Application Note
Version 2
March 2014
Commercial Refrigeration:
Product Selection for Refrigerant Leak Detection Systems
Target Applications: Chiller plants, machine rooms, engine rooms, cold stores, walk in boxes, convenient
stores, supermarkets, and food processing and distribution centers.
Target Refrigerants: HCFs, CFCs, HCFCs, Carbon Dioxide (CO2)
Selecting the appropriate refrigerant leak detector/monitor can be quite a daunting task. There are a number
of products to choose from that vary from different sensing options to various features, and range in pricing
from a few hundred dollars to thousands of dollars.
When selecting a refrigerant monitor, the first thing that should be considered is to determine why a refrigerant
leak detector/monitor is being considered. There are a number of reasons why people use refrigerant leak
detectors/monitors such as:
o
o
o
o
o
Health and Safety of personnel
Reduce refrigerant consumption and costs (Refrigerant Management)
Compliance to Legislation such as
o ASHRAE 15
o F-Gas
o Local building codes
Reduction of energy consumption
Reduced emissions for environmental protection
Based on the desired reason for monitoring, appropriate products and detection technologies should be
evaluated and considered.
Sensing Technology:
When selecting a refrigerant leak detector/monitor the first thing to consider is the sensing technology. There
are three main types of sensors used in refrigerant leak detectors:
o
o
o
Semiconductor; sometimes referred to as solid state,
or metal oxide (MOS) sensors
Infrared diffusion sensors
(gas must permeate to the sensor)
Infrared sampling systems
(gas is pulled to the sensor via a sample pump)
Semiconductor sensors are small devices that consist of a
heated oxide layer that reacts when refrigerant comes in
contact with it. These sensors are fast responding, but not very specific to refrigerants. As with all sensors
there are some disadvantages of using this technology. The following table outlines the advantages and
disadvantages of semiconductor sensors.
Rev 1
1
Application Note
Advantages
Disadvantages
Fast responding
Long life (5-8 years typically)
Lower cost product
Sensitive to a lot of refrigerants
Good for detection of concentrations > 100 ppm
Not very selective
Respond to changes in temperature and humidity
Prone to false alarms <50 ppm
Burn out if exposed to high concentrations
Infrared sensors operate on the principle of infrared absorption. The infrared sensor is made up of an emitter
and detector. Infrared energy is emitted within the same wavelength where the target refrigerant absorbs
infrared energy. As refrigerant passes in between
the emitter and the detector, it will absorb the
infrared energy. There are two types of infrared
sensors, diffusion and aspirated.
A diffusion sensor is a passive sensor that requires
the gas to diffuse into the infrared detection
chamber. These sensors are typically smaller in
size, faster to respond, and are not as sensitive to low concentrations of gas (<15 ppm).
Aspirated sensors, sometimes called sampling systems, are active sensors that utilize a sampling pump to pull
the sample to the sensor. The Bacharach sampling systems have the lowest detection limits (<2 ppm) in the
industry and are available in multiple channels. They are typically more expensive than diffusion infrared
sensors, but in large systems that are looking for small leaks they are the most economical choice.
Advantages
Disadvantages
Fast responding
Long life (8-10 years typically)
Great for low level detection
Very selective to target gas
Damaged by dust and dirt
Expensive
Prone to false alarms <50 ppm
Burn out if exposed to high concentrations
When selecting the product for any application all of these things should be considered. The following table
outlines the various sensors and products.
Semiconductor
Broadband
Infrared
Diffusion
Infrared
Infrared
Sampling
System
Minimum
Detection
Limit
75 ppm
50-70 ppm
5-10 ppm
1 ppm
Cost Per
Point
$300/€218
$750/€545
$1100/€800
$400 (16) - $1650
€290 (16) - €1,200
Wiring
Wiring
Wiring
Tubing
Installation
Compliance Monitors
Refrigerant Management
Bacharach is the only manufacturer that offers a complete line of refrigerant leak detectors to fit all applications
in the refrigeration industry.
