
0.1
centre
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 10_03_2005 L96k10.mat 0 to 17s
49
30000
35000
40000
45000
50000
Water releases 8 and 9/8/05
Spikes shown on the frequency response are due to pick up on the recording system. The peaks
around 40kHz are the sound of the leak detectors self test.
Figure C14 Valve 2 32 bar release 08
1
0.1
behind valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 09_08_2005 Leak16.mat 0 to 27s
Figure C15 Valve 3 32 bar release 07
1
0.1
behind valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 09_08_2005 Leak15.mat 0 to 56s
50
30000
35000
40000
45000
50000
Figure C16 Valve 3 100 bar release 09
1
0.1
behind valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 09_08_2005 Leak17.mat 0 to 53s
Figure C17 Valve 4 32 bar release 06
1
0.1
behind valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 09_08_2005 Leak14.mat 0 to 38s
Figure C18 Valve 4 100 bar release 04
1
0.1
behind valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 09_08_2005 Leak6.mat 0 to 59s
51
30000
35000
40000
45000
50000
Figure C19 Valve 5 32 bar release 05
1
0.1
behind valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 09_08_2005 Leak13.mat 0 to 66s
Figure C20 Valve 5 100 bar release 01
1
0.1
behind valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 09_08_2005 Leak3.mat 0 to 59s
Figure C21 Valve 5 100 bar release 02
1
0.1
behind valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 09_08_2005 Leak4.mat 0 to 49s
52
30000
35000
40000
45000
50000
Figure C22 Valve 5 100 bar release 03
1
0.1
behind valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 09_08_2005 Leak5.mat 0 to 46s
53
30000
35000
40000
45000
50000
9.4
APPENDIX D FREQUENCY SPECTRA
Propane releases (11/08/2005)
Figure D1 6mm orifice
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 11_08_2005 Leak88.mat 0 to 74s
Figure D2 12mm orifice
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 11_08_2005 Leak87.mat 0 to 67s
55
30000
35000
40000
45000
50000
Figure D3 Simulated gasket failure
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 11_08_2005 Leak810.mat 0 to 59s
Figure D4 1.5 inch orifice
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 11_08_2005 Leak811.mat 0 to 44s
56
30000
35000
40000
45000
50000
9.5
APPENDIX E FREQUENCY SPECTRA
Diesel Releases – 1/11/05
As only short releases were made the frequency spectra have been taken from analysis of a
recording segment containing the release. The note below the spectra details the file and period
analysed.
Figure E1 10 bar valve 5 (between bolts) ALDDIES 09
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 01_11_2005 LeakEB16.mat 19 to 20s
Figure E2 10 bar valve 4 (behind bolt) ALDDIES 10
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 01_11_2005 LeakEB17.mat 24 to 25s
57
30000
35000
40000
45000
50000
Figure E3 10 bar valve 3 (6mm orifice) ALDDIES 11
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 01_11_2005 LeakEB18.mat 25 to 29s
Figure E4 32 bar valve 5 (between bolts) ALDDIES 01
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 01_11_2005 LeakEB8.mat 0 to 52s
Figure E5 32 bar valve 4 (behind bolt) ALDDIES 02
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 01_11_2005 LeakEB9.mat 27 to 29s
58
30000
35000
40000
45000
50000
Figure E6 32 bar valve 5 (between bolts) ALDDIES 03
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 01_11_2005 LeakEB10.mat 23 to 25s
Figure E7 32 bar valve 4 (behind bolt) ALDDIES 04
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 01_11_2005 LeakEB11.mat 16 to 19s
Figure E8 98 bar valve 3 (6mm orifice) ALDDIES 05
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 01_11_2005 LeakEB12.mat 19 to 22s
59
30000
35000
40000
45000
50000
Figure E9 98 bar valve 5 (between bolts) ALDDIES 06
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 01_11_2005 LeakEB13.mat 15 to 16s
Figure E10 98 bar valve 4 (behind bolt) ALDDIES 07
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 01_11_2005 LeakEB14.mat 35 to 38s
Figure E11 98 bar valve 3 (6mm orifice) ALDDIES 08
1
0.1
at valves
0.01
right
left
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 01_11_2005 LeakEB15.mat 22 to 25s
60
30000
35000
40000
45000
50000
9.6
APPENDIX F FREQUENCY SPECTRA
Propane padded nitrogen releases 17/11/05
The results from the left microphone have been removed because of drifting of the microphone
sensitivity over the day.
