ASTM E1235-12(2020)
(Test Method)Standard Test Method for Gravimetric Determination of Nonvolatile Residue (NVR) in Environmentally Controlled Areas for Spacecraft
Standard Test Method for Gravimetric Determination of Nonvolatile Residue (NVR) in Environmentally Controlled Areas for Spacecraft
SIGNIFICANCE AND USE
5.1 The NVR determined by this test method is that amount that can reasonably be expected to exist on hardware exposed in environmentally controlled areas.
5.2 The evaporation of the solvent at or near room temperature is to quantify the NVR that exists at room temperature.
5.3 Numerous other methods are being used to determine NVR. This test method is not intended to replace methods used for other applications.
SCOPE
1.1 This test method covers the determination of nonvolatile residue (NVR) fallout in environmentally controlled areas used for the assembly, testing, and processing of spacecraft.
1.2 The NVR of interest is that which is deposited on sampling plate surfaces at room temperature: it is left to the user to infer the relationship between the NVR found on the sampling plate surface and that found on any other surfaces.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: E1235 − 12 (Reapproved 2020)
Standard Test Method for
Gravimetric Determination of Nonvolatile Residue (NVR) in
Environmentally Controlled Areas for Spacecraft
This standard is issued under the fixed designation E1235; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Rooms Using Instruments Capable of Detecting Single
Sub-Micrometre and Larger Particles
1.1 Thistestmethodcoversthedeterminationofnonvolatile
residue(NVR)falloutinenvironmentallycontrolledareasused 2.2 ISO Standards:
for the assembly, testing, and processing of spacecraft. 14644-1 Cleanrooms and Associated Controlled
Environments—Part 1: Classification of Air Cleanliness
1.2 The NVR of interest is that which is deposited on
14644-2 Cleanrooms and Associated Controlled
sampling plate surfaces at room temperature: it is left to the
Environments—Part 2: Specifications for Testing and
user to infer the relationship between the NVR found on the
Monitoring to Prove Continued Compliance with ISO
sampling plate surface and that found on any other surfaces.
14644-1
1.3 This standard does not purport to address all of the
14951-3 Space Systems—Fluid Characteristics—Part 3: Ni-
safety concerns, if any, associated with its use. It is the
trogen
responsibility of the user of this standard to establish appro-
2.3 U.S. Federal Standard:
priate safety, health, and environmental practices and deter-
FED-STD-209E Airborne Particulate Cleanliness Classes in
mine the applicability of regulatory limitations prior to use.
Cleanrooms and Clean Zones
1.4 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this 2.4 Institute of Environmental Sciences and Technology:
standard.
IEST-RP-CC001.3 HEPA and ULPA Filters
IEST-RP-CC007.1 Testing ULPA Filters
1.5 This international standard was developed in accor-
IEST-RP-CC034.1 HEPA and ULPA Filter Leak Tests
dance with internationally recognized principles on standard-
IEST-STD-CC1246 Product Cleanliness Levels and Con-
ization established in the Decision on Principles for the
tamination Control Program
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
2.5 American National Standards Institute:
Barriers to Trade (TBT) Committee.
ANSI/ASME B46.1-2009 Surface Texture (Surface
Roughness, Waviness, and Lay)
2. Referenced Documents
2.6 Other:
2.1 ASTM Standards:
Industrial Ventilation, A Manual of Recommended Practice,
D1193 Specification for Reagent Water
Latest Edition
E1234 Practice for Handling, Transporting, and Installing
SMC-TR-95-28, Nonvolatile Residue Solvent Replacement,
Nonvolatile Residue (NVR) Sample Plates Used in Envi-
U.S. Air Force Space and Missile Systems Center, 1
ronmentally Controlled Areas for Spacecraft
March 1995
F50 Practice for Continuous Sizing and Counting of Air-
borne Particles in Dust-Controlled Areas and Clean
3. Terminology
3.1 Definitions:
This test method is under the jurisdiction of ASTM Committee E21 on Space
Simulation andApplications of Space Technology and is the direct responsibility of
Subcommittee E21.05 on Contamination. Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
Current edition approved April 1, 2020. Published April 2020. Originally 4th Floor, New York, NY 10036, http://www.ansi.org.
approved in 1988. Last previous edition approved in 2012 as E1235 – 12. DOI: Available from Standardization Documents Order Desk, Bldg. 4, Section D,
10.1520/E1235-12R20. 700 Robbins Ave., Philadelphia, PA, 19111-5094, Attn.: NPODS.
