Why Comparing DN100 Filter Prices Alone Creates Procurement Risk
A lower DN100 price is only comparable against a written duty. Ten items that move the price, three evidence levels, and the six inputs to prepare.
Two quotations for a DN100 filter can differ by a factor of two and both be honest, because the number on the page is not the same thing in each case. One may describe a housing with an element; another may include valves, a bypass, a controller or a differential gauge. One may quote a price per unit at a quantity the project will never reach; another may quote a project price with a lead time attached. Comparing them without normalising the basis is how a purchasing decision becomes a false saving.
01 – Why each channel needs it, and where it is used
| Channel | Role in this decision | Why they need it |
|---|---|---|
| Distribution and wholesale | Compare supplier prices before reselling | Two distributor prices that look different often describe different scopes; reselling on the lower number produces a margin problem at commissioning |
| Contractors and integrators | Price a project against a specification | The bid that wins on a stripped scope is the bid that loses on variations; normalising the basis protects the margin |
| Direct B2B users – farms, estates, municipal green | Compare offers for a known duty | The cheapest offer usually excludes the parts that make the installation work, and those parts appear later |
| Specifiers and influencers – designers, procurement consultants | Make offers comparable | The evaluation table is the designer’s document; if the basis is not fixed, the comparison is arbitrary |
It applies to any project where more than one offer is received for a filtration item: municipal tenders, estate upgrades, irrigation packages and distributor price comparisons. The mechanism is the same in all of them – the quoted number is only comparable when the scope behind it is identical.
02 – How to make a preliminary selection
Write the duty first: peak flow, allowable pressure loss, required grade, water description and cleaning model. Without those five, no two offers can be compared, and the conversation becomes a discussion about prices for things that are not the same.
Then list the scope items explicitly: housing, element, element grade, pressure gauge, differential gauge, valves, bypass, controller, flush route, mounting, documentation and spare elements. Each item that appears in one offer and not the other is a difference in scope, not in price.
Then normalise the commercial terms: quantity basis, MOQ, price validity, lead time, payment terms and the incoterm if the goods cross a border. A price per unit at a quantity nobody will order is not a comparable number.
Finally, ask for the assumption behind each offer: the flow at which the element is rated, the loss quoted, and the grade supplied. An offer that states its assumptions can be checked; one that does not has to be taken on trust, which is not a procurement method.
03 – Comparing the realistic options
The table is the normalisation sheet – the one document that turns several offers into one comparison.
| Comparison line | What to record |
|---|---|
| Duty | Peak flow, allowable loss, required grade |
| Scope | Housing, element, valves, gauges, controller |
| Documentation | Flow rating, grade test basis, materials |
| Commercial | Quantity basis, MOQ, validity, lead time |
| Service | Spare elements, response time, warranty |
Filling this sheet takes an hour and usually removes one or two offers from consideration before price is discussed – because the scope difference becomes obvious, not because anyone negotiated.
03b – What a low price is made of
A lower price can come from four places: a smaller element area at the same nominal grade, a thinner housing, a coarser element than the specification asked for, or a scope that omits gauges and valves. All four are legitimate commercial choices, and all four change the installation. The useful question is not why the price is lower but which of the four produced it.
There is a fifth possibility – a genuine difference in cost structure – and it is the one buyers hope for. Distinguishing it from the other four requires the scope sheet, which is why the sheet is the most valuable page in the procurement file.
04 – What goes wrong, and what still needs confirming
The classic failure is buying the cheaper offer, discovering at installation that the valves and gauges are missing, and finding that the variation to add them costs more than the difference. The second is buying on a unit price at a quantity the project will never reach, then discovering the actual price at the actual quantity.
Items to confirm in writing before award: the scope list, element by element; the flow rating and the grade; the pressure loss at that flow; the documentation supplied; the lead time and validity; and the spare element price for future orders. Those six lines make the next comparison cheap and the current award defensible.
05 – What we can supply and what to send
Delta AgriFlow quotes filtration against a written duty and returns the offer in the same structure the buyer used, so the lines can be compared without translation: Y-pattern disc filters, automatic disc filters, self-cleaning screen filters, media filtration and modular stations.
Send six items for a comparable quotation: peak flow and allowable pressure loss; required grade and the emitter behind it; the scope items you expect; quantity and delivery point; lead time needed; and the documentation required for handover. With those, offers arrive in the same shape.
A second source of price difference is the element itself. Two elements that both claim a 120 mesh rating can differ in area, material and construction, and the difference shows as a cleaning interval rather than as a filtration result. Where the cleaning routine is the site’s constraint, that difference is worth more than the price gap.
A third is the housing’s serviceability. A housing that can be opened without tools and reassembled in order costs more to make and saves time every month. The procurement file should record the service step, because it is the part of the price that returns as labour.
A fourth is documentation. A supplier who provides the flow rating, the grade test basis and the materials data is selling a specification; one who provides a price list is selling an item. On projects with handover requirements, the documentation is part of the deliverable.
A useful habit is to keep the normalisation sheet for the project in the procurement file. When the next project arrives, the sheet is already written, and the comparison takes minutes rather than a week.
None of this argues for buying the most expensive offer. It argues for buying the offer whose scope matches the duty, at a price that is transparent about what it includes – which is the only basis on which two numbers can honestly be compared.
There is also a timing question that belongs in the comparison. An offer with a short validity and a long lead time is not the same product as one with the opposite, and on projects where the installation date is fixed by a planting window, the difference can matter more than the price gap. Recording validity and lead time next to the price turns three numbers into one decision.
A last point on negotiation: the supplier who can explain the four sources of a low price is usually the one who can also explain what the offer does not include. That explanation is worth more than a discount, because it is the only thing that prevents the variation later in the project.
Keep the sheet with the project file; the next comparison will take minutes instead of a week.
A comparison that can be repeated is worth more than a discount that cannot be explained.
06 – Questions, sources and next steps
Why is one DN100 filter twice the price? Usually because the scope differs: housing only versus housing with element, valves, gauges and documentation. The normalisation sheet exposes which it is.
Should I compare unit price or project price? Compare the price at the quantity you will actually order, with the same scope, the same validity and the same lead time.
Is a cheaper element a false economy? Where the cleaning interval is the constraint, yes. Where the load is light, it may be the right choice – which is why the interval belongs in the comparison.
Information boundary
This article describes how the decision is structured. It is not a performance specification and does not state capacity, flow, pressure or service-life values for a specific product. Those values are confirmed per project after a written quotation; manufacturer figures cited are the published values for those products, not project commitments.
Reviewed: 2026-10-26. Next review after supplier specifications are confirmed in writing.
Sources and further reading
- Rain Bird XFA 13 mm dripline datasheet – 120 mesh filtration requirement, 50-350 kPa compensating range
- Netafim Techflow bid performance specification – 120 mesh or finer filtration, disc grades 40-200 mesh
- ISO 9912-1:2004 – Filters for micro-irrigation: classification
- ISO 18471:2015 – Verification of filtration grade
- FAO – Irrigation manual, Chapter 6: drip irrigation
Normalising filtration offers? Send the duty and the scope list through our quotation request.
