PSA Nitrogen Selection: Flow, Purity and Normal-Volume Basis

Compare a defined duty, not a collection of maxima

A nitrogen quotation needs a common comparison basis before its flow figure is useful. A larger published capacity cannot settle whether the offered package supplies the required quality at the required delivery conditions. The request should connect flow, purity definition, pressure and feed-air conditions to one documented operating point.

Build a guaranteed-point schedule rather than a brochure-summary column. The schedule below is a purchasing tool: it requests the supplier's stated performance and boundaries. It does not calculate generator capacity, air consumption or a process operating procedure.

Keep four source statements separate

The SMC custom-package page lists a family flow envelope of 10–10,000 Nm3/h and pressure of 5–10 bar without identifying gauge or absolute pressure. Its technical page states purity of 95–99.9995% on an N2+Ar basis. These separate ranges do not promise their endpoints together.

The surface-installed coal-mine DT-series page lists DTD-200/0.8 at 200 Nm3/h, at least 98% purity and 0.5–0.8 MPa. That row leaves feed-air conditions, pressure convention and argon treatment unspecified; it is not general oilfield qualification. The company FAQ gives 0 degrees C and 0.101325 MPa as its general normal-volume basis. An issued quotation should still repeat its own agreed basis.

Build the guaranteed-point schedule

Keep a supplier-response column beside these questions. A blank response is an unresolved requirement, not an invitation for the buyer to fill in the most favourable catalogue value.

Diagnose a superficially complete quotation

In a fictional comparison, Offer P copies the largest family flow, the highest stated purity and the top pressure into one row. Offer Q identifies a proposed model but uses “normal” without defining its reference state. P appears more detailed, yet its combined operating point is unsupported. Q names an item, yet its flow basis is incomplete.

Return different questions to each bidder. Ask P for a single configuration-specific guarantee with the associated feed and delivery conditions. Ask Q to state the reference conditions and connect them to its guarantee. Do not normalize either quotation using an assumed conversion or treat a named model as proof that the missing conditions are resolved.

The review can proceed in parallel with commercial questions, but the performance comparison should remain open until the basis is explicit. This avoids rewarding a quotation for filling every cell with unrelated maxima.

Give the package boundary its own schedule

Performance and supply scope are linked but not interchangeable. Identify air compression, drying and filtration, generation equipment, buffer vessels, analysis and any boosting equipment as included, excluded or separately priced. Ask who supplies each utility interface and which controls are part of the offer.

The FAQ discusses air treatment and sensitivity to inlet pressure and temperature; it does not supply a universal consumption guarantee. Request the utility balance for the offered point instead of estimating it from a generic process description. A family illustration cannot establish that a compressor, analyser or communication protocol is included.

When alternatives are proposed, compare them against the same requested duty and boundary. A change in package scope should be visible as a deviation, not hidden inside a revised total price.

Send a basis that bidders can answer

Refer to the PSA nitrogen package page and use the RFQ Builder to send the schedule, demand profile and available utilities. Request the guaranteed point and exclusions together.

The image is an AI-generated category reference, not a photograph of DTD-200/0.8 or a verified process arrangement. Neither the catalogue examples nor this comparison method establishes stock, manufacturer authorization or project certification.