Figure F1 3mm orifice 8 bar ALDPROP08
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 17_11_2005 Leak910.mat 0 to 49s
Figure F2 3mm orifice 8 bar ALDPROP09
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 17_11_2005 Leak911.mat 0 to 49s
Figure F3 6mm orifice 8 bar ALDPROP10
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
61
25000
Frequency (Hz)
TEAC data 17_11_2005 Leak912.mat 0 to 39s
30000
35000
40000
45000
50000
Figure F4 6mm orifice 8 bar ALDPROP11
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 17_11_2005 Leak913.mat 0 to 35s
Figure F5 12mm orifice 8 bar ALDPROP15
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 17_11_2005 Leak918.mat 0 to 34s
Figure F6 38mm orifice 8 bar ALDPROP16
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 17_11_2005 Leak919.mat 0 to 42s
62
30000
35000
40000
45000
50000
Figure F7 Simulated gasket failure 8 bar ALDPROP12
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 17_11_2005 Leak914.mat 0 to 47s
Figure F8 Simulated gasket failure 8 bar ALDPROP13
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 17_11_2005 Leak915.mat 0 to 51s
63
30000
35000
40000
45000
50000
9.7
APPENDIX G FREQUENCY SPECTRA
Diesel plus 5% propane releases 17/11/05
The results from the left microphone have been removed because of drifting of the microphone
sensitivity over the day. The background level is shown in Figure G11.
Figure G1 Valve 3 (6mm orifice) 32 bar ALDCONDS11
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 17_11_2005 Leak930.mat 6 to 7s
Figure G2 Valve 3 (6mm orifice) 32 bar ALDCONDS05
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 17_11_2005 Leak924.mat 49 to 51s
65
30000
35000
40000
45000
50000
Figure G3 Valve 3 65 bar ALDCONDS06
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 17_11_2005 Leak925.mat 9 to 13s
Figure G4 Valve 4 31 bar ALDCONDS09
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 17_11_2005 Leak928.mat 9 to 11s
Figure G5 Valve 4 65 bar ALDCONDS04
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 17_11_2005 Leak923.mat 8 to 10s
66
30000
35000
40000
45000
50000
Figure G6 Valve 5 34 bar ALDCONDS10
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 17_11_2005 Leak929.mat 11 to 12s
Figure G7 Valve 5 48 bar ALDCONDS07
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 17_11_2005 Leak926.mat 18 to 20s
Figure G8 Valve 5 48 bar ALDCONDS08
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 17_11_2005 Leak927.mat 6 to 7s
67
30000
35000
40000
45000
50000
Figure G9 Valve 5 66 bar ALDCONDS01
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 17_11_2005 Leak920.mat 8 to 10s
Figure G10 Valve 5 66 bar ALDCONDS02
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
Frequency (Hz)
TEAC data 17_11_2005 Leak921.mat 34 to 36s
Figure G11 Background level
1
0.1
at valves
0.01
right
PSD (Pa²/Hz)²
0.001
0.0001
1E-05
`
1E-06
1E-07
1E-08
1E-09
1E-10
1E-11
0
5000
10000
15000
20000
25000
Frequency (Hz)
TEAC data 17_11_2005 Leak920.mat 2 to 4s
68
30000
35000
40000
45000
50000
9.8
APPENDIX H. DETAILS OF ACOUSTIC EQUIPMENT USED
Equipment
TEAC LX1-10 (MI P8IO) data recorder
B&K 4226 multifunction acoustic calibrator
Serial Number
107564
B&K 4136 microphone
B&K 2169 preamplifier
B&K 2804 power supply
873753
0990257
761775
B&K 4136 microphone
B&K 2169 preamplifier
B&K 2804 power supply
1252964
761505
761755
B&K 4135 microphone
B&K 2169 preamplifier
B&K 2804 power supply
1890291
418630
684344
B&K 4135 microphone
B&K 2169 preamplifier
B&K 2804 power supply
962448
0990252
684342
B&K 2169 preamplifier
608004
B&K 1617 filter set
B&K 2636 measuring amplifier
69
Published by the Health and Safety Executive
06/07
Health and Safety
Executive
Measurement of acoustic
spectra from liquid leaks
Acoustic leak detection is being used increasingly in the
offshore industry as a means of detecting leaks of
flammable substances on offshore platforms. Rather than
relying solely on human intervention or the uncertain and
inefficient dispersion of gas to the detectors, acoustic leak
detectors (ALD) detect a leak through the ultrasonic sound
produced by the escaping gas jet. These sensors are
generally designed to detect leaks of gaseous products
and have been shown to perform well under the conditions
experienced on offshore platforms. HSE recognises the
benefits of using such devices possibly in conjunction with
line-of-sight sensors to detect gaseous releases.
This report and the work it describes were funded by
the Health and Safety Executive (HSE). Its contents,
including any opinions and/or conclusions expressed, are
those of the authors alone and do not necessarily reflect
HSE policy.
RR568
www.hse.gov.uk