Rev.
01
ECO
Description
Initial draft for comment
Author
ZKhan
Approved
Date
6/5/2015
TESS
Instrument Contamination Control Implementation Plan
Dwg. No. 37-15041
Revision 01
5/Jun/2015
37-15041
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Revision 01
Table of Contents
1.0
1.1
Purpose ................................................................................................................ 1
Scope .......................................................................................................................... 1
2.0
List of Acronyms ................................................................................................. 1
3.0
Definitions ............................................................................................................ 2
4.0
Applicable and Reference Documents .............................................................. 3
5.0
Contamination Control Flow .............................................................................. 4
6.0
Implementation of Contamination Control Requirements ............................... 8
6.1
6.2
6.3
Materials and Equipment Required .......................................................................... 8
Cleanliness Inspection and Monitoring Methods .................................................... 8
Verification and Cleaning Schedules ......................................................................14
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Preface
This is the TESS Instrument Contamination Control Implementation Plan. It describes the
instrument contamination budget and the processes for monitoring and verifying instrument
cleanliness.
Revision 01 is the initial draft for comments.
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1.0 Purpose
The purpose of this document is to describe the TESS instrument contamination budget,
contamination control measures and the processes for monitoring and verifying
instrument cleanliness to meet the contamination requirements laid out in the TESS
Instrument Contamination Control Plan (Document number 37-15040)
1.1 Scope
The implementation of contamination control for the TESS instrument is addressed for
the following phases till delivery of the instrument to Orbital ATK: fabrication, assembly,
and instrument integration and testing. The TESS instrument will undergo processing at
various locations including MIT Kavli Institute for Astrophysics and Space Research
(MKI) building NE83 and MIT Lincoln Labs (LL). This document covers instrument
contamination control implementation at both these facilities. Any contamination control
at vendor facilities will be described in vendor documents.
2.0 List of Acronyms
AI&T
CCE
CCM
CCP
CVCM
ESD
FED-STD
GSE
GSFC
HEPA
IPA
I&T
LL
MIL-STD
MKI
MLI
NVR
PAR
QA
QCM
37-15041
Assembly, Integration and Test
Contamination Control Engineer
Contamination Control Manager
Contamination Control Plan
Collected Volatile Condensable Materials
Electrostatic Discharge
Federal Standard
Ground Support Equipment
Goddard Space Flight Center
High Efficiency Particulate Air
Isopropyl Alcohol
Integration and Test
Lincoln Labs
Military Standard
MIT Kavli Institute for Astrophysics and Space Research
Multi-Layer Insulation
Non-Volatile Residue
Performance Assurance Requirements (Document)
Quality Assurance
Quartz Crystal Microbalance
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TML
TQCM
TVAC
VCS
Total Mass Loss
Temperature-Controlled Quartz Crystal Microbalance
Thermal Vacuum
Visibly Clean Sensitive
3.0 Definitions
Cleanroom
Room in which the concentration of airborne particles is
controlled to specified limits.
Clean Zone
Defined space in which the concentration of airborne particles
is controlled to specified limits. Clean zones are classified in
accordance with IEST-14644, which describes the maximum
number of particles permitted per cubic foot of air.
Contamination Any unwanted material that causes degradation in the desired
function of an instrument or flight hardware.
Contamination Organized action to control the level of contamination.
Control
Fiber
A particle whose length-to-width ratio exceeds 10:1 with a
minimum length of 100 microns.
Gross
Cleaning hardware surfaces to visual inspection standards
Cleaning
Level x per
The cleanliness level defined by a number and/or letter
MIL-STD
designating the particle distribution and molecular cleanliness,
1246
respectively.
Nitrogen
Pressurized flow of clean, dry nitrogen through a system in
Purge
order to displace impurities and reactive species.
Non-Volatile
Soluble material remaining after evaporation of a volatile liquid
Residue
which usually causes degradation in the desired function of an
instrument or flight hardware.
Particle
A small quantity of solid or liquid material with definable shape
or mass with a length to width ratio less than 10:1.
