Reciprocating compressor
A reciprocating compressor uses a piston moving back and forth in a cylinder. It is a positive-displacement mechanism: the working chamber captures gas and reduces its volume.
Guide
ContentsPiston, cylinder and valves
As the chamber expands, gas enters through the suction valve. The return stroke compresses the trapped gas; the discharge valve opens when the pressure difference permits delivery. A crankshaft and connecting rod commonly turn rotation into piston motion. Linear-drive constructions move the piston by another drive arrangement.
Displacement and actual delivery
Gas remains in the clearance space at the end of a stroke and expands before fresh gas enters. Leakage, valve losses and heating also affect delivery. Consequently, piston displacement alone does not determine refrigerant mass flow or cooling capacity. Use model performance at the required suction and discharge conditions.
Enclosure and capacity control
Reciprocating mechanisms may have hermetic, semi-hermetic or open-drive construction. Supported control can include cycling, speed variation or cylinder unloading. Unloading reduces the active compression duty of selected cylinders; it requires the model’s intended mechanism and permitted operating range.
Liquid return and service
Excess liquid entering a compression chamber can produce damaging mechanical loads and dilute lubricant. A semi-hermetic cover permits access but does not prove a repair is viable. Diagnose the circuit and check valve, bearing, motor and oil condition using the applicable service procedure before choosing repair or replacement.
Prepare a compressor request
Pressure conversion and pressure-ratio calculation · model selection unavailable
The pressure tool converts the supplied values and calculates the absolute discharge-to-suction pressure ratio. The request form records other requirements. Neither function selects a compressor, calculates capacity or confirms a refrigerant cycle, diagnosis or interchangeability.
For a technical review, identify the exact model and refrigerant, duty and rating conditions, electrical supply and control, oil, dimensions/connections, and the reason for replacement or service. Missing information remains unknown.
Selection / replacement · Service
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Absolute pressures and pressure ratio
Use suction and discharge pressures for the same stated operating condition and compatible measurement definitions. This is a pressure calculation; it does not check whether a compressor can operate at those pressures.
Method: 1 bar = 100 kPa; 1 MPa = 1000 kPa. Convert each input to kPa. For gauge pressure, p(abs) = p(gauge) + p(atm). For absolute pressure, use the entered value directly. r = p(discharge, abs) / p(suction, abs); r has no unit.
Both absolute pressures must be positive. Enter a positive absolute atmospheric pressure whenever either input is gauge. A negative gauge reading is allowed if its absolute pressure remains positive. Atmosphere is never assumed.
Example: suction 2 bar absolute and discharge 8 bar absolute give 200 kPa, 800 kPa and r = 4. The same result follows from 1 bar gauge and 7 bar gauge with an explicitly supplied atmosphere of 1 bar absolute.
The calculation does not provide cooling capacity, power, discharge temperature, an operating envelope, refrigerant/oil compatibility, diagnosis or a replacement model. Pressure sources, measurement uncertainty, operating stability and model limits remain unverified. Displayed results are rounded; extreme values outside finite numeric precision are rejected.