ANGI CNG Compressor – Model NG 50, Inlet 9-13 psi, Discharge 5000 psi, Flow 75 scfm

What capacity and discharge pressure does it actually deliver?

This unit delivers 75 SCFM at 4,500 PSI discharge pressure from a 9–13 PSI suction supply, with a maximum allowable working pressure of 5,000 PSI. The NG-050 model designation indicates ANGI's 50 HP frame, which in this configuration targets light-duty fleet fueling or time-fill applications rather than fast-fill.

What drive, power and cooling does it require?

The compressor is driven by a 50 HP Baldor-Reliance Super E motor (1775 RPM, TEFC, 94.5% efficiency) with multi-voltage capability: 230/460/190/380 VAC at 116/58/138/69 amps respectively. Control systems require 120 VAC single-phase at 10 amps and 24 VDC at 5 amps. CNG compressors in this class are typically air-cooled via fan and require adequate ventilation; confirm ambient temperature limits and whether any intercooler or aftercooler maintenance has been performed at this hour interval.

What are the running hours and what has been rebuilt?

The unit shows 14,400 hours with all required periodic maintenance completed per the listing, and PRVs recertified through July 2028. No specific rebuild history is mentioned—ask the seller for valve, packing, and piston ring replacement records, as reciprocating CNG compressors typically require valve service every 8,000–12,000 hours and piston components between 15,000–20,000 hours depending on gas quality and duty cycle.

What should I inspect on a used compressor before buying?

Inspect all four stages for valve leakage, scoring on piston rods, and packing condition; run the unit under load and monitor interstage pressures, temperature rise, and vibration. Check the crankcase oil condition and sample for metal particulate, verify PRV pop-off pressures match nameplate settings, and review maintenance logs for compressor faults, unplanned shutdowns, or gas quality issues that may indicate hidden wear. Confirm the Parker inlet filter element condition and verify the surge tank and all pressure vessels have current inspection stamps if your jurisdiction requires periodic requalification.