Page 480 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Lube, Seal and Control Oil System Best Practices Best Practice 7 .34

Fig 7.34.9 Compressor shaft seal
(Courtesy of IMO Industries)

At maximum operating pressure, however, the valve only passes
3. Flow-through flow
a flow of three gallons a minute since 46 LPM (12 GPM) exit
Minimum ¼ 12 LPM (3 GPM) (occurring at high ATM
through the atmospheric bushing. This type of system is less
bushing flow ¼ 46 LPM [12 GPM]) sensitive to low suction pressure operation since flow through oil
Maximum ¼ 46 LPM (12 GPM) (occurring at low ATM will remove frictional heat around the atmospheric bushing.
bushing flow ¼ 12 LPM [3 GPM])
4. Seal oil supply flow in both cases ¼ 58 LPM (15 GPM) Example 2: Contact type gas side seal e bushing
type atmospheric seal with orificed through flow
As shown in the previous example, the required seal oil
supply at maximum operating speed required to remove fric- The only difference between this type of system and the pre-
tional heat is 58 LPM (15 GPM). At start-up, low suction vious one is that the back pressure is maintained constant by
pressure conditions, the control valve must open to allow an a permanently installed through flow orifice. As a result, the
additional ten gallons a minute flow through to the seal chamber. differential pressure control valve is installed on the inlet side of

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