Liquefied petroleum gases test methods

Bulk physical property tests, such as density and heating value, as well as some compositional tests, such as the Orsat analysis and the mercuric nitrate method for the determination of unsaturation, are still used. However, the choice of a particular test is dictated by (1) the requirements of the legislation, (2) the properties of the gas under study, and (3) the selection by the analyst of a suitable suite of tests to meet the various requirements. For example, judgment by the analyst is necessary whether or not a test that is applied to liquefied petroleum gas is suitable for process gas or natural gas insofar as inference from the nonhydrocarbon constituents will be minimal. 

This test method (ASTM D-2784, IP 243) is valid for sulfur levels of >1 pg/g of sulfur in liquefied petroleum gas, but the samples should not contain more than 100 pg/g of chlorine. In the test, the sample is burned in an oxy-hydrogen burner or in a lamp in a closed system in a carbon dioxide-oxygen atmosphere. The latter is not recommended for trace quantities of sulfur... 

Total sulfur in gas can be determined by combustion (ASTM D-1072), by the lamp method (ASTM D-1266), or by hydrogenation (ASTM D-3031, ASTM D-4468). Trace total organic and bound nitrogen is determined (ASTM D-4629). The current test method for heavy residues in liquefied petroleum gas (ASTM D-2158) involves evaporation of a liquefied petroleum gas sample, measuring the volume of residue and observing the residue for oil stain on a piece of filter paper. 

Corrosive sulfur compounds can be detected by their effect on copper and the form in which the general copper strip corrosion test (ASTM D-1838) for petroleum products is appUed to liquefied petroleum gas. Hydrogen sulfide can be detected by its action on moist lead acetate paper, and a procedure is also used as a measure of sulfur compounds. The method follows the principle of the standard Doctor test. 

It is a fundamental requirement that liquefied petroleum gas should not contain free water (ASTM D-2713). Dissolved water may give trouble by forming hydrates and giving moisture vapor in the gas phase. Both of these will lead to blockages. Therefore, test methods are available to determine the presence of water using electronic moisture analyzers (ASTM D-5454), dew-point temperature (ASTM D-1142), and length-of-stain detector tubes (ASTM D-4888). 

A furnace test is often more convenient than an open pool fire test. Other possible test environments include pit fires and an open air burner system operating with liquefied petroleum gas [31]. Any such test is acceptable provided it meets the requirements of para. 728. Methods to verily the required heat input and methods to prove the thermal environment can be found in the literature [32-34]. 

ASTM addresses the characterization and specification of the Cl to C5 hydrocarbon materials and products through several venues, Committee D03 is responsible for gaseous fuels Committee D02, Subcommittee H is responsible for liquefied petroleum gas Committee D02, Subcommittee D is responsible for hydrocarbons for chemical and special uses, while Committee D02, Subcommittee 4 has resp>onsibility for test methods involving hydrocarbons in genereJ. Committees D19 (Water) and D22 (Sampling and Analysis of Atmospheres) address environmental concerns involving light hydrocarbons. 

The result can be expressed in terms of measured volumes or indices derived from these volumes. In either case, the test method provides an indication of the quantity and nature of materials in the product that are substantially less volatile than the liquefied petroleum gas hydrocarbons. 

This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.D0.03 on C4 Test Methods Liquefied Petroleum Gas. 

Presence of small amounts of some sulfur compounds in certain refined products (gas and liquid) can have a corrosion effect on copper alloy components of users equipment that adversely affects their function. For example, copper corrosion products could cause plugging of metering and pilot valves. Consequently, product specifications may call for the product to pass a copper corrosion test such as ASTM D 1838, Test Method for Copper Strip Corrosion by Liquefied Petroleum (LP) Gases, or ASTM D 130, Test Method for Detection of Copper Corrosion from Petroleum Products by the Copper Strip Tarnish Test, or ASTM D 4048, Test Method for Detection of Copper Corrosion from Lubricating Grease. 

D2163 Test Method for Analysis of Liquefied Petroleum (LP) Gases and Propene Concentrates by Gas Chromatography ... 

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