Buffer sealing gas of tertiary seal gas of a refrigerant centrifugal compressor has been disconnected...what we expect to happen..personally I believed it will damage labyrinths seal.

tertiary seal gas includes a 1 inch line coming from discharge (21 barg) + 2 inches line of Dry seal gas (22 barg). this second is shut. if we want to know the consequences, we need to know what are all functions of this tertiary sealing.

at the moment this gas injected between inside and outside labyrinths. I expect Some one point to leakage of lube oil to the labyrinth seals and damaged the metal.

Mohsen.maddahi [at] yahoo.com

 

DGS is composed of primary, secondary stages and finally is protected from environment by the buffer gas through separation seal which is called some times (tertiary).

There is a cavity between both secondary and separation seals called secondary seal cavity. This way if any oil escaped from the labyrinth seal at the bearing side it will be trapped at this cavity. This cavity is designed to collect and direct this oil to a drain line-may be not connected during construction- and it is advisable to check this cavity periodically to assure the absence of oil and to prevent oil form attacking the DGS. If it happens this will damage the DGS and so its function.