Compressor
How is compressor reliability mathematically defined?
Reliability R(t) is the probability of operating without failure for time t, defined as R(t) = e^(-∫_0^t λ(t) dt), where λ(t) is the failure rate.
What components of a reciprocating compressor require specific reliability evaluation?
Key components include cylinders, pistons, inlet/discharge valves, connecting rods, crossheads, crankshaft, and lubricating units.
Why is improving compressor reliability difficult via maintenance alone?
Reliability is primarily a function of 1st Design and 2nd Production; maintenance can only detect installation errors or liquid carryover, not fix inherent design flaws like low ring life (<8000 hr).
A compressor is a driven mechanical device that increases gas pressure by reducing its volume, classified as positive displacement (e.g., reciprocating, screw) or dynamic (e.g., centrifugal, axial). In reliability engineering, it is critical un-spared equipment where reliability directly impacts profit, with properly selected and monitored compressors achieving over 99.7% reliability.
On the shop floor, compressors are integrated systems including the drive unit, air end, lubrication system, sealing system, and control/protection systems. Maintenance relies on continuous condition monitoring (vibration, temperature, pulsation analysis) for predictive maintenance to detect degradation before failure. In CMMS like ServiceGrid, compressors are tracked via KPIs such as MTBF, MTTR, and OEE to schedule maintenance and manage spare parts, ensuring high availability and minimizing downtime.
Liquid carryover: Ingress of liquid into the compression chamber causes immediate mechanical damage to pistons, rings, or rotors and accelerates wear if not monitored.
Seal and seal oil system contamination: Poor design or monitoring leads to lube oil contamination, causing huge damage to internal components.
Pulsation-induced failure: Inadequate pulsation studies ignoring off-skid piping or off-design conditions create resonance that fails critical components in short timeframes.