ASTM D4051-10(2015)
(Practice)Standard Practice for Preparation of Low-Pressure Gas Blends
Standard Practice for Preparation of Low-Pressure Gas Blends
SIGNIFICANCE AND USE
3.1 The laboratory preparation of gas blends of known composition is required to provide primary standards for the calibration of chromatographic and other types of analytical instrumentation.
SCOPE
1.1 This practice covers a laboratory procedure for the preparation of low-pressure multicomponent gas blends. The technique is applicable to the blending of components at percent levels and can be extended to lower concentrations by performing dilutions of a previously prepared base blend. The maximum blend pressure obtainable is dependent upon the range of the manometer used, but ordinarily is about 101 kPa (760 mm Hg). Components must not be condensable at the maximum blend pressure.
1.2 The possible presence of small leaks in the manifold blending system will preclude applicability of the method to blends containing part per million concentrations of oxygen or nitrogen.
1.3 This practice is restricted to those compounds that do not react with each other, the manifold, or the blend cylinder.
1.4 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D4051 − 10 (Reapproved 2015)
Standard Practice for
Preparation of Low-Pressure Gas Blends
This standard is issued under the fixed designation D4051; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Significance and Use
3.1 The laboratory preparation of gas blends of known
1.1 This practice covers a laboratory procedure for the
composition is required to provide primary standards for the
preparation of low-pressure multicomponent gas blends. The
calibration of chromatographic and other types of analytical
technique is applicable to the blending of components at
instrumentation.
percent levels and can be extended to lower concentrations by
performing dilutions of a previously prepared base blend. The
4. Apparatus
maximum blend pressure obtainable is dependent upon the
4.1 Blending Manifold—Construct manifold as shown in
range of the manometer used, but ordinarily is about 101kPa
Fig. 1. Details of construction are not critical; that is, glass,
(760mm Hg). Components must not be condensable at the
pipe, or tubing with welded or compression fittings may be
maximum blend pressure.
used. The manifold must be leak free and arranged for
convenience of operation. More than one feedstock connection
1.2 The possible presence of small leaks in the manifold
point may be included if desired. Connections to the pump and
blending system will preclude applicability of the method to
manometershallfollowacceptedvacuumpractice.Valvesshall
blends containing part per million concentrations of oxygen or
have large enough apertures to permit adequate pumping in a
nitrogen.
reasonable length of time.
1.3 This practice is restricted to those compounds that do
4.1.1 Thefinishedmanifoldshallhavealeakratenogreater
not react with each other, the manifold, or the blend cylinder.
than 1mm Hg/h (0.133kPa⁄h).
1.4 This standard does not purport to address all of the 4.2 Gauge, a well-type manometer such as the Meriam
safety concerns, if any, associated with its use. It is the Model 30EB25 (see Note 1).
responsibility of the user of this standard to establish appro-
NOTE 1—Ahigh-vacuum gauge of the McLeod Manostat type pressure
priate safety and health practices and determine the applica-
transducer or a 0bar to 2bar (absolute) gauge may be included in the
manifold system to determine how well the system has been evacuated.
bility of regulatory limitations prior to use.
4.2.1 Alternatively, an electronic pressure gauge may be
2. Summary of Practice
used in place of a manometer.
4.3 Pump, high-vacuum, two-stage, capable of pumping
2.1 Through the use of a blending manifold, the blend
–4
down to a pressure of 1.33×10 kPa (0.1µm).
components are combined based upon partial pressure. Com-
ponentsareaddedinorderofascendingvaporpressure;thatis,
5. Reagents and Materials
components of lowest vapor pressure are added first, with the
5.1 Blend Components, high-purity, as required depending
exception that components at concentrations of 5% or less
on the composition of the proposed blend.
would usually be added first. Compressibility factors are
applied to the component partial pressures to convert them
5.2 Nitrogen, high purity, as required, for purging and for
from ideal to real gas. The real partial pressures, which are
balance gas, where applicable.
proportional to gas volumes, are normalized to give mol
6. Procedure
percent composition of the blend.
6.1 ConnecttheblendcylindertothemanifoldatpositionA
(seeFig.1forvalveandpositiondesignations).Openvalves1,
1 2, 3, and 6 and evacuate the manifold system thoroughly.
This practice is under the jurisdiction ofASTM Committee D02 on Petroleum
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
Valves 4 and 5 are closed.
mittee D02.04.0A on Preparation of Standard Hydrocarbon Blends.
NOTE2—AMcLeodManostattypegaugemaybeusedatvarioustimes
Current edition approved Oct. 1, 2015. Published December 2015. Originally
approved in 1981. Last previous edition approved in 2010 as D4051–10. DOI: during the procedure to determine how well the system has been
10.1520/D4051-10R15. evacuated and to indicate if there are leaks present. Otherwise, a steady
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4051 − 10 (2015)
FIG. 1 Manifold System
state condition of the manometer or electronic pressure gauge reading can NOTE 3—All additions should be made slowly to avoid temperature
be taken as an indication that an acceptable vacuum has been attained. changes.
