[Title 40 CFR 60.648]
[Code of Federal Regulations (annual edition) - July 1, 2009 Edition]
[Title 40 - PROTECTION OF ENVIRONMENT]
[Chapter I - ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)]
[Subchapter C - AIR PROGRAMS (CONTINUED)]
[Part 60 - STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES--]
[Subpart Lll - Standards of Performance for Onshore Natural Gas Processing:]
[Sec. 60.648 - Optional procedure for measuring hydrogen sulfide in acid]
[From the U.S. Government Printing Office]


40PROTECTION OF ENVIRONMENT62009-07-012009-07-01false60.648Sec. 60.648PROTECTION OF ENVIRONMENTENVIRONMENTAL PROTECTION AGENCY (CONTINUED)AIR PROGRAMS (CONTINUED)STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES--Standards of Performance for Onshore Natural Gas Processing:
Sec. 60.648  Optional procedure for measuring hydrogen sulfide in acid
gas--Tutwiler Procedure. \1\
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    \1\ Gas Engineers Handbook, Fuel Gas Engineering Practices, The 
Industrial Press, 93 Worth Street, New York, NY, 1966, First Edition, 
Second Printing, page 6/25 (Docket A-80-20-A, Entry II-I-67).
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    (a) When an instantaneous sample is desired and H2S 
concentration is ten grains per 1000 cubic foot or more, a 100 ml 
Tutwiler burette is used. For concentrations less than ten grains, a 500 
ml Tutwiler burette and more dilute solutions are used. In principle, 
this method consists of titrating hydrogen sulfide in a gas sample 
directly with a standard solution of iodine.
    (b) Apparatus. (See Figure 1.) A 100 or 500 ml capacity Tutwiler 
burette, with two-way glass stopcock at bottom and three-way stopcock at 
top which connect either with inlet tubulature or glass-stoppered 
cylinder, 10 ml capacity, graduated in 0.1 ml subdivision; rubber tubing 
connecting burette with leveling bottle.
    (c) Reagents. (1) Iodine stock solution, 0.1N. Weight 12.7 g iodine, 
and 20 to 25 g cp potassium iodide for each liter of solution. Dissolve 
KI in as little water as necessary; dissolve iodine in concentrated KI 
solution, make up to proper volume, and store in glass-stoppered brown 
glass bottle.
    (2) Standard iodine solution, 1 ml=0.001771 g I. Transfer 33.7 ml of 
above 0.1N stock solution into a 250 ml volumetric flask; add water to 
mark and mix well. Then, for 100 ml sample of gas, 1 ml of standard 
iodine solution is equivalent to 100 grains H2S per cubic 
feet of gas.
    (3) Starch solution. Rub into a thin paste about one teaspoonful of 
wheat starch with a little water; pour into about a pint of boiling 
water; stir; let cool and decant off clear solution. Make fresh solution 
every few days.
    (d) Procedure. Fill leveling bulb with starch solution. Raise (L), 
open cock (G), open (F) to (A), and close (F) when solutions starts to 
run out of gas inlet. Close (G). Purge gas sampling line and connect 
with (A). Lower (L) and open (F) and (G). When liquid level is several 
ml past the 100 ml mark, close (G) and (F), and disconnect sampling 
tube. Open (G) and bring starch solution to 100 ml mark by raising (L); 
then close (G). Open (F) momentarily, to bring gas in burette to 
atmospheric pressure, and close (F). Open (G), bring liquid level down 
to 10 ml mark by lowering (L). Close (G), clamp rubber tubing near (E) 
and disconnect it from burette. Rinse graduated cylinder with a standard 
iodine solution (0.00171 g I per ml); fill cylinder and record reading. 
Introduce successive small amounts of iodine thru (F); shake well after 
each addition; continue until a faint permanent blue color is obtained. 
Record reading; subtract from previous reading, and call difference D.
    (e) With every fresh stock of starch solution perform a blank test 
as follows: introduce fresh starch solution into burette up to 100 ml 
mark. Close (F) and (G). Lower (L) and open (G). When liquid level 
reaches the 10 ml mark, close (G). With air in burette, titrate as 
during a test and up to same end point. Call ml of iodine used C. Then,

Grains H2S per 100 cubic foot of gas=100 (D--C)


[[Page 656]]


    (f) Greater sensitivity can be attained if a 500 ml capacity 
Tutwiler burette is used with a more dilute (0.001N) iodine solution. 
Concentrations less than 1.0 grains per 100 cubic foot can be determined 
in this way. Usually, the starch-iodine end point is much less distinct, 
and a blank determination of end point, with H2S-free gas or 
air, is required.
[GRAPHIC] [TIFF OMITTED] TC01JN92.055

      Figure 1. Tutwiler burette (lettered items mentioned in text)

Subpart MMM [Reserved]