Municipal purchasing
Writing a Filter Cartridge Specification
A checklist for writing a cartridge specification that gets comparable quotes, with room for the buyer's own acceptance rules.
Why a specification matters
Two cartridges can look the same in a catalog and still behave differently in your housing. A clear specification lets every supplier quote the same thing, and lets you compare the answers without guessing. This page is general purchasing guidance, not legal or engineering advice; your agency's own rules come first.
Name the product you want
If you buy a specific product today, name the manufacturer and the exact part number. This is the clearest way to say what you want. Only add 'or equal' if your agency allows alternatives, and then say how an alternative will be judged.
Describe it, so an alternative can be checked
List the things that decide whether a different cartridge would work.
- Outside diameter and overall length.
- Micron rating, and whether it is nominal or absolute. These are not the same.
- Filter material, for example polypropylene, and the construction: string-wound, melt-blown, pleated, carbon block.
- End style and seal: open ends, flat gasket, o-ring, spring seat or fin end.
- Housing make and model.
- Flow rate and pressure limits, if your design depends on them.
- Temperature limits, if they matter at your site.
Certification, stated exactly
If you need a certification, name the standard, the exact product it must cover, and the document you want to see. A certification for a product family does not always cover every size in it, and some listings cover only the materials. Say what you need, and ask the bidder to supply the listing or the manufacturer's statement.
Quantity, units and delivery
State the quantity and the unit: single cartridges or cases, and how many per case. Give the delivery address and the date you need the order. If you buy the same part regularly, say how often, so the quote can reflect it.
Say how alternatives are judged
Decide before the bid whether an alternative is allowed, who judges it, and what evidence you need, for example the data sheet and the certification listing. Write that in the specification so every bidder works from the same rule.
Send it to us
Send the specification, a filter list, or a spreadsheet with the request. A person reviews it, checks the part numbers against the manufacturers' published specs, and tells you what we can supply and what we cannot.
Next steps
Send us one part number. We'll take it from there.
No account, no minimum, no sales call required to get a number. Tell us what you buy today and we'll come back with available options and case pricing on what we can supply.