Two compressor quotations can list the same horsepower and still describe different systems. A fair comparison starts with the air your process needs and the scope each supplier includes. Use this checklist before comparing purchase prices.
Match flow and pressure
Write down the required flow and the minimum pressure at the point of use. Ask each supplier to state the delivery rating and its measurement basis at the quoted operating pressure. Keep the units and reference conditions consistent. Record pressure losses through treatment equipment and distribution separately from compressor discharge pressure.
If demand has not been measured, identify which values are estimates. Include normal demand, short peaks, operating hours and any planned expansion rather than using motor horsepower as a substitute for airflow requirements.
Compare package power and controls
Ask for the manufacturer’s performance data at the proposed pressure. Where available, use a CAGI-format data sheet to compare rated flow, package input power and part-load behaviour. Check what is included in the stated power figure. Variable speed is a control option to assess against the actual demand pattern, not an automatic guarantee of savings.
Record supply voltage, phase and frequency. Identify whether starters, drives, disconnects, wiring and electrical connection are included or excluded.
Make air treatment a separate line item
- Required air quality and the process or equipment specification it comes from.
- Dryer type, duty conditions and required pressure dew point.
- Filters, condensate drains and condensate handling.
- Receiver volume, location and connection scope.
- Pressure drop and service access for the complete package.
A compressor-only price cannot be compared directly with a package that includes a dryer, receiver and filters.
Compare the installed scope
List freight, unloading, rigging, foundations or supports, piping, ventilation, electrical work, commissioning and training. Ask who is responsible for each item and which services require separate qualified contractors. State any shutdown window, backup-air requirement and access restrictions.
Check the commercial details
Compare currency, taxes, quote validity, availability, delivery assumptions, warranty terms and service arrangements. Ask for maintenance intervals and expected consumables, and separate documented values from estimates. Do not add an assumed energy rebate to the comparison unless eligibility and approval have been confirmed.
Prepare the comparison
Use the compressed air calculators and quote-comparison tools to organise the inputs. The compressor room planner helps map the equipment and utilities. Browse rotary screw compressors, or discuss a compressed air audit when the demand profile needs measurement.
Discuss your compressor requirements with PRP Reps and Suppliers.
Reference: CAGI performance verification and data sheets. Calculators support planning; quotations and equipment selection require the actual site conditions.
When the requirement is instrument air
Include the required air-quality specification and point-of-use conditions with the package request. The custom instrument air package enquiry checklist collects the demand, pressure, quality, site and delivery information needed to discuss a complete scope.