Particle Size
Expressed as the apparent maximum linear dimension or
diameter of the particle.
Precision
A cleaning procedure done in a controlled environment to attain
Cleaning
a specific level of cleanliness. This procedure follows gross
cleaning.
Sensitive
Any surface of flight hardware that must meet a specified
Surface
cleanliness level to ensure the minimum performance levels.
Solvent
Method of cleaning surfaces with a stream of filtered solvent
Flushing
under pressure, which is directed against a surface to dislodge
and rinse away any foreign material.
Solvent
A quantitative method of verifying MIL-STD-1246 molecular
Washes
cleanliness levels by measuring molecular contamination in a
solvent, which was washed over a surface and collected.
Surface
An established level of maximum allowable particulate and/or
Cleanliness
NVR contamination ranging from visibly clean to specific MILLevel
STD-1246 levels (e.g., Level 300A, Level 300B, etc.).
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Swab Sample
Tape Lifts
Vapor
Degrease
Visibly Clean
A qualitative method of identifying contaminants by analyzing
the residue on a solvent-soaked swab that was wiped over a
surface.
A quantitative method of verifying MIL-STD-1246 particulate
cleanliness levels by measuring particulate contamination on a
sample of tape that has come in contact with the surface one
wants to examine. The method is described in ASTM E1216:
Standard Practice for Sampling Surface Particulate
Contamination by Tape Lift.
Item to be cleaned is exposed to heated solvent vapors that
condense on the part and wash away contaminant.
The achievement of a clean surface as seen without optical
aids (except corrected vision) as measured by a specified
method. Three levels of visibly clean (VC) requirements are
defined in JSC-SN-C-0005C
4.0 Applicable and Reference Documents
The applicable and reference documents mentioned in this TESS Instrument
Contamination Control Implementation Plan are listed in Table 1 and Table 2.
Table 1 - Applicable TESS Documents
Document Number
37-10037
37-15040
Document Title
TESS Contamination Control Plan
TESS Instrument Contamination Control Plan
Table 2 - Contamination Control Reference Documents
Document Number
MIL-STD- 1246
JSC SP-R-022A
GSFC-TLS-PR-7324-O 1
ASTM E-595
IES-RP-CC-018-89-T
ISO-14644 – 1-7
FED-STD-209
JSC-SN-C-0005D
37-15041
Document Title
Product Cleanliness Levels and Contamination
Control
Specification Vacuum Stability Requirements of
Polymeric Materials for Spacecraft Applications
Contamination Control Procedures for the Tape Lift
Sampling Surfaces
Methods of Test, Total Mass and Controlled Volatile
Condensable Materials from Outgassing in a Vacuum
Environment
Cleanroom Housekeeping – Operating and Monitoring
Procedures
Cleanrooms and Associated Controlled Environments
Airborne Particulate Cleanliness Classes in
Cleanrooms and Clean Zones
Contamination Control Requirements for the Space
Shuttle Program (NASA)
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JPG 5322.1 Rev. E
PS-3-21
ASTM E 1235-8
ASTM E 1234-07
PS-3-27
Contamination Control Requirements Manual (NASA)
Precision Cleaning [MIT Lincoln Labs document]
Standard Test Method for Gravimetric
Determination of Nonvolatile Residue (NVR) in
Environmentally Controlled Areas for Spacecraft
Standard Practice for Handling, Transporting, and
Installing Nonvolatile Residue (NVR) Sample Plates
Used in Environmentally Controlled Areas of
Spacecraft
Implementation of Contamination Control
Requirements [MIT Lincoln Labs document]
5.0 Contamination Control Budget
A flow chart of the assembly, integration and test (AI&T) process, developed by the
Instrument I&T Manager, is used to elucidate the cleanliness environment and
contamination control actions during each step of AI&T and captured in a table. This is
the basis of maintaining a contamination budget to achieve the requirements set forth in
the TESS Instrument Contamination Control Plan (37-15040). Since the AI&T flow
development is ongoing, a complete flowchart and associated table is out of scope of
this document. However, Figure 1 and Table 3 shows an example of one part of the
AI&T process.
