ASTM D4051-10(2021)
(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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
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.
General Information
Standards Content (Sample)
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.
Designation: D4051 − 10 (Reapproved 2021)
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 from ideal to real gas. The real partial pressures, which are
proportional to gas volumes, are normalized to give mol
1.1 This practice covers a laboratory procedure for the
percent composition of the blend.
preparation of low-pressure multicomponent gas blends. The
technique is applicable to the blending of components at
3. Significance and Use
percent levels and can be extended to lower concentrations by
3.1 The laboratory preparation of gas blends of known
performing dilutions of a previously prepared base blend. The
composition is required to provide primary standards for the
maximum blend pressure obtainable is dependent upon the
calibration of chromatographic and other types of analytical
range of the manometer used, but ordinarily is about 101kPa
instrumentation.
(760mm Hg). Components must not be condensable at the
maximum blend pressure.
4. Apparatus
1.2 The possible presence of small leaks in the manifold
4.1 Blending Manifold—Construct manifold as shown in
blending system will preclude applicability of the method to
Fig. 1. Details of construction are not critical; that is, glass,
blends containing part per million concentrations of oxygen or
pipe, or tubing with welded or compression fittings may be
nitrogen.
used. The manifold must be leak free and arranged for
convenience of operation. More than one feedstock connection
1.3 This practice is restricted to those compounds that do
point may be included if desired. Connections to the pump and
not react with each other, the manifold, or the blend cylinder.
manometershallfollowacceptedvacuumpractice.Valvesshall
1.4 This standard does not purport to address all of the
have large enough apertures to permit adequate pumping in a
safety concerns, if any, associated with its use. It is the
reasonable length of time.
responsibility of the user of this standard to establish appro-
4.1.1 Thefinishedmanifoldshallhavealeakratenogreater
priate safety, health, and environmental practices and deter-
than 1mm Hg/h (0.133kPa⁄h).
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor- 4.2 Gauge, a well-type manometer such as the Meriam
dance with internationally recognized principles on standard-
Model 30EB25 (see Note 1).
ization established in the Decision on Principles for the
NOTE 1—Ahigh-vacuum gauge of the McLeod Manostat type pressure
Development of International Standards, Guides and Recom-
transducer or a 0bar to 2bar (absolute) gauge may be included in the
mendations issued by the World Trade Organization Technical
manifold system to determine how well the system has been evacuated.
Barriers to Trade (TBT) Committee.
4.2.1 Alternatively, an electronic pressure gauge may be
used in place of a manometer.
2. Summary of Practice
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
5.2 Nitrogen, high purity, as required, for purging and for
applied to the component partial pressures to convert them
balance gas, where applicable.
6. Procedure
This practice is under the jurisdiction ofASTM Committee D02 on Petroleum
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
6.1 ConnecttheblendcylindertothemanifoldatpositionA
mittee D02.04.0A on Preparation of Standard Hydrocarbon Blends.
(seeFig.1forvalveandpositiondesignations).Openvalves1,
Current edition approved Jan. 1, 2021. Published February 2021. Originally
2, 3, and 6 and evacuate the manifold system thoroughly.
approved in 1981. Last previous edition approved in 2015 as D4051–10 (2015).
DOI: 10.1520/D4051-10R21. Valves 4 and 5 are closed.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4051 − 10 (2021)
FIG. 1 Manifold System
NOTE2—AMcLeodManostattypegaugemaybeusedatvarioustimes
valve 4, allowing the second blend gas to flow into the
during the procedure to determine how well the system has been
manifold. Carefully watch the manometer or electronic pres-
evacuated and to indicate if there are leaks present. Otherwise, a steady
sure gauge.
state condition of the manometer or electronic pressure gauge reading can
be taken as an indication that an acceptable vacuum has been attained.
NOTE 3—All additions should be made slowly to avoid temperature
changes.
6.1.1 When a good vacuum less than 0.01kPa (0.1mm Hg)
is reached, connect one or more blend component cylinders to
6.1.5 When the pressure in the manifold is several pascals
the manifold at positions B or C, or both. Close valve 2 and
higher than the previous reading and is still slowly rising,
open valves 4 and 5, thereby evacuating the connecting lines
slowly begin to open valve 3 so as to admit the component to
up to the blend component cylinder valves. When a good
the sample cylinder. Valve 4 will remain partially open.
vacuum is again reached, close valves 4 and 5 and open the
Continue to open valve 3 while controlling the flow through
blend component cylinder valves. Ensure that the pressure of
valve 4 until the next desired pressure level is reached, always
any blend component delivered to valves 4 and 5 does not
maintaining a higher pressure in the manifold than that in the
exceed 200kPa (1500mm Hg). Record the initial pressure
cylinder. Close valve 4, allow the pressure to equilibrate, and
readings from both sides of the manometer.
record the manometer reading from both sides. Close valve 3.
6.1.2 The first component to be added will either have the
When additional components are to be included in the blend,
lowest vapor pressure or will be present in the final blend at a
repeat the procedures outlined above for each component.
concentration of 5% or less. Assume that the first component
6.1.6 When all components have been added, and valve3 is
feedstock is connected to manifold valve 4. Close valve 1 and
closed,evacuatethemanifold,closevalve2anddisconnectthe
open valve 2. While carefully watching the manometer or
blend cylinder from the manifold at position A. To shut down
electronic pressure gauge reading, slowly open valve 4.Allow
the apparatus, close the feedstock cylinder valve and open
the blend gas component to flow into the blend manifold until
valve 4 to evacuate the connection. Close valve 4, remove the
the desired precalculated manometer reading is reached (see
feedstock cylinder, close valve 1, and by using valve 2 or 4,
7.1). Close valve 4 and be sure that the pressure remains
slowly admit air into the system until it is at atmospheric
constant. If using a manometer, tap it lightly to be certain the
pressure.
correctreadingisobtained.Recordthereadingofbothsidesof
the manometer and then close valve 3. Open valve 1 and wait 6.2 The blend must be mixed before it is used. This can be
until the manifold is thoroughly evacuated. accomplished in several ways, one of which is to cause
6.1.3 If the manifold includes only one feedstock connec- convection currents to occur within the cylinder. This may
tion point it will be necessary at this time to remove the first conveniently be done by heating one end of the cylinder with
feedstock cylinder, connect the second, and evacuate the line either a hot air gun or by running hot water over one end of it
back to the feedstock cylinder valve. Assume this to be t
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