Industrial Air Compressor RFQ Checklist

1. Define the project boundary before requesting prices

State whether the RFQ covers a package, complete compressor room, replacement, expansion or turnkey system. Identify the supplier scope: compressor, motor and drive, controls, aftercooler, separator, receiver, filters, dryer, drains, ventilation, pipework, electrical works, commissioning and training. List exclusions. Prices are difficult to compare when one bidder includes treatment and installation while another quotes only the compressor block.

Give the project location, indoor or outdoor arrangement, altitude, ambient range, available electrical supply, noise constraints, lifting access and floor or foundation limits. Identify any hazardous-area classification. Ask suppliers to state assumptions and deviations instead of silently selecting a configuration that cannot be installed or operated at the site.

• New system, replacement, parallel expansion or temporary capacity
• Supply boundary, exclusions, utilities and site responsibilities
• Applicable local codes, pressure-vessel rules and electrical requirements

2. Describe demand as a profile, not a single flow number

Record measured or estimated minimum, normal, average and peak demand, with measurement period and flow reference. Identify shifts, seasonality, start-up events, batch peaks and simultaneous users. Note whether demand is steady, cyclic or burst-driven. Nameplate-only selection can oversize a compressor, while average-only selection can miss pressure collapse during peaks.

For each major user, provide operating pressure at the point of use, expected flow, duty cycle, hose or pipe connection, and whether the user can tolerate a short pressure variation. Separate continuous base load from intermittent loads. Ask the supplier to show the proposed capacity at the specified discharge pressure and reference condition, and to explain turndown, sequencing and storage assumptions. FAD, CFM and normalized flow are not interchangeable unless their pressure, temperature, humidity and standard-condition bases are explicit.

3. Separate pressure, treatment and point-of-use quality

Specify the pressure required where the process consumes air, not merely the compressor’s maximum rating. Include minimum pressure at the least favorable outlet, normal header pressure, allowable transient dip and any pressure-drop budget through the aftercooler, filters, dryer, receiver, valves and distribution. A higher discharge pressure than the process needs can increase energy use and may change treatment and vessel requirements. Ask for a pressure-drop calculation at the stated flow, not a generic promise that the package will maintain pressure.

Write air quality as an end-use requirement. Identify particles, water or pressure dew point, oil and any gaseous or microbiological concerns that matter to the process. ISO 8573-1 classifies compressed-air purity by particles, water and oil and identifies gaseous and microbiological contaminants; it does not by itself prove that a proposed assembly achieves the selected class. Define the sampling location, test method, operating state and acceptance limit. Oil-free compression is a compressor technology choice, not a blanket food-safety or contamination guarantee.

• Required pressure and quality at each critical point of use
• Pressure dew point or other water limit at the stated pressure and ambient conditions
• Filter grades, drain behavior, condensate handling and monitoring requirements
• Sampling location, laboratory or test method, reporting units and acceptance limits

4. Ask for a configuration that fits the duty

The RFQ should invite a justified configuration rather than force an unexamined technology. Ask bidders to identify whether fixed-speed, variable-speed, single-unit, multiple-unit, screw, piston or another arrangement is proposed, and why it fits the demand profile. For variable speed, request the usable control range, minimum stable operating point, efficiency data across relevant loads and minimum-load assumptions. For multiple compressors, request sequencing, lead-lag rotation, redundancy philosophy and behavior when one unit is unavailable.

State the required availability objective without turning it into an unsupported guarantee. Explain whether production can stop during service, whether a standby unit is required, and what capacity remains after the largest unit is offline. Ask for a lifecycle comparison that separates purchase price, expected electricity consumption, consumables, planned service, major overhaul assumptions and exclusions. CAGI’s verification program demonstrates why standardized data sheets and verified performance data are useful for comparison, but participation or a seal is not a substitute for checking the exact proposed model, test conditions and scope.