6.1.1 When a good vacuum less than 0.01kPa (0.1mm Hg)
6.1.5 When the pressure in the manifold is several pascals
is reached, connect one or more blend component cylinders to
higher than the previous reading and is still slowly rising,
the manifold at positions B or C, or both. Close valve 2 and
slowly begin to open valve 3 so as to admit the component to
open valves 4 and 5, thereby evacuating the connecting lines
the sample cylinder. Valve 4 will remain partially open.
up to the blend component cylinder valves. When a good
Continue to open valve 3 while controlling the flow through
vacuum is again reached, close valves 4 and 5 and open the
valve 4 until the next desired pressure level is reached, always
blend component cylinder valves. Ensure that the pressure of
maintaining a higher pressure in the manifold than that in the
any blend component delivered to valves 4 and 5 does not
cylinder. Close valve 4, allow the pressure to equilibrate, and
exceed 200kPa (1500mm Hg). Record the initial pressure
record the manometer reading from both sides. Close valve 3.
readings from both sides of the manometer. When additional components are to be included in the blend,
6.1.2 The first component to be added will either have the
repeat the procedures outlined above for each component.
lowest vapor pressure or will be present in the final blend at a
6.1.6 When all components have been added, and valve3 is
concentration of 5% or less. Assume that the first component
closed,evacuatethemanifold,closevalve2anddisconnectthe
feedstock is connected to manifold valve 4. Close valve 1 and
blend cylinder from the manifold at position A. To shut down
open valve 2. While carefully watching the manometer or
the apparatus, close the feedstock cylinder valve and open
electronic pressure gauge reading, slowly open valve 4.Allow
valve 4 to evacuate the connection. Close valve 4, remove the
the blend gas component to flow into the blend manifold until
feedstock cylinder, close valve 1, and by using valve 2 or 4,
the desired precalculated manometer reading is reached (see
slowly admit air into the system until it is at atmospheric
7.1). Close valve 4 and be sure that the pressure remains
pressure.
constant. If using a manometer, tap it lightly to be certain the
6.2 The blend must be mixed before it is used. This can be
correctreadingisobtained.Recordthereadingofbothsidesof
accomplished in several ways, one of which is to cause
the manometer and then close valve 3. Open valve 1 and wait
convection currents to occur within the cylinder. This may
until the manifold is thoroughly evacuated.
conveniently be done by heating one end of the cylinder with
6.1.3 If the manifold includes only one feedstock connec-
either a hot air gun or by running hot water over one end of it
tion point it will be necessary at this time to remove the first
for about an hour. Never use a flame to heat the cylinder.
feedstock cylinder, connect the second, and evacuate the line
Blendscontaininghydrogenorheliumareverydifficulttomix.
back to the feedstock cylinder valve. Assume this to be the
Therefore, it is necessary to periodically alternate heating of
case; value 4 will, therefore, always be used as the feedstock
first one end of the cylinder and then the other for several
control valve.
hours.
6.1.4 When manifold evacuation is complete, cl
...
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: D4051 − 10 D4051 − 10 (Reapproved 2015)
Standard Practice for
Preparation of Low-Pressure Gas Blends
This standard is issued under the fixed designation D4051; 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*Scope
1.1 This practice covers a laboratory procedure for the preparation of low-pressure multicomponent gas blends. The technique
is applicable to the blending of components at percent levels and can be extended to lower concentrations by performing dilutions
of a previously prepared base blend. The maximum blend pressure obtainable is dependent upon the range of the manometer used,
but ordinarily is about 101 kPa (760 mm 101 kPa (760 mm Hg). Components must not be condensable at the maximum blend
pressure.
1.2 The possible presence of small leaks in the manifold blending system will preclude applicability of the method to blends
containing part per million concentrations of oxygen or nitrogen.
1.3 This practice is restricted to those compounds that do not react with each other, the manifold, or the blend cylinder.
1.4 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Summary of Practice
2.1 Through the use of a blending manifold, the blend components are combined based upon partial pressure. Components are
added in order of ascending vapor pressure; that is, components of lowest vapor pressure are added first, with the exception that
components at concentrations of 5 % or less would usually be added first. Compressibility factors are applied to the component
partial pressures to convert them from ideal to real gas. The real partial pressures, which are proportional to gas volumes, are
normalized to give mol percent composition of the blend.
3. Significance and Use
3.1 The laboratory preparation of gas blends of known composition is required to provide primary standards for the calibration
of chromatographic and other types of analytical instrumentation.
4. Apparatus
4.1 Blending Manifold—Construct manifold as shown in Fig. 1. Details of construction are not critical; that is, glass, pipe, or
tubing with welded or compression fittings may be used. The manifold must be leak free and arranged for convenience of
operation. More than one feedstock connection point may be included if desired. Connections to the pump and manometer shall
follow accepted vacuum practice. Valves shall have large enough apertures to permit adequate pumping in a reasonable length of
time.