The methods used to achieve contamination control during AI&T are detailed in the
following sections.
Figure 1 - Example AI&T Flow
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Table 3 - Example Contamination Budget
Exposure
Time
Step ID Step Name
Location Environment
LEN-05 Procure Lenses
GL
Scientific
LEN-06 Procure Coatings
GL
Scientific
LEN-10 Inspect lenses
MIT LL
Class 1000
0.5 days
LEN-11 RTV Pads on Lenses
MIT LL
Class 100
7 days
Procure
LEN-12 Barrel/Bezels/Hardware
MIT LL
n/a
n/a
Inspect
LEN-13 Barrel/Bezels/Hardware
MIT LL
n/a
n/a
LEN-14 Paint Barrel/Bezels/Hardware MIT LL
n/a
n/a
Bakeout
LEN-15 Barrel/Bezels/Hardware
MIT LL
n/a
n/a
LEN-16 Lenses into bezels
MIT LL
Class 1000
7 days
LEN-17 Cold cycle bezels
MIT LL
Class 1000
1 day
Bezel modal response
LEN-20 characterization
MIT LL
Class 1000
1 day
LEN-22 Lens Bezels into Barrel
MIT LL
Class 1000
7-14 days
LEN-23 Ambient Interferometry
MIT LL
Class 1000
1 day
Torque and stake all
LEN-25 hardware
MIT LL
Class 1000
0.5 day
LEN-28 Lens assembly complete
MIT LL
n/a
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Exposure
Time
Step ID Step Name
Location Environment
LEN-19 Fabricate Cold Shim
MIT LL
n/a
LEN-29 Ship lens and shim
MIT LL
Cleaned to same precision
level
CAML01
Integrate Lens and Detector
Assembly
MKI
CCD Test Area - Class 1000 5 days
INTERNAL LENSES SEALED
CAML02
Cold Testing - Verify Focus &
Performance
MKI
CAML04
Ship unit MKI to LL
Camera Calibration Area Class 1000
3 weeks
MKI
Install Lens Hood
2 days
CAML05
Vibration Testing
MIT LL
procedure in progress
CAML07
Ship unit LL to MKI
MIT LL
procedure under review
CAML08
TVAC Testing
MIT LL
5 days
15 days
The contamination budget will be maintained by the Contamination Control Lead at MKI.
6.0 Contamination Control Measures
To achieve the contamination control requirements, the following measures are used:
1. Maintenance of clean room environments as described in the TESS Instrument
CCP
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2. Monitoring of component cleanliness as described in the following sections
3. Bakeout of components to limit outgassing on-orbit.
The basic bakeout requirements are described in the TESS Instrument CCP.
However, detailed bakeout procedures have been developed for several
instrument components. These are as follows:

List which things being baked out and link to procedures
4. Cleaning components when necessary, as approved by Contamination Control
Lead at LL, Instrument Lead SE…etc. – link to what?
5. Use of contamination control heaters during thermal vacuum (TVAC) testing
Finally, a special contamination control measure is to install contamination
control heaters on the instrument cameras for use during TVAC testing. During
TVAC testing, when the temperature of the chamber is raised after a test, the
heaters are used to raise the temperature of the exposed optics faster so that
they are not the coldest item in the chamber thus preventing contaminants from
migrating to their surfaces. These heaters are described in Section 8.0.
7.0 Verification of Contamination Requirements
To verify the requirements laid out in the TESS Instrument Contamination Control Plan
(37-15040), the cleanliness of components will be monitored in various ways.
A. In general, components will be subject to a light inspection (described in the
following section) at the following events:
1. Upon receipt from another facility
2. Before shipping to another facility
3. Before the start of a test
4. After the end of a test
The results of these inspections will be logged.
B. The NVR cleanliness levels for optical components will be calculated for each
AI&T step using the NVR deposition rates at the facility, measured with methods
defined in Section 8 and the exposure times of the components during the step.
