ASTM D4178-82(1999)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
An American National Standard
Designation:D4178–82(Reapproved1999)
Standard Practice for
Calibrating Moisture Analyzers
This standard is issued under the fixed designation D 4178; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Apparatus
1.1 This practice describes a calibration technique based on 4.1 Ice Bath Primary Standard Moisture Apparatus—Fig. 1
the preparation of standards of known water content. This illustrates a typical system.
technique is applicable to the production of standards between 4.2 Wet Test Meter, 1-L divisions.
3 3
20 and 2000 cm /m water. 4.3 Bubble Meter, graduated in cubic centimetres.
1.2 The values stated in acceptable metric units are to be 4.4 Pressure Gage—A Bourdon-type spring gage of test
regarded as the standard. gage quality, 100 to 250 mm in diameter, with a scale range
1.3 This standard does not purport to address all of the from 0 to 400 kPa (0 to 60 psi), maximum intermediate
safety concerns, if any, associated with its use. It is the graduations of 1.5 kPa (0.25 psi).
responsibility of the user of this standard to establish appro- 4.5 Wet Mole Sieve 5A, 60/80 mesh (other mesh sizes may
priate safety and health practices and determine the applica- be used, except powder).
bility of regulatory limitations prior to use.
5. Preparation of Apparatus
2. Summary of Practice
5.1 Saturate mole sieve with water.
2.1 The practice is based on the principle that ice has a 5.1.1 Coverinbeakerenoughmolesievetofillthewetmole
vapor pressure of 0.611 kPa at 0°C. Therefore, when a carrier sieve container. Add water to cover mole sieve. Let stand
gas at a constant gage pressure of 207 kPa (30 psig) is passed overnight.
throughamolecularsievesaturatedwithwaterandheldat0°C, 5.1.2 Drain the excess water by pouring the mole sieve
the total pressure is equal to 207 kPa plus 98 kPa (one slurry into a filtering funnel and letting all the free water drain
atmosphere) and the water concentration of the gas leaving the out.
molecular sieve is [0.611/(207 + 98)] 3 10 ppm or 2000 ppm
NOTE 1—The useful lifetime of the wet mole sieve is not known. It is
volume water, regardless of flow.
recommended that the procedure described in 5.1.1 and 5.1.2 be followed
2.1.1 Acarrier gas at a constant gage pressure of 207 kPa is
prior to each calibration.
passed through a molecular sieve drier and then routed over a
6. Procedure
molecular sieve support saturated with water and equilibrated
at 0°C.
6.1 Fill the ice bath bucket for the primary standard appa-
2.1.2 By blending different volumes of the wet carrier gas
ratus one third full of water; then add ice to bring the level to
with dried carrier gas, gas standards of known water concen-
full.
tration can be prepared.
6.2 Close the wet flow and the diluent flow needle values.
2.2 The moisture analyzer to be calibrated is then connected
6.3 Turn on the carrier gas supply (nitrogen or air) and
to the source of the gas standard of known water concentration.
adjust the regulator to 207 kPa (30 psig).
6.4 Open the diluent flow needle valve to obtain a carrier
3. Significance and Use
gas flow of 1 L/min, as measured with a wet test meter.
3.1 This practice is intended to provide a method to cali-
6.5 Allow the apparatus to equilibrate for 1 h. This allows
brate moisture analyzers used on-stream or in the laboratory.
the wet mole sieve to equilibrate at 0°C.
6.6 After 1 h, attach the moisture analyzer to be calibrated
and check that the blank moisture content of the carrier gas is
This practice is under the jurisdiction of ASTM Committee D02 on Petroleum
6 ppm or less.
ProductsandLubricantsandisthedirectresponsibilityofSubcommitteeD02.D0on
3 3
6.7 Turn off the diluent flow, cm /m .
Hydrocarbons for Chemical and Special Uses.
Cur
...