5. Make the air path and storage relationship explicit

Show the proposed air path from intake to critical outlet. Identify aftercooling, moisture separation, receiver placement, filters, dryer, drains, dew-point monitoring and point-of-use treatment. Ask which components are standard, optional or sized separately. Treatment must match actual flow, inlet pressure, ambient conditions and required quality; a filter or dryer name alone is not a complete design.

Describe existing and proposed receivers by volume, working pressure, location, isolation, drain arrangement and inspection responsibility. A receiver can help absorb short demand peaks and stabilize control, but it does not replace adequate generation capacity or correct a restricted distribution line. Request a simple pressure profile from compressor discharge to the critical user, including component pressure drops at design flow. Confirm whether the quotation includes piping, flexible connections, supports, condensate drainage and safety devices, and who is responsible for jurisdiction-specific vessel compliance.

6. Require a response format that can be compared

Give every bidder a response schedule with one row per requirement. Require a comply, deviate or not-applicable answer, a supporting-document reference and the commercial impact of each deviation. Request drawings, weights, utility loads, electrical data, noise information, connection sizes, foundation loads, control interfaces and included accessories. A model number is not a substitute for a data sheet at the requested operating conditions.

For performance, ask for flow, pressure, input power or specific power, sound measurement basis, operating envelope and test standard. The CAGI verification page explains that its compressor data sheets use standardized performance presentation and that its program uses ISO 1217 for displacement-compressor testing; this is useful context for requesting comparable evidence. If the proposed equipment falls outside a cited program’s scope, ask what equivalent test method and witnessed or certified evidence will be supplied.

7. Put commissioning and acceptance into the RFQ

Define what will be checked at factory and site acceptance. Potential checks include measured flow at the agreed pressure, input power, control response, alarms, noise, pressure drop, dryer dew point and air-quality sampling at named locations. State the stabilization period, site operating condition, instrumentation uncertainty, test responsibility, witness rights and treatment of a failed test. Acceptance criteria should match the quoted duty and reference conditions; a component certificate or generic brochure is not assembly-level proof.

List handover documents: approved drawings where applicable, manuals, spare-parts list, wiring and control diagrams, pressure-vessel documentation, electrical declarations, calibration records, test reports, service tasks and training records. Ask suppliers to identify maintenance intervals as dependent on equipment, ambient conditions, inlet air, duty and operating hours. Do not insert a universal interval when the OEM has not confirmed it.

8. Compare ownership cost and support on the same basis

Request a transparent operating-cost model rather than a single annual saving claim. Provide operating hours, load profile, electricity tariff structure, cooling-water cost if relevant, ambient conditions and expected production changes. Ask the supplier to show assumptions for loaded and unloaded power, control losses, dryer consumption, standby operation, consumables, labor, disposal and major service. CAGI notes that energy can be a major lifetime cost, so purchase price alone is a weak comparison. The model is still an estimate and must not be treated as a performance guarantee.

Ask who will provide commissioning, training, emergency support, parts, monitoring and local service. Request response-time assumptions, exclusions and service-call requirements. Compare like with like: a low quote omitting treatment, installation, commissioning or spares is not equivalent to a complete package.

RFQ submission checklist

Before release, attach a process description, demand schedule, site data, existing equipment information, air-quality requirements, utilities, delivery constraints and response schedule. Mark values as measured, estimated, target, minimum or maximum. Invite bidders to identify missing information and quote alternatives separately. Keep the base bid comparable; show optional redundancy, heat recovery, monitoring, treatment or expansion as distinct line items.

Reject responses that miss mandatory pressure, quality, safety or installation requirements. Then compare performance at the same basis, lifecycle assumptions, service scope, documentation and acceptance method. Record deviations in the purchase order and repeat critical conditions in the approved data sheet.

• Attach a marked-up PFD or air-path description and point-of-use schedule
• Separate mandatory requirements, priced options and supplier assumptions
• Keep the buyer’s measured data and the supplier’s proposed values distinguishable

SELECTION & OPERATION

Frequently asked questions