The optical components will be assumed to have zero NVR deposition at the
start of integration and test processing at MIT Lincoln Labs and MIT Kavli
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Institute (NE-83) i.e. they will be assumed to arrive completely clean from the
manufacturer. During each step of AI&T, the environmental conditions and
exposure time of the components will be logged.
C. As a backup, witness plates will follow the instrument cameras during AI&T to log
cumulative particulate and NVR contamination levels. These will be analyzed as
needed, determined by the Contamination Control Leads at LL and MKI.
8.0 Implementation of Contamination Control Measures and
Verification
8.1 Materials and Equipment Required
In clean area:
 Exhaust hood- for flushing plates and other samples
 Tongs- Precision cleaned laboratory type
 Clean glass bottles- grade suitable for residue analysis
 Full-face protective splash-shield
 Beakers – assorted sizes (500, 1000 ml)
 Glass Funnel- approximately 6 inch diameter
 Aluminum Foil – Clean (400-1821)
 Gloves- cleanroom approved nitrile
 Isopropanol- high purity, residue less than 1 ppm
 UV Lamp- at least 100 watts
 Bright White Light Lamp-greater than 200 candle power
 Glass Syringe- 20 ml
On instrument:
 Contamination Control Heaters: Set of three 10 W kapton heaters, mounted on
each camera, measuring 0.5” x 2” wired in parallel controlled by a single power
supply. Link to design description?
8.2 Cleanliness Inspection and Monitoring Methods
6.1.1 Non-volatile Residue (NVR) Monitoring
NVR is monitored in the clean work area where devices are built by two methods: a.
Witness Plate and, b. Surface Acoustics Micro-balance (SAWM).
a.
Witness Plates: An outside analytical laboratory, similar to Balazs
Analytical Services is used to provide pre-measured wafers to be placed in the work
area, where devices are assembled. These wafers are kept for all the time the assembly
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is carried out. The wafers are returned for the NVR analysis to the laboratory at an
interval that is decided by the project manager. Witness plates are shown in the Figure
2. This method is used both at Lincoln Labs and the MIT Kavli Institute (NE-83).
NE83 as well. Do a basic fallout level.
b.
Surface Acoustics Wave Micro-balance (SAWM): A real time non-volatile
residue monitor, a SAWM device is utilized to monitor the NVR buildup continuously in
the area the device is assembled. Currently, Aim-200 Non-Volatile Residue Monitor,
manufactured by Particle Measuring Systems, is used for the NVR monitoring. It could
be replaced by any comparable device. SAWM device has a sensitivity of 3.2 pg/cm2/Hz.
A typical NVR accumulation graph is shown for the deposition over a period of one
month in Figure 3. The NVR monitoring unit is shown on the work bench in Room I-209
at Lincoln Labs. This monitoring method is only used at Lincoln Labs.
c.
Flush Method: NVR on Space Hardware (If a test is required on the
actual parts.)
Warning
Any potential adverse effect on the part due to attack by
solvents should be evaluated before using this test on the space hardware.
A test method, similar to the one described in the ASTM E 1235-08 is used for the NVR
test on the space hardware. The ASTM test method describes the use of a witness
plate. However, for this test, procedure described in this section is used on the actual
parts.
Note
All the glass containers are precision cleaned according to PS-3-21
before using for this test. The beakers and other equipment should be
covered with oil-free aluminum foil, if stored for more than 4 hours.
Fed. Spec. Food Service Grade aluminum foil, oil-free, Federal Stock
No. 8135-00-724-0551 has been found to be satisfactory.
(1)
The part is inspected for the particulate cleanliness, as per the requirement,
following the process in Section 4.1.3.
(2)
Select the surface to be sampled. The surface should be representative of the
item being tested. That is, it should include flat areas, welds, holes, threads, etc., if they
are part of the item. The results will be reported in square feet therefore it is necessary
to record the size of the area sampled.
(3)
Select a surface of the part to be flushed with a known quantity (typically 100
ml/sf) of a high purity solvent. High purity grade (residue less than 1 ppm) isopropyl
alcohol, or methylene chloride is recommended for this test. Methylene chloride is
preferred solvent, if does not react with the article being tested. The certificate of
analysis for the solvent should confirm the residue level below 1 ppm.
