ASTM D2784 Test Method for Sulfur in Liquefied Petroleum Gases (Oxy-Hydrogen Burner or Lamp)
16. Calculation
16.1 Calculate the amount of sulfur in the sample as follows:
Sulfur content, µg/g = A/W
where:
A = micrograms of sulfur as obtained in 11.6 or 15.5, and
W = grams of sample burned.

16.1.1 Round the result of the test to the nearest 1 µg/g of sulfur.

16.2 Alternatively calculate the concentration in units of grains of total sulfur per 100 ft3 as follows:
R (for propane) = 0.083S
R (for butane) = 0.111S
R (for propane - butane mixtures) = S [0.366 (G - 0.5077) + 0.083]
where:
R = grains of total sulfur per 100 ft3 of gas at 15.6°C (60°F) and 0.10132 MPa (760 mm) Hg,
S = sulfur content, µg/g, and
G = relative density of the mixture at 15.6/15.6°C (60/60°F).

NOTE 14 - The derivatives of constants used in the above equations are based on the following properties of propane and butane:
Specific volume for propane (of the real gas at 60°F and 14.696 psig), ft 3 /lb of gas: 8.4515
Specific volume for butane (same conditions as above): 6.3120

NOTE 15 - If the relative density of the mixture is not known, determine it by Test Method D1657.

NOTE 16 - Multiply by 2.2883 to convert grains per cubic foot to grams per cubic metre. Multiply by 35.31 to convert grains per cubic metres to grams per cubic feet.

17. Quality Control
17.1 Confirm the performance of the apparatus or the procedure, or both, each day it is in use by analyzing a QC sample (6.7) that is representative of samples typically analyzed. Analysis of the result(s) from the QC sample(s) can be carried out using control charts, or other statistically equivalent techniques, to ascertain the control status of the total testing process. Any out of control data should trigger investigation for root cause.

18. Precision and Bias
18.1 The precision of this test method has not been determined. The responsible subcommittee is attempting to attract volunteers for an interlaboratory study.

18.2 The bias of this test method cannot be determined since appropriate reference material containing a known level of sulfur in liquefied petroleum gases is not available.

19. Keywords
19.1 lamp; liquefied petroleum gas; oxy-hydrogen burner; sulfur