Page 290 - Pipeline Rules of Thumb Handbook

Gas—Compression 277

Nomograph aids in diagnosing compressor cylinder ills

B. W. Robertson, Tennessee Gas Pipeline Co., Houston

Compressor cylinders, like people, develop a fever when Nomograph 1 has been successfully used for a number of
they are sick. Unlike humans, however, the normal tempera- years, although it is slowly giving way to electronic equipment.
ture (suction) is not constant. The trick of using temperatures Nomograph 2 may be finished by completing the suction and
to determine malfunctions lies in determining the correct discharge temperature scales according to the following
starting position. formulas:
To determine the starting position, it is necessary to know
(
the true k value of the product being pumped. The k value Suction t i : = . 8 557r Log t s + 460 ) - 23 .135r + . 2 51 in.
may be obtained from measured pressures and temperatures
above base line
according to the formula:
(
Discharge: t = 23 .067r Log t d + 460 ) - 62 .65r in .
-
kI above base line
TT1 = ( P P1)
2
2
k k
where r =
k -1
where the subfix 2 refers to discharge conditions and the 1 to
suction, and all values of P and T are absolute. 1 and Logs are to the base 10.
The preferred time to obtain this k would be with new
equipment, or from data obtained when the equipment was
new. The next best time would be with newly overhauled Reference
equipment. Lacking either of these data, any values of k must
be considered to contain some malfunctions, and any unnec- 1. Virgil Moring Faires, Applied Thermodynamics, 11th
essarily high numbers should be discarded. Printing, 1946, p. 43.

Nomograph 1. To determine starting position, it is necessary
to know the true “k” value of the product being pumped. The “k” Nomograph 2. This nomograph may be finished by complet-
value may be obtained from measured pressure and tempera- ing the suction and discharge temperature scales according to
tures according to the formula given. the formulas given.