(4)
Use proper protective equipment at all the time, for example splash-shield and
gloves.
(5)
Minimum surface area requirements for the NVR test are presented in the Table
1.
(6)
Flush the surface from top to bottom and side-to-side several times and collect
the runoff in the clean container. Ensure that the entire sample area is thoroughly
flushed.
(7)
Control sample of the solvent should be exposed to all operations and
procedures except the actual flushing of the surface being tested. Normally, the same
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amount of solvent is used in the control sample as used to flush the surface being
sampled. The level measured during the control test should be no more than 10% of the
allowable value from the item being tested. The results of the control are to be backed
out of the measured values.
(8)
All the solvent after the rinsing should be collected in a clean bottle, suitable for
the organic residue analysis. The clean bottles should be rinsed with 20 ml of the high
purity grade solvent, same as used for the test. The bottle should have proper label.
(9)
Collected samples should be properly packaged and shipped for the NVR
analysis to be conducted by Balazs Analytical Services*, or, other approved laboratory.
Always include a control sample (100 ml, or, the same quantity used for the sample
flush) of the solvent used for the NVR rinse.
(10) In case, the sample fails, have the sample cleaned a second time. If it still fails,
contact Contamination Control engineering for resolution.
(11) Complete the NVR Test Form provided in the Appendix of this document.
(*Balazs Analytical Services, 46409 Landing Parkway, Fremont CA 94538 Phone: 510624-4000)
Table 4 Minimum Surface Area Required
Minimum Surface Area Required based on solvent NVR background (column C)
and based on the sensitivity of the balance (column D)
A
B
C
D
1246C
Level
Maximum
allowable NVR
per 0.1m2
Definition of a Small Part
Area Anything Less Than:
Minimum Surface Area
Required
A/10
0.1 mg
1000 cm2 (155.0 in2) (1.1 ft2t)
200 cm2 (31.0 in2) (.22 ft2)
A/5
0.2 mg
500 cm2 (77.5 in2) (.54 ft2t)
100 cm2 (15.5 in2) (.11 ft2)
A/2
0.5 mg
200 cm2 (31.0 in2) (.22 ft2t)
40 cm2 (6.2 in2) (.043 ft2)
A
1.0 mg
100 cm2 (15.5 in2) (.11 ft2t)
20 cm2 (3.1 in2) (.022 ft2)
B
2.0 mg
50 cm2 (7.8 in2) (.065 ft2t)
10 cm2 (1.6 in2) (.01 ft2)
C
3.0 mg
33.3 cm2 (5.2in2) (.033 ft2t)
7 cm2 (1.1 in2) (.008 ft2)
There are three distinct groups based on sample-sizes:
a.
Parts with a surface area greater than column C of Table 1 should be
verified per this work instruction.
b.
Parts with a surface area between the values in column C and column D of
Table 1 should be verified per this work instruction with 30 mL of solvent and a control of
30 mL of solvent.
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c.
Parts with a surface area less than column D of Table need special
considerations.
6.1.2 Particle Monitoring
Particles in the Clean Room are monitored by: a. Particle Counters, b. Witness Plates
a.
Particle Counter
Particles in the Lincoln Labs Clean Room I-209 and I-214 are continuously measured by
particle counter, LASAIR II 310A manufactured by Particle Measuring Systems. These
clean rooms are maintained at Class 10,000 (FED-STD-209). The work benches in
these clean rooms are laminar flow type maintaining a cleanliness level of Class 100.
Particles in the MKI Clean Tents in NE83 are monitored by the following particle
counters: HandiLaz Mini manufactured by Particle Measuring Systems and Met One 273
A-B by Beckman Coulter. These clean tents are maintained at Class 1000 (FED-STD209) with laminar flow workbenches maintaining a cleanliness level of Class 100.
b.
