Do not assume the old motor size is correct
Factories change over time. Production equipment is added, removed or modified, while leaks and pipe restrictions grow. The existing compressor may be oversized, undersized or compensating for a distribution problem. A replacement should be based on current demand.
Collect controller and operating data
Record loaded hours, unloaded hours, starts, alarms, pressure set points and service history. Where possible, log system pressure and flow through complete production cycles. Compare day, night and weekend demand to identify base load and leakage.
Walk the distribution network
Inspect main headers, ring mains, dead ends, undersized drops, flexible hoses, drains and isolation valves. Measure pressure at the compressor and at critical users under load. A large pressure difference is often a network issue, not a compressor capacity issue.
Review treatment and pressure drop
Dryers and filters can become restrictions when undersized or poorly maintained. Check differential pressure, inlet conditions, drain operation and bypass arrangements. The replacement compressor may deliver more flow and expose inadequate treatment equipment.
Plan control and redundancy
For multiple compressors, review sequencing and which machine should carry base load or trim demand. Consider how production continues during planned service or a breakdown. Redundancy may justify two smaller machines rather than one large unit.
How we turn the audit into a proposal
We combine measured demand, process pressure, equipment condition and future plans. The proposal can compare one-for-one replacement, VSD trim, multi-compressor sequencing, receiver changes, dryer upgrades and pipework improvements. The goal is reliable air at the lowest practical lifecycle cost.
Use the free calculators
Build an initial estimate for compressor demand, receiver size and electricity cost, then send the result to our team for verification.
Frequently asked questions
The period should capture normal production cycles, shift changes, cleaning and any peak processes. One day may be insufficient for variable plants.
Yes, off-shift flow and compressor cycling can indicate leakage, but isolate legitimate consumers before drawing conclusions.
Assess its capacity, condition, pressure drop and required dew point against the new compressor flow before deciding.
Technical references
This guide is educational and uses principles reflected in manufacturer and industry guidance. Final equipment selection must be checked against the selected model’s data sheet and site conditions.