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Rev 1
Application Note
Bacharach/Murco Products:
MGD/MGD-100: The MGD-100 product is a standalone refrigerant leak detector system that comes with
remote sensors and a control unit. The MGD-100 can be ordered with 1, 2, 4, or 6 sensors and the controller
can have one (1) or two (2) alarm levels. The controller has alarm LEDs (per channel) as well as a built in
audible alarm and alarm relays. The system has preset alarm levels that activate when the refrigerant gets
above the threshold value.
Typical Application: Engine room, small chiller plant, cold store, walk-in boxes.
MGS/MGS-150: The MGS-150 product is a standalone refrigerant gas sensor capable of monitoring gas
concentrations from 0 – 1000 ppm. The MGS-150 has onboard alarm LED’s, audible alarm, and a single
alarm relay. A user-selectable analog output can be configured as 4-20 mA, 0-5 Volt, 1-5 Volt, 0-10 Volt, 2-10
Volt; allowing the sensors to be connected to a centralized control panel.
*Modbus versions available
Typical Application: Engine room, small chiller plant, cold store, walk-in boxes, convenient stores,
supermarkets.
MGS-250 infrared point detector: The MGS-250 product is a standalone refrigerant gas sensor capable of
monitoring gas concentrations from 0 – 3500 ppm. The MGS-250 is available in either a broadband IR
version, or calibrated specifically for a target refrigerant for increased accuracy. Each unit has an Alpha
Numeric LED display, onboard alarm LED’s, audible alarm, and a single alarm relay. A user-selectable analog
output can be configured as 4-20 mA, 0-5 Volt, 1-5 Volt, 0-10 Volt, 2-10 Volt; allowing the sensors to be
connected to a centralized control panel and a Modbus RTU interface.
Typical Application: Engine room, small chiller plant, cold store, walk-in boxes, convenient stores,
supermarkets.
HGM-MZ: The HGM-MZ product is a standalone infrared refrigerant gas monitoring system. It has onboard
alarm LED’s, audible alarm, alarm relays, and a graphical user interface. A standard Modbus RTU output
allows it to connect to any centralized monitoring panel. Optional output interface cards include 4-20 mA,
BacNet, LonWorks, and N2 Metasys. The unit can be ordered with 4-16 zones depending on the size of the
installation. Because the sensor is infrared, it is ideal for low level detection and refrigerant management
programs.
Typical Application: Engine room, large chiller plants, cold store, walk-in boxes, convenient stores,
supermarkets.
PGM-IR: The PGM-IR portable refrigerant analyzer is the only product on the market proven to analyze and
locate leaks faster than traditional leak detectors. The proprietary infrared sensor allows the unit to display
concentrations as low as 1 ppm, allowing technicians the ability to analyze the surrounding area and track
leaks based on actual concentrations back to the source. The sensor is not affected by changes in
temperature, humidity, or background concentrations of gas, making it the ideal analyzer for reducing leak
rates in facilities.
Rev 1
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Application Note
Compliance vs. Refrigerant Management:
Which type of product do you use? If compliance is of concern, then semiconductor sensors are a logical
choice if they are applied correctly in the application. Semiconductor sensors do respond to a number of
different gases that can be found in the food retail environment, so they are not ideal for low level detection
(refrigerant management) but better suited for gross leak detection. This makes them ideal for finding large
leaks, but they have difficulty finding small leaks on the store floor, in piping runs or display cases.
Gas monitors/analyzers overcome the deficiencies of traditional semiconductor leak detectors because of the
low detection limits of the infrared sensors and non-cross interferences. The Bacharach HGM-MZ
monitor/analyzer utilizes an industry proven infrared sensor that can detect concentrations as low as 1 ppm.
Along with the infrared sensor, the Bacharach HGM-MZ has an onboard LCD display that shows actual
concentrations, in real time. The display makes this monitor/analyzer an invaluable asset when looking for
small leaks.