2 5
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from Institute of Environmental Sciences, 940 E. Northwest
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Highway, Mount Prospect, IL 60056.
Standards volume information, refer to the standard’s Document Summary page on Available from Committee on Industrial Ventilation, PO Box 16153, Lansing,
the ASTM website. MI 48901.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1235 − 12 (2020)
3.1.1 ISO Class N (airborne particulate cleanliness class), 3.1.11 good housekeeping area, n—anenvironmentallycon-
n—level of airborne particulate concentrations as defined in trolled area without quantitative cleanliness requirements but
N
ISO 14644-1 and 14644-2, where 10 is the maximum maintained in a visibly clean condition.
allowable concentration (particles/m ). 3.1.11.1 Discussion—Office, laboratory, and storage areas
3.1.1.1 Discussion—The considered particle sizes (lower with air conditioning and janitorial service are typical of good
housekeeping areas.
threshold values) applicable for classification with ISO
14644-1 are limited to the range from 0.1 through 5 µm.
3.1.12 HEPA (high effıciency particulate air) filter, n—a
Particleslargerthan5µm(macroparticles)maybeexpressedin
filter for air with a removal efficiency in excess of 99.97 % for
accordance with Annex E of ISO 14644-1.
0.3-µm particles.
3.1.12.1 Discussion—For this application, HEPA filters
3.1.2 FS209 class, n—the level of cleanliness specified by
shall meet the requirements of IEST-RP-CC001.3, IEST-RP-
the maximum allowable number of particles/ft of air as
CC007.1, IEST-RP-CC034.1, and 6.4 of this test method.
defined in FED-STD-209E.
3.1.2.1 Discussion—This is provided for information and to
3.1.13 molecular contaminant— nonparticulate
facilitate the transition to the use of the ISO classification
contaminant, n—nonparticulate matter.
standard (ISO 14644-1).
3.1.13.1 Discussion—The molecular contaminant may be in
a gaseous, liquid, or solid state. It may be uniformly or
3.1.3 bumping, n—uneven boiling of a liquid caused by
nonuniformly distributed or be in the form of droplets. Mo-
irregular rapid escape of large bubbles of highly volatile
lecular contaminants account for most of the NVR.
components as the liquid mixture is heated or exposed to
vacuum.
3.1.14 NVR (nonvolatile residue), n—quantity of residual
soluble, suspended, and particulate matter remaining after the
3.1.4 clean area, n—a general term that includes
controlled evaporation of a volatile liquid at a specified
cleanrooms, controlled areas, good housekeeping areas, and
temperature.
other areas that have contamination control by physical design
3.1.14.1 Discussion—Theliquidisusuallyfilteredthrougha
and specified operating procedures.
membrane filter, of a specified size, before evaporation to
3.1.5 clean zone, n—a defined space in which the contami-
control the sizes of particles in the NVR. The process used to
nation is controlled to meet specified cleanliness levels.
determine the NVR may affect the quantitative measurement.
3.1.5.1 Discussion—The clean zone may be open or en-
Process factors include filter size, solvent, and the evaporation
closed and may or may not be located within a cleanroom.
temperature and atmosphere. For this reason, the process must
3.1.6 contaminant, n—unwanted molecular and particulate be defined as it is in this test method.
matter that could affect or degrade the performance of the
3.1.15 particle (particulate contaminant), n—a piece of
components upon which they reside.
matter in a solid or liquid (droplet) state with observable
length, width, and thickness.