Witness Plates for Particulates
Clean polished 6 inch diameter silicon wafers are used as witness plates to determine
particulate fall out rate in the work area. Typically, particles on these wafers are
measured at 2 weeks intervals using a Surfscan 5000 unit manufactured by KLA Tencor.
This provides particle size distribution over a selected particle size range. Measurements
from this unit are used to verify the specified level of cleanliness requirements (as per
standard MIL-STD-1246). In case the particulate level on the witness plate does not
meet the cleanliness requirements, the hardware should be cleaned to bring it in
compliance.
In many instances, a few large particles that have fallen on the surface, once cleaned,
bring the surface in compliance with the requirements. Cumulative fallout of particles for
periods of 3 weeks is shown in the Figure 4.
6.1.3 Light Inspections
Visual inspection is done using black (UV) light or white light. The requirements of the
Visually Clean Levels (VC-I to VC-IV) are given in Table 5. Visibly clean, using white
light is the absence of all particulates and non-particulates visible to normal unaided eye
(except corrected vision). UV inspection light source should be no less than 100 watts
and during inspection should not be more than 18 inch from the inspected item. During
UV inspection light from other sources should not be more than 5 ft-candles. If visual
contamination is present, the hardware must be cleaned and then re-inspected under
the same light conditions. If during UV inspection there is any evidence of fluorescence
(presence of an organic contaminant) the item or surface must be re-cleaned. If recleaning does not reduce the fluorescence, it should be determined whether the
fluorescing material is a contaminant or the substrate surface.
Inspections for verifying cleanliness Levels 500 to 1000, or VC-I and VC-II, the above
inspection method is adequate. Inspection for Levels 200 to 300 should be conducted
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using a 3X magnifier in addition to the bright and UV light sources. For the verification of
Levels 50 to 100 a 10X magnifier is recommended.
As an example, once a surface is inspected with a 3X magnifier using the bright light and
UV light, and all the particles visible (~ 10 to 15 microns and larger) are removed, the
surface will meet the cleanliness Level 200 requirements.
Table 5 - Visually Clean Levels [Ref: A. C. Tribble, Fundamentals of Contamination Control.
Bellingham, Wash: SPIE Optical Engineering Press, 2000.]
Level
Illumination
(ft -candles)
Inspection
Distance
Magnification
UV
Light
Resolution
Limit (µm)
Standard
VC-I
50
5-10 ft
1
no
600-1200
Sensitive
VC-I1/2
50
2-4 ft
1
no
240-480
Highly Sensitive
VC-II
100
6-18 in
1
no
60-180
Highly Sensitive
VC-III
100-200
6-18 in
1
no
10-90
Highly Sensitive
VC-IV
100-200
6-18 in
2-7
yes
~10
Notes
37-15041
(1)
One-foot candle (lumens per square foot) is equivalent to 10.76 lumens per
square meter.
(2)
Cleaning is required if the surface in question does not meet VC under the
specified incident light and observation distance conditions.
(3)
Exposed and accessible surfaces only.
(4)
Initial cleaning is mandatory; Note (2) applies thereafter.
(5)
Areas of suspected contamination may be examined at distances closure than
specified for final verification.
(6)
The notes which apply to each VC levels are:
Standard:
(2) (3) (5)
Sensitive:
(2) (3) (5)
Highly Sensitive:
(3) (4)
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Figure 2 Witness Plates and Aim-200 SA WM Monitor on the Workbench in I-209 Room
Figure 3 NVR Accumulated Over Two Months
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Figure 4 Cumulative Particles on a 6 inch Diameter Witness Wafer Over 2 Week Periods
8.3 Verification and Cleaning Schedules
Cleanliness verification and monitoring will occur at a frequency decided by the
Contamination Control Leads at LL and MKI, others?. If the contamination levels on the
hardware exceed the cleanliness requirements, a cleaning will be scheduled. The
cleanings will be performed by the trained and qualified technicians following the
process outlined in the Lincoln Laboratory Process Specification PS-3-.21.
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APPENDIX A
A1
CLEANLINESS LEVELS
Surface Cleanliness Levels
* Table 6 data from IEST-STD-CC1246D, Table 1.