The benefits of using the HGM-MZ analyzer over a traditional leak detector are:







Find small leaks as low as 1 ppm
LCD Display shows actual concentration in real time
Fast response and clearing times
Can locate leaks on the store floor
Helps the technician prioritize their labor time on fixing the more costly leaks first
Readings are actual concentration – the instrument does not rely on changes in concentration to alarm
Can find small leaks outdoors
Cost of Leaks:
With the costs of refrigerants on the rise, fixing and repairing the smaller leaks pays off. Throughout the
industry, the thought has always been that 80% of the leaks occur in the engine room. The reason for this is
because that is the only place where traditional technologies could find leaks. With newer fixed and portable
analyzers it is now possible to find small leaks outside of the engine rooms. If there are three or four small
leaks that cannot be located on the store floor, they may account for the same refrigerant usage as one large
leak found at the compressor.
Leak rate in
pounds per
month
50
100
200
250
500
50
100
200
250
500
Refrigerant
Type
R22
R22
R22
R22
R22
Cost Per
Pound
$/€
$12.00/€8.70
$12.00/€8.70
$12.00/€8.70
$12.00/€8.70
$12.00/€8.70
Cost of Leak
Per Month
$/€
$600/€435
$1,200€870
$2,400/€1,745
$3,000/€2,180
$6,000/€4,360
Number of months to
Cover continuous
monitor Purchase
11.0
5.5
2.8
2.2
1.1
Number of months
to cover Portable
Analyzer Purchase
6.2
3.1
1.5
1.2
0.6
R404a/R407a
R404a/R407a
R404a/R407a
R404a/R407a
R404a/R407a
$8.00/€5.80
$8.00/€5.80
$8.00/€5.80
$8.00/€5.80
$8.00/€5.80
$400/€290
$800/€580
$1,600/€1,160
$2,000/€1,455
$4,000/€2,910
16.5
8.3
4.1
3.3
1.7
9.3
4.6
2.3
1.9
0.9
Infrared Continuous Monitor
Portable Infrared Analyzer
4
$6,600/€4,800
$3,700/€2,690
Rev 1
Application Note
Real World Cost Analysis:
Bacharach has participated in a number of store surveys to help identify and locate problem leaks that
traditional detectors could not find. At each location the number of pounds of refrigerant that were put into the
system was documented as well as refrigerant type and average cost for that refrigerant. In some instances
two to three small leaks were found, in others 7-10 small leaks were found to be the culprits. The follow chart
shows the data from six different locations.
Case Study
Leak rate in
Pounds per
month
Refrigerant
Type
Cost Per
Pound
$/€
Location 1
Location 2
Location 3
Location 4
Location 5
Location 6
695
48
100
200
400
150
R22
R404a
R404a
R407a
R22
R404a
$12.00/€8.70
$8.00/€5.80
$8.00/€5.80
$8.00/€5.80
$12.00/€8.70
$8.00/€5.80
Cost of Leak
Per Month
$/€
$8,340/€6,065
$384/€280
$800/€580
$1,600/€1,165
$4,800/€3,490
$1,200/€872
Number of
Months to Cover
Continuous
Monitor
Purchase
0.8
17.2
8.3
4.1
1.4
5.5
Number of
Months to
Cover Portable
Analyzer
Purchase
0.4
9.6
4.6
2.3
0.8
3.1
Implementing a Leak Detection Program that Works:
There is not a “cookie cutter” leak detection program that works for everyone. The most effective programs
utilize a mixture of continuous monitors and hand held analyzers. The continuous monitors are placed in key
areas monitoring for leaks 24/7. Portable monitors/analyzers are then used to pin point the leaks so that they
can be repaired. Implementing a program that works for your organization is key to success.
This Application Note is intended to be a guide to help select the right product for the desired application.
More detailed information is available from Bacharach. For additional information on Bacharach products visit
www.MyBacharach.com or www.MurcoGasDetection.com.
  
Bacharach Headquarters:
621 Hunt Valley Circle, New Kensington, PA 15068-7074
Toll Free: 1-800-736-4666 • Tel: +1-724-334-5000 • Fax: +1-724-334-5001
Website: www.MyBacharach.com • E-mail: help@MyBacharach.com
Murco – A Bacharach Company:
114a Georges St. Lr, Dun Laoghaire, Co. Dublin Ireland
+353 1 284 6388
www.MurcoGasDetection.com • E-mail: sales@Murco.ie
Printed in U.S.A.
Rev 1
® Registered Trademark of Bacharach Inc.
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