Calculators›Capacity Control
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Capacity Control Calculator

Reciprocating Compressor Turndown & Power Savings

Capacity Control Analysis
Configure your reciprocating compressor and control methods to calculate achievable capacity steps and estimate power savings compared to bypass control.

Compressor Configuration

Double-acting has HE and CE ends
hp
Power at 100% capacity

Control Methods Available

Unload individual cylinder ends
Additional clearance volume per end
Speed range for capacity control

Operating Target

%
Target operating capacity
hrs/yr
$/kWh

Capacity Control Methods

Method Type Power Savings Range
Suction UnloadersSteppedProportionalSteps by end
Fixed ClearanceSteppedProportional15-35%/pocket
Variable ClearanceSteplessLoss-freeContinuous
Speed ControlSteplessLoss-free70-100% typical
BypassSteplessNone (100% loss)0-100%

Learn the Theory

Understand capacity control methods, efficiency impacts, and selection criteria

Read Engineering Guide

Control Method Notes

Suction Unloaders: Most common method. Power reduction nearly proportional to capacity reduction. Negligible losses.
Clearance Pockets: Power proportional to capacity. Fixed pockets give discrete steps; variable pockets allow continuous control.
Speed Control: Loss-free method. Limited to 70-100% range typically due to driver constraints.

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