3.1.7 contamination, n—a process of contaminating.
3.1.16 particle size, n—(1) the apparent maximum linear
3.1.8 controlled area, n—an environmentally controlled
dimensionofaparticleintheplaneofobservation,asobserved
area, operated as a cleanroom, with two prefilter stages but
with an optical microscope; (2) the equivalent diameter of a
without the final stage of HEPA (or better) filters used in
particle detected by automatic instrumentation. The equivalent
cleanrooms.
diameter is the diameter of a reference sphere having known
3.1.8.1 Discussion—Only rough filters (50 to 60 % effi-
properties and producing the same response in the sensing
ciency) and medium efficiency filters (80 to 85 % efficiency)
instrument as the particle being measured; (3) the diameter of
are required for a controlled area. The maximum allowable
acirclehavingthesameareaastheprojectedareaofaparticle,
airborne particle concentrations are ISO Class 8.5 (FS209
in the plane of observation, observed by image analysis; and
Class 283 000) area for particles 0.5 µm and ISO Class 8
(4) the size defined by the measurement technique and calibra-
(FS209 Class 100 000) for particles 5.0 µm.
tion procedure.
3.1.9 environmentally controlled areas, n—a general term
3.1.16.1 Discussion—Because the particle size is defined by
that includes cleanrooms, controlled areas, good housekeeping
the measurement method, the measurement method and size
areas, and other enclosures that are designed to provide an
definition should be stated when specifying or describing
environment suitable for people or products.
particle size.
3.1.9.1 Discussion—The environmental components that
3.1.17 azeotropic mixture, n—a solution of two or more
are controlled include, but are not be limited to, air purity,
liquids, the composition of which does not change upon
temperature, humidity, materials, garments, and personnel
distillation. Also known as azeotrope.
activities.
3.1.10 facility (clean facility), n—the total real property
4. Summary of Test Method
required to accomplish the cleanroom functions.
4.1 Astainless steel plate is exposed within an environmen-
3.1.10.1 Discussion—In addition to the cleanroom and as-
tally controlled area for a known time. It is handled and
sociated clean areas, this includes utility rooms, storage areas,
transported in accordance with Practice E1234.
offices, lockers, washrooms, and other areas that do not
necessarily require precise environmental control. 4.2 The plate is rinsed with a high purity solvent.
E1235 − 12 (2020)
4.3 The solvent is filtered into a beaker, transferred to a 6.5 Vacuum Filtration System, consisting of a 47-mm-
preweighed container, and evaporated at or near room diameter membrane filter funnel and vacuum pump that will
temperature, with a final drying at 35 °C for 30 min. Alterna- provide a pressure of 30 kPa (250 torr) (a vacuum of 20 in.
tive evaporation methods are included. Hg). See Fig. 1.
4.4 The NVR sample is weighed after it has equilibrated to 6.6 Solvent-Resistant Filter, 47-mm diameter, 0.2-µm pore
room temperature and humidity conditions. size (nominal) fluorocarbon.
4.5 AblankstainlesssteelNVRplateisconcurrentlytreated 6.7 Tweezers or Hemostat, stainless steel or coated with
identically to each group of samples to determine solvent TFE-fluorocarbon.
background and handling effects.
6.8 Beakers, low-form, glass, 250 mL, etched with an
4.6 A reagent blank for each group of samples is deter- identification number.
mined.
6.9 Evaporating Dish (Petri Dish), borosilicate glass, ap-
4.7 Each NVR sample, 0.5 mg or greater, is retained for proximately 15 g in mass, 60-mm diameter by 12 mm deep,
organic analysis by infrared spectrometry, or other techniques, and etched with an identification number.
to identify contaminants.