*From NASA JSC-SN-C-005 Rev. D, Tables A.1 and A2)
Table 6 Surface Cleanliness Levels
Cleanliness
Level
Particle
Size (µm)
Maximum allowable concentration limits for particles of stated
size and larger
Particles per 0.1m2 of surface area or 0.1 liter of gas or liquid
(N)
2
53.1
5
22.7
15
3.3
25
1
5
166
15
24.6
25
7.2
50
1
5
1780
15
264
25
78.4
50
10.7
100
1
15
4180
25
1230
50
169
100
15.8
25
50
100
200
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300
200
1
25
7450
50
1020
100
95
250
2.2
300
1
50
11800
100
1090
250
26.3
500
1
50
95800
100
8910
250
213
500
8.1
750
1
100
42600
250
1020
500
38.7
750
4.7
1000
1
500
750
1000
Example: Level 300 would be particulate level 300. Level 300 C would be particulate level 300
plus NVR level C.
NVR (Nonvolatile Residue) Levels
37-15041
Level
Maximum Quantity NVR Per 0.1 Square
Meters
A
1 mg.
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B
2 mg.
C
3 mg.
D
4 mg.
Notes (1)
37-15041
Inspection criteria shall be specified at the discretion of the
procuring agency. In the event that cleaning is necessary to
achieve the GC level, evidence that cleaning was performed will
constitute verification of GC level.
(2)
Inspection criteria shall be specified at the discretion of the
procuring agency. Refer to Table A.2 for inspection criteria
options that are applicable for the Orbiter payload (cargo) bay,
payload canister, and payloads during Space Shuttle
Orbiter/payload integrated operations at launch and landing
sites.
(3)
Particulate and NVR allowables are based on 0.1 square meters
(1 square foot) of surface area. Flush fluid quantity for sampling
shall be 100 milliliters per 0.1 square meters (1 square foot) of
surface area. Small parts should be grouped together to obtain
0.1 square meters (1 square foot) of surface area. For
determination of NVR fallout in environmentally controlled areas,
see Paragraph 2.4.
(4)
Maximum quantity per 1.0 standard cubic meter (35 standard
cubic feet) of effluent gas when systems are being evaluated by
purging. If feasible, the sampling must be accomplished at a
maximum system operational flow rate.
(5)
Unlimited means particulate in this size range is not counted;
however, if the accumulation of this silt is sufficient to interfere
with the analysis, the sample shall be rejected.
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A2
Visual Cleanliness Levels
GC
Generally Clean (1)
Freedom from manufacturing residue, dirt, oil, grease,
processing debris or other extraneous contamination.
This level can be achieved by washing, wiping, blowing,
vacuuming, brushing, or rinsing. The GC level shall not
be designated for hardware that is sensitive to
contamination.
VC
Visibly Clean (2)
The absence of all particulate and non particulate
matter visible to the normal unaided (except corrected
vision) eye. Particulate is identified as matter of
miniature size with observable length, width, and
thickness. Nonparticulate is film matter without definite
dimension. This level, with the exception of the Orbiter
payload (cargo) bay, payload canister and payloads,
requires precision cleaning methods, but no particle
count.
VC + UV
Visible Clean Plus
Ultraviolet (2)
Visibly clean (as defined above) and inspected with the
aid of an ultraviolet light (black light) of 3200 to 3800
Angstroms wavelength (3.2 x 10-7 TO 3.9 x 10-7
meters).
Note
37-15041
Any evidence of fluorescence shall be cause for recleaning. If
recleaning does not reduce the fluorescence, an investigation
shall be made to determine whether the fluorescing material is
contamination or the basic materials. This level requires
precision cleaning methods, but no particle count.