4.1.1 The finished manifold shall have a leak rate no greater than 1 mm 1 mm Hg/h (0.133 (0.133 kPa kPa/h).⁄h).
4.2 Gauge, a well-type manometer such as the Meriam Model 30EB25 (see Note 1).
NOTE 1—A high-vacuum gauge of the McLeod Manostat type pressure transducer or a 00 bar to 2 bar 2 bar (absolute) gauge may be included in the
manifold system to determine how well the system has been evacuated.
4.2.1 Alternatively, an electronic pressure gauge may be used in place of a manometer.
–4
4.3 Pump, high-vacuum, two-stage, capable of pumping down to a pressure of 1.33 × 10 kPa (0.1 μm). kPa (0.1 μm).
This practice is under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.04.0A on Preparation of Standard Hydrocarbon Blends.
Current edition approved May 1, 2010Oct. 1, 2015. Published July 2010December 2015. Originally approved in 1981. Last previous edition approved in 20042010 as
D4051–99(2004).D4051 – 10. DOI: 10.1520/D4051-10.10.1520/D4051-10R15.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4051 − 10 (2015)
FIG. 1 Manifold System
5. Reagents and Materials
5.1 Blend Components, high-purity, as required depending on the composition of the proposed blend.
5.2 Nitrogen, high purity, as required, for purging and for balance gas, where applicable.
6. Procedure
6.1 Connect the blend cylinder to the manifold at position A (see Fig. 1 for valve and position designations). Open valves 1,2,3,
and 6 and evacuate the manifold system thoroughly. Valves 4 and 5 are closed.
NOTE 2—A McLeod Manostat type gauge may be used at various times during the procedure to determine how well the system has been evacuated
and to indicate if there are leaks present. Otherwise, a steady state condition of the manometer or electronic pressure gauge reading can be taken as an
indication that an acceptable vacuum has been attained.
6.1.1 When a good vacuum less than 0.01 kPa (0.1 mm 0.01 kPa (0.1 mm Hg) is reached, connect one or more blend component
cylinders to the manifold at positions B or C, or both. Close valve 2 and open valves 4 and 5, thereby evacuating the connecting
lines up to the blend component cylinder valves. When a good vacuum is again reached, close valves 4 and 5 and open the blend
component cylinder valves. Ensure that the pressure of any blend component delivered to valves 4 and 5 does not exceed 200 kPa
(1500 mm 200 kPa (1500 mm Hg). Record the initial pressure readings from both sides of the manometer.
6.1.2 The first component to be added will either have the lowest vapor pressure or will be present in the final blend at a
concentration of 5 % or less. Assume that the first component feedstock is connected to manifold valve 4. Close valve 1 and open
valve 22. . While carefully watching the manometer or electronic pressure gauge reading, slowly open valve 4. Allow the blend
gas component to flow into the blend manifold until the desired precalculated manometer reading is reached (see 7.1). Close valve
4 and be sure that the pressure remains constant. If using a manometer, tap it lightly to be certain the correct reading is obtained.
Record the reading of both sides of the manometer and then close valve 3. Open valve 1 and wait until the manifold is thoroughly
evacuated.
6.1.3 If the manifold includes only one feedstock connection point it will be necessary at this time to remove the first feedstock
cylinder, connect the second, and evacuate the line back to the feedstock cylinder valve. Assume this to be the case; value 4 will,
therefore, always be used as the feedstock control valve.
6.1.4 When manifold evacuation is complete, close valve 1 and 4. Open the feedstock cylinder valve and then slowly open valve
4, allowing the second blend gas to flow into the manifold. Carefully watch the manometer or electronic pressure gauge.
NOTE 3—All additions should be made slowly to avoid temperature changes.
6.1.5 When the pressure in the manifold is several pascals higher than the previous reading and is still slowly rising, slowly
begin to open valve 3 so as to admit the component to the sample cylinder. Valve 4 will remain partially open. Continue to open
valve 3 while controlling the flow through valve 4 until the next desired pressure level is reached, always maintaining a higher
pressure in the manifold than that in the cylinder. Close valve 4, allow the pressure to equilibrate, and record the manometer
reading from both sides. Close valve 3. When additional components are to be included in the blend, repeat the procedures outlined
above for each component.
D4051 − 10 (2015)
6.1.6 When all components have been added, and valve 3 is closed, evacuate the manifold, close valve 2 and disconnect the
blend cylinder from the manifold at position A. To shut down the apparatus, close the feedstock cylinder valve and open valve 4
to evacuate the connection. Close valve 4, remove the feedstock cylinder, close valve 1, and by using valve 2 or 4,slowly admit
air into the system until it is at atmospheric pressure.
6.2 The blend must be mixed before it is used. This can be accomplished in several ways, one of which is to cause convection
currents to occur within the cylinder. This may conveniently be done by heating one end of the cylinder with either a hot air gun
or by running hot water over one end of it for about an hour. Never use a flame to heat the cylinder. Blends
...
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