6.10 Liquid Laboratory Detergent.
6.11 Gloves, solvent compatible and resistant.
5. Significance and Use
(Warning—Gloves shall be used to protect the hands from
5.1 The NVR determined by this test method is that amount
accidental spills of the NVR solvent and minimize contamina-
that can reasonably be expected to exist on hardware exposed
tion of exposed samples. Gloves shall be selected to meet local
in environmentally controlled areas.
safety and contamination control requirements.)
5.2 The evaporation of the solvent at or near room tempera-
6.12 NVR Plate, Type 316 corrosion-resistant steel with an
ture is to quantify the NVR that exists at room temperature.
2 2
area of approximately 0.1 m (1 ft ). The plate shown in Fig. 2
5.3 Numerous other methods are being used to determine
has been found to be satisfactory. The finish of the sampling
NVR.Thistestmethodisnotintendedtoreplacemethodsused
surface shall be 0.80 µm (32 µin.) or better per ANSI/ASME
for other applications.
B46.1.The plate shall be electropolished and engraved with an
identification number.
6. Apparatus and Materials
6.13 NVR Plate Cover, Type 316 corrosion-resistant steel.
6.1 Analytical Microbalance, semimicro 5 place, with 30 g
The cover shown in Fig. 3 has been found to be satisfactory.
or greater tare, no greater than 0.01-mg readability, and
Thefinishshallbe0.80µm(32µin.)orbetterperANSI/ASME
60.01-mg precision.
B46.1.Thecovershallbeelectropolishedandengravedwithan
identification number.
6.2 HEPAFiltered,ISOClass5(FS209Class100),orbetter
environment,asdefinedinISO14644-1,unidirectionalairflow,
clean workstation.
6.3 HEPAFiltered,ISOClass5(FS209Class100),orbetter
Gelman filter funnel P/N 4012/Fisher filtrator assembly Cat. No. 09-788 and
environment, as defined in ISO 14644-1, unidirectional air
Millipore Cat. No. XX1504700 filtration assembly have been found to be satisfac-
flow,exhaustingworkstation,with100 %exhaustforhandling
tory. Other suitable filtration apparatus may be used.
solvents.
Millipore Corp. Fluoropore filter Cat. No. FGLP04700, and Gelman Sciences,
Inc. Prod. 66143 PTFE have been found to be satisfactory. Other equivalent solvent
NOTE 1—The exhausting work station is recommended to prevent
resistant filters may be used.
solvent vapors from entering the laboratory area (see Industrial
Pioneer green nitrile gloves, Catalog No. A10-1, have been found to be
Ventilation, a Manual of Recommended Practice).
satisfactory.
NOTE 2—Verify that the airborne particle concentrations in the work
stations are ISO Class 5 FS209 Class 100, or better, per ISO 14644-1,
when tested in accordance with Practice F50.
NOTE 3—Verify NVR levels in the work stations are acceptable using
the procedures in this standard.
6.4 HEPA Filters—All HEPA filters shall be constructed of
low outgassing, corrosion-resistant, and fire-resistant materials
such as Grade 1 in IEST-RP-CC001.3. Filters with stainless
steel or aluminum frames should be considered. The filters
shall not be tested with DOP (dioctylphthalate) or other liquid
aerosols. Ambient air and solid aerosol test methods are
acceptable alternatives to the DOP test. Applicable test meth-
ods from IEST-RP-CC007.1 and IEST-RP-CC034.1 shall be
considered.
Sartorius Model R180D, or equivalent. FIG. 1 Vacuum Filtration Apparatus
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E1235 − 12 E1235 − 12 (Reapproved 2020)
Standard Test Method for
Gravimetric Determination of Nonvolatile Residue (NVR) in
Environmentally Controlled Areas for Spacecraft
This standard is issued under the fixed designation E1235; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the determination of nonvolatile residue (NVR) fallout in environmentally controlled areas used for
the assembly, testing, and processing of spacecraft.
