Present compressed air bid alternates as documented comparisons against the specified package—not just lower-priced equipment quotes. Identify each deviation, provide supporting technical information, and show how the proposed change affects installation scope, operating requirements, price, and schedule. Route that information through the project’s substitution procedure before treating the alternate as accepted.
A supplier’s proposed alternate is not an engineer-approved substitution. At Process & Power, we can help contractors define the equipment proposal and identify questions requiring clarification. The engineer of record and the project’s approval process determine whether a proposed design change is acceptable.
Confirm the Substitution Rules Before Pricing the Alternate
Start with the current specifications, equipment schedules, drawings, and addenda. Check the approved manufacturer requirements, substitution deadline, required forms, and submission route. Some projects require review before bidding; others allow a separately identified proposal at a later stage. Don’t assume a post-bid request will be considered.
Also distinguish an owner-requested bid alternate from a supplier-proposed substitution. The bid documents may define an alternate with a specific scope and pricing format. A different compressor package offered by a supplier may require a separate substitution request, even if the estimator calls both options “alternates.”
If the requirements conflict or are incomplete, submit a clarification through the designated project contact. Silence in a specification isn’t approval to change the system.
Build a Requirement-by-Requirement Comparison
The reviewer should be able to find the difference without searching through two full product catalogs. Use the specified package as the baseline and identify the proposed manufacturer, equipment selection, and package boundaries.
For each relevant requirement, document these five items:
Reference: Specification section, drawing note, schedule entry, or addendum.
Specified requirement: What the contract documents require.
Proposed selection: What the alternate includes and its supporting documentation.
Status: Complies, deviates, or requires clarification.
Impact: What changes elsewhere in the project and who must resolve it.
Use “requires clarification” when information is missing. Don’t mark an item compliant simply because a brochure doesn’t address it. Likewise, “equal or better” is not a useful explanation unless the proposal identifies the comparison criteria and supporting evidence.
At minimum, review the equipment’s required flow and pressure, air treatment, storage, controls, electrical requirements, physical arrangement, and service access. Concentrate on differences that affect the specified application rather than copying every catalog feature.
Compare Performance at the Same Conditions
Matching compressor horsepower does not establish equivalent performance. Compare delivered airflow at the required discharge pressure using consistent rating conditions. Explain whether the quoted performance applies to the compressor alone or to the complete package, including treatment equipment and associated pressure losses.
Air quality needs the same attention. Identify the specified moisture, particulate, and oil requirements, including any stated measurement point or operating conditions. An oil-free compressor designation alone does not establish that the complete system meets every air quality requirement.
For the proposed dryer and filtration, confirm the selection basis against the expected inlet and ambient conditions. If those conditions aren’t available, list them as open questions rather than assuming the alternate meets the requirement.
Other differences may be less obvious but still material:
Capacity and standby operation: Does the proposal preserve the required capacity when equipment is unavailable?
Controls: Does it provide the required sequencing, alarms, remote signals, and coordination with existing equipment?
Storage: Does the receiver arrangement match the specified function and configuration?
Installation conditions: Do ventilation, heat rejection, electrical characteristics, and maintenance clearances fit the planned space?
Provide selection data, dimensional drawings, electrical information, controls documentation, and a marked-up package description where relevant. Identify each document’s revision so the reviewer knows which configuration supports the request.
Show Scope and Commercial Impacts Separately
A lower equipment price may reflect a different scope rather than an equivalent package. State whether the proposal includes the receiver, dryer, filters, drains, condensate management, accessories, freight, and startup support. Identify exclusions just as clearly.
Then separate equipment supply from field responsibilities. Unloading, setting, piping, electrical work, controls integration, testing, and startup should each have a defined responsible party or an explicit unresolved assignment. Our equipment proposal should not be read as including those tasks unless they are expressly included in the quoted scope.
Document connection changes and coordination costs even when another contractor will price them. A revised electrical requirement or different connection location can affect the comparison without appearing in the equipment supplier’s price.
Label preliminary budget information as preliminary. A firm equipment proposal should identify its scope, assumptions, exclusions, validity, and applicable commercial terms. State whether delivery information is an estimate or a confirmed commitment, and identify any unresolved approval timing that affects it.
Example: A Dryer Difference That Needs Review
Consider a hypothetical mechanical contractor bidding a facility expansion in Memphis. The specified compressed air package includes a separate dryer and receiver. A supplier proposes a compressor with an integrated dryer, while the receiver remains a separate item.
The integrated arrangement is not automatically unacceptable, but it changes the review. The contractor needs documentation showing that the proposed drying performance meets the project requirements under the expected conditions. The reviewer also needs to understand changes to connections, service access, and whether dryer service affects the availability of compressed air.
The substitution request should explain those differences directly. If the receiver is excluded from the alternate quote, its required scope must remain in the bid comparison. A price difference is not meaningful until the two proposals cover comparable requirements.
Use a Substitution Request Cover Sheet
A concise cover sheet helps keep the technical review and estimating assumptions connected. Include:
Project: Name, Tennessee location, estimator or project manager contact, bid deadline, and required-on-site date.
Document basis: Drawing and specification revisions, equipment tag, and applicable addenda.
Request: Specified package, proposed package, and reason for the substitution.
Comparison: Itemized deviations, compliance evidence, and unresolved requirements.
Coordination: Connection changes, space impacts, trade responsibilities, and startup scope.
Commercial effect: Separate alternate price, exclusions, additional field costs, and pricing status.
Schedule effect: Current delivery information, approval dependencies, and requested review date.
Attachments: Technical data, drawings, marked-up scope, and required substitution forms.
Track the written review disposition and any conditions. Don’t carry a proposed alternate into purchasing as accepted based on an informal discussion or a quotation notation. If acceptance requires revisions, reconcile those revisions with the supplier’s proposal before releasing the order.
Send Us the Specified Scope and Proposed Differences
Preparing a compressed air alternate? Send us the project scope, specifications, proposed deviations, bid deadline, location, and estimator or project manager contact through our Contractor Bids page. We can discuss equipment pricing and the information needed to define our proposal for review. You can also include us in relevant upcoming equipment bid invitations.
Process & Power, Inc.
901-362-5500
1721 Corporate Avenue, Memphis, TN 38132