18
Revision 01
A3
Visibly Clean (VC) Levels and Inspection Criteria
Three levels of VC requirements are available for the Orbiter payload (cargo) bay,
payload canister and payloads during Space Shuttle Orbiter/payload integrated
operations at launch and landing sites. VC STANDARD is baseline as referred to in
contractual documentation. The VC definition in Table A.1 is applicable to this table with
the understanding that incident light levels and inspection distances are specified herein:
Table 7 VC Levels and Inspection Criteria for the Orbiter Payload (Cargo) Bay, Payload Canister, and
Payloads
VC Level
Incident Light Level
(1)
Observation
Distance
Remarks
Standard
> 50 foot-candles
5 to 10 feet
(2) (3) (5)
Sensitive
> 50 foot-candles
2 to 4 feet
(2) (3) (5)
Highly Sensitive
> 100 foot-candles
6 to 18 inches
(3) (4)
Notes
37-15041
(1)
One-foot candle (lumens per square foot) is equivalent to 10.76
lumens per square meter.
(2)
Cleaning is required if the surface in question does not meet VC
under the specified incident light and observation distance
conditions.
(3)
Exposed and accessible surfaces only.
(4)
Initial cleaning is mandatory; Note (2) applies thereafter.
(5)
Areas of suspected contamination may be examined at distances
closer than specified for final verification.
19
Revision 01
Cleanliness Verification Form
Program Name: ____________________________________
Date: ______________________________________
Part No.: _____________________________
Hardware Description: ________________________________________________________________
Inspection Area: _____________________________________________________________________
Required Cleanliness Level (as per document):
__________________________________________________________________________________
1.
Particulate
Standard
2.
Sensitive
Highly Sensitive
Non-volatile Residue
_________ ng/cm2
Inspection
a. Particulate
VC Level
Incident Light Level
UV
Observation
Distance
Recommended
Standard
> 50 footcandles
Yes
No
yes
Sensitive
> 50 footcandles
Yes
No
Yes No 2 to 4 feet
Highly
Sensitive
> 100
footcandles
Yes
No
Yes No 6 to 18 inches
Actual
Distance
Particulates
Present
No 5 to 10 feet
b. NVR
1.
Witness Plates
_______ ng/cm2
2.
Surface Acoustic Wave
Microbalance(SAWM)
_______ ng/cm2
Inspection Results
Particulate
37-15041
Passed
Failed
20
Revision 01
Film
Present
Cleanliness
NVR
Passed
Failed
Remarks
Inspector:
Contamination Control Engineer:
NVR Test Form
Date:
Time
Test Location:
Sample
Number:
Part Number
Temperature:
Humidity:
Solvent NVR from C of A
Mass of solvent used for test
g
Area of the part rinsed
Cm2
Number of samples sent to outside laboratory:
37-15041
21
Revision 01
Operator
Engineer:
NVR Results from the Laboratory*
NVR Requirements
micro-gram/cm2
Level:
NVR Measured
Passed
Failed
Verification Signatures
Contamination Control Engineer:
Date:
*Balazs Analytical Services, 46409 Landing Parkway, Fremont CA 94538
Phone: 510-624-4000
37-15041
22
Revision 01
Cleanliness Verification Form
Program Name:
Date:
Part No.:
Hardware Description:
Inspection Area:
Required Cleanliness Level (as per document):
1.
Particulate
Standard
2.
Sensitive
Highly Sensitive
Non-volatile Residue
ng/cm2
Inspection
a. Particulate
VC Level
Incident Light Level
UV
Standard
> 50 footcandles
Yes
No
Yes
Sensitive
> 50 footcandles
Yes
No
Yes
Highly
Sensitive
> 100 footcandles
Yes
No
Ye
s
No
N6
o
t
o
1
8
i
n
c
h
e
37-15041
23
Obser
Actual
P
Film
vation
a
Present
Distan Distance r
5 to 10 feetce
t
Recom
i
mende
c
N
d
u 2 to 4 feet
o
l
a
t
e
s
P
r
e
s
e
n
t
Revision 01
s
b. NVR
1.
Witness Plates
ng/cm2
2.
Surface Acoustic Wave
Microbalance(SAWM)
ng/cm2
Inspection Results
Particulate
Cleanliness
NVR
Passed
Failed
Passed
Failed
Remarks
Inspector
:
37-15041
Contamination Control Engineer:
24
Revision 01