1.2 The NVR of interest is that which is deposited on sampling plate surfaces at room temperature: it is left to the user to infer
the relationship between the NVR found on the sampling plate surface and that found on any other surfaces.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
E1234 Practice for Handling, Transporting, and Installing Nonvolatile Residue (NVR) Sample Plates Used in Environmentally
Controlled Areas for Spacecraft
F50 Practice for Continuous Sizing and Counting of Airborne Particles in Dust-Controlled Areas and Clean Rooms Using
Instruments Capable of Detecting Single Sub-Micrometre and Larger Particles
2.2 ISO Standards:
14644-1 Cleanrooms and Associated Controlled Environments—Part 1: Classification of Air Cleanliness
14644-2 Cleanrooms and Associated Controlled Environments—Part 2: Specifications for Testing and Monitoring to Prove
Continued Compliance with ISO 14644-1
14951-3 Space Systems—Fluid Characteristics—Part 3: Nitrogen
2.3 U.S. Federal Standard:
FED-STD-209E Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones
2.4 Institute of Environmental Sciences and Technology:
IEST-RP-CC001.3 HEPA and ULPA Filters
IEST-RP-CC007.1 Testing ULPA Filters
IEST-RP-CC034.1 HEPA and ULPA Filter Leak Tests
IEST-STD-CC1246 Product Cleanliness Levels and Contamination Control Program
2.5 American National Standards Institute:
ANSI/ASME B46.1-2009 Surface Texture (Surface Roughness, Waviness, and Lay)
This test method is under the jurisdiction of ASTM Committee E21 on Space Simulation and Applications of Space Technology and is the direct responsibility of
Subcommittee E21.05 on Contamination.
Current edition approved Nov. 1, 2012April 1, 2020. Published November 2012April 2020. Originally approved in 1988. Last previous edition approved in 20082012 as
E1235 – 08.E1235 – 12. DOI: 10.1520/E1235-12.10.1520/E1235-12R20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from Standardization Documents Order Desk, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA, 19111-5094, Attn.: NPODS.
Available from Institute of Environmental Sciences, 940 E. Northwest Highway, Mount Prospect, IL 60056.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1235 − 12 (2020)
2.6 Other:
Industrial Ventilation, A Manual of Recommended Practice, Latest Edition
SMC-TR-95-28, Nonvolatile Residue Solvent Replacement, U.S. Air Force Space and Missile Systems Center, 1 March 1995
3. Terminology
3.1 Definitions:
3.1.1 ISO Class N (airborne particulate cleanliness class), n—level of airborne particulate concentrations as defined in ISO
N 3
14644-1 and 14644-2, where 10 is the maximum allowable concentration (particles/m ).
3.1.1.1 Discussion—
The considered particle sizes (lower threshold values) applicable for classification with ISO 14644-1 are limited to the range from
0.1 through 5 μm. 5 μm. Particles larger than 5 μm (macroparticles) may be expressed in accordance with Annex E of ISO 14644-1.
3.1.2 FS209 class, n—the level of cleanliness specified by the maximum allowable number of particles/ft of air as defined in
FED-STD-209E.
3.1.2.1 Discussion—
This is provided for information and to facilitate the transition to the use of the ISO classification standard (ISO 14644-1).
3.1.3 bumping, n—uneven boiling of a liquid caused by irregular rapid escape of large bubbles of highly volatile components
as the liquid mixture is heated or exposed to vacuum.
3.1.4 clean area, n—a general term that includes cleanrooms, controlled areas, good housekeeping areas, and other areas that
have contamination control by physical design and specified operating procedures.
3.1.5 clean zone, n—a defined space in which the contamination is controlled to meet specified cleanliness levels.
3.1.5.1 Discussion—
The clean zone may be open or enclosed and may or may not be located within a cleanroom.
3.1.6 contaminant, n—unwanted molecular and particulate matter that could affect or degrade the performance of the
components upon which they reside.
3.1.7 contamination, n—a process of contaminating.
3.1.8 controlled area, n—an environmentally controlled area, operated as a cleanroom, with two prefilter stages but without the
final stage of HEPA (or better) filters used in cleanrooms.
