Page 189 - Reciprocating Compressors Operation Maintenance

Operation and Maintenance of Reciprocating Compressors 175

Discharge ^_^
Pressure "~*
Atmospheric
Suction *~ •*" / Pressure
Pressure I
1 2 3 4 5 6 7 8
FIGURE 3-35. Condition 1. First pair of rings seals completely.

Condition 2. The suction pressure is sealed by the last pair of rings and
the discharge by the first. Such a condition is believed to be transitory
between Condition 1 and Condition 3.

Discharge
Pressure

FIGURE 3-36. Condition 2. First pair of rings seals discharge. Last pair seals
suction pressure.

Condition 3. This is a breakdown of suction pressure in increments
across the rings, with each increment reducing the differential pressure
and consequently the amount of leakage by any pair of rings. The dis-
charge pressure is generally sealed by the first pair of rings. Should pres-
sures higher than suction exist beyond the first pair of rings, it would leak
back to the cylinder on the next suction stroke because the rings will seal
only in one direction—with the radial ring facing the pressure.

Discharge
Pressure *"[""]
\\ .Atmospheric
Pressure

FIGURE 3-37. Condition 3. First pair of rings seals discharge. Suction pres-
sure breaks down through packing.