3.1.8.1 Discussion—
Only rough filters (50 to 60 % efficiency) and medium efficiency filters (80 to 85 % efficiency) are required for a controlled area.
The maximum allowable airborne particle concentrations are ISO Class 8.5 (FS209 Class 283 000) area for particles 0.5 μm and
ISO Class 8 (FS209 Class 100 000) for particles 5.0 μm.
3.1.9 environmentally controlled areas, n—a general term that includes cleanrooms, controlled areas, good housekeeping areas,
and other enclosures that are designed to provide an environment suitable for people or products.
3.1.9.1 Discussion—
The environmental components that are controlled include, but are not be limited to, air purity, temperature, humidity, materials,
garments, and personnel activities.
3.1.10 facility (clean facility), n—the total real property required to accomplish the cleanroom functions.
3.1.10.1 Discussion—
In addition to the cleanroom and associated clean areas, this includes utility rooms, storage areas, offices, lockers, washrooms, and
other areas that do not necessarily require precise environmental control.
Available from Committee on Industrial Ventilation, PO Box 16153, Lansing, MI 48901.
E1235 − 12 (2020)
3.1.11 good housekeeping area, n—an environmentally controlled area without quantitative cleanliness requirements but
maintained in a visibly clean condition.
3.1.11.1 Discussion—
Office, laboratory, and storage areas with air conditioning and janitorial service are typical of good housekeeping areas.
3.1.12 HEPA (high effıciency particulate air) filter, n—a filter for air with a removal efficiency in excess of 99.97 % for 0.3-μm
particles.
3.1.12.1 Discussion—
For this application, HEPA filters shall meet the requirements of IEST-RP-CC001.3, IEST-RP-CC007.1, IEST-RP-CC034.1, and
6.4 of this test method.
3.1.13 molecular contaminant— nonparticulate contaminant, n—nonparticulate matter.
3.1.13.1 Discussion—
The molecular contaminant may be in a gaseous, liquid, or solid state. It may be uniformly or nonuniformly distributed or be in
the form of droplets. Molecular contaminants account for most of the NVR.
3.1.14 NVR (nonvolatile residue), n—quantity of residual soluble, suspended, and particulate matter remaining after the
controlled evaporation of a volatile liquid at a specified temperature.
3.1.14.1 Discussion—
The liquid is usually filtered through a membrane filter, of a specified size, before evaporation to control the sizes of particles in
the NVR. The process used to determine the NVR may affect the quantitative measurement. Process factors include filter size,
solvent, and the evaporation temperature and atmosphere. For this reason, the process must be defined as it is in this test method.
3.1.15 particle (particulate contaminant), n—a piece of matter in a solid or liquid (droplet) state with observable length, width,
and thickness.
3.1.16 particle size, n—(1) the apparent maximum linear dimension of a particle in the plane of observation, as observed with
an optical microscope; (2) the equivalent diameter of a particle detected by automatic instrumentation. The equivalent diameter
is the diameter of a reference sphere having known properties and producing the same response in the sensing instrument as the
particle being measured; (3) the diameter of a circle having the same area as the projected area of a particle, in the plane of
observation, observed by image analysis; and (4) the size defined by the measurement technique and calibration procedure.
3.1.16.1 Discussion—
Because the particle size is defined by the measurement method, the measurement method and size definition should be stated when
specifying or describing particle size.
3.1.17 azeotropic mixture, n—a solution of two or more liquids, the composition of which does not change upon distillation.
Also known as azeotrope.
4. Summary of Test Method
4.1 A stainless steel plate is exposed within an environmentally controlled area for a known time. It is handled and transported
in accordance with Practice E1234.
4.2 The plate is rinsed with a high purity solvent.
4.3 The solvent is filtered into a beaker, transferred to a preweighed container, and evaporated at or near room temperature, with
a final drying at 35°C35 °C for 30 min. Alternative evaporation methods are included.
4.4 The NVR sample is weighed after it has equilibrated to room temperature and humidity conditions.
4.5 A blank stainless steel NVR plate is concurrently treated identically to each group of samples to determine solvent
background and handling effects.
4.6 A reagent blank for each group of samples is determined.
4.7 Each NVR sample, 0.5 mg or greater, is retained for organic analysis by infrared spectrometry, or other techniques, to
identify contaminants.
E1235 − 12 (2020)
5. Significance and Use
5.1 The NVR determined by this test method is that amount that can reasonably be expected to exist on hardware exposed in
environmentally controlled areas.
5.2 The evaporation of the solvent at or near room temperature is to quantify the NVR that exists at room temperature.
5.3 Numerous other methods are being used to determine NVR. This test method is not intended to replace methods used for
other applications.
6. Apparatus and Materials
6.1 Analytical Microbalance, semimicro 5 place, with 30 g or greater tare, no greater than 0.01-mg readability, and 60.01-mg
precision.
6.2 HEPA Filtered, ISO Class 5 (FS209 Class 100), or better environment, as defined in ISO 14644-1, unidirectional airflow,
clean workstation.
6.3 HEPA Filtered, ISO Class 5 (FS209 Class 100), or better environment, as defined in ISO 14644-1, unidirectional air flow,
exhausting work station, with 100 % exhaust for handling solvents.
NOTE 1—The exhausting work station is recommended to prevent solvent vapors from entering the laboratory area (see Industrial Ventilation, a Manual
of Recommended Practice).
NOTE 2—Verify that the airborne particle concentrations in the work stations are ISO Class 5 FS209 Class 100, or better, per ISO 14644-1, when tested
in accordance with Practice F50.
NOTE 3—Verify NVR levels in the work stations are acceptable using the procedures in this standard.
6.4 HEPA Filters—All HEPA filters shall be constructed of low outgassing, corrosion-resistant, and fire-resistant materials such
as Grade 1 in IEST-RP-CC001.3. Filters with stainless steel or aluminum frames should be considered. The filters shall not be
tested with DOP (dioctylphthalate) or other liquid aerosols. Ambient air and solid aerosol test methods are acceptable alternatives
to the DOP test. Applicable test methods from IEST-RP-CC007.1 and IEST-RP-CC034.1 shall be considered.
6.5 Vacuum Filtration System, consisting of a 47-mm-diameter membrane filter funnel and vacuum pump that will provide a
pressure of 30 kPa (250 torr) (a vacuum of 20 in. Hg). See Fig. 1.
6.6 Solvent-Resistant Filter, 47-mm diameter, 0.2-μm pore size (nominal) fluorocarbon.
6.7 Tweezers or Hemostat, stainless steel or coated with TFE-fluorocarbon.
6.8 Beakers, low-form, glass, 250 mL, etched with an identification number.
6.9 Evaporating Dish (Petri Dish), borosilicate glass, approximately 15 g in mass, 60-mm diameter by 12 mm deep, and etched
with an identification number.
6.10 Liquid Laboratory Detergent.
FIG. 1 Vacuum Filtration Apparatus
Sartorius Model R180D, or equivalent.
Gelman filter funnel P/N 4012/Fisher filtrator assembly Cat. No. 09-788 and Millipore Cat. No. XX1504700 filtration assembly have been found to be satisfactory. Other
suitable filtration apparatus may be used.
Millipore Corp. Fluoropore filter Cat. No. FGLP 04700, and Gelman Sciences, Inc. Prod. 66143 PTFE have been found to be satisfactory. Other equivalent solvent
resistant filters may be used.
E1235 − 12 (2020)
6.11 Gloves, solvent compatible and resistant. (Warning—Gloves shall be used to protect the hands from accidental spills of
the NVR solvent and minimize contamination of exposed samples. Gloves shall be selected to meet local safety and contamination
control requirements.)
2 2
6.12 NVR Plate, Type 316 corrosion-resistant steel with an area of approximately 0.1 m (1 ft ). The plate shown in Fig. 2 h
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