Specifying a Filter Press: The Data Sheet Buyers Must Complete Before Asking for Quotes

Send three suppliers the same one-line inquiry — “a filter press for 500 m³ of sludge a day” — and you will receive three different machines at three different prices, each of them defensible. The reason is printed on the suppliers’ own forms. A missing value on a filter press questionnaire is not left blank: Enviro Solutions’ form carries a “Default if Unknown” column, under which feed solids default to 2 percent and cake dryness defaults change with the sludge family. Enviro Solutions A thin data sheet does not slow the quotation down; it transfers the sizing assumptions to the seller, and the assumptions are what you end up comparing. This guide works through the data blocks that manufacturer questionnaires converge on, and ends with a data sheet you can copy into your next inquiry.

The questionnaires agree on the shape of a complete inquiry

Two manufacturers’ forms — M.W. Watermark’s Filter Press Questionnaire / Process Data Sheet and Enviro Solutions’ Filter Press Questionnaire — ask for near-identical inputs, and MSE Filterpressen’s published selection criteria land on the same list: medium type, solids content and particle size, target filtrate quality, daily throughput and batch frequency, automation requirements and lifecycle costs. M.W. Watermark Enviro Solutions MSE Filterpressen Grouped, the fields form six blocks:

Data block	What the supplier needs from you
Slurry identity	Source and composition; solids content; particle size; pH; specific gravities
Slurry behaviour	Solids type (slimy, fibrous, oily, pasty, compressible); temperature range; abrasiveness
Duty	Volume or dry-solids load per day; process hours versus press hours
Targets	Cake dryness; filtrate destination; cake destination; cake washing, yes or no
Scope and configuration	Feed pump in scope?; automation level; ATEX, corrosive or high-temperature conditions
Verification	A representative sample; lab or pilot testing before final sizing

Slurry identity: the numbers the machine is sized from

Feed solids, stated as a range. This is the most consequential blank on the form. Enviro Solutions publishes a typical range of 2 to 15 percent for feed solids, with 2 percent as the default when the buyer does not know. Enviro Solutions The arithmetic shows why the range matters more than the headline volume: at a slurry density of about 1 t/m³, 500 m³ a day is roughly 500 tonnes of slurry — 10 tonnes of dry solids a day at 2 percent, but 75 tonnes at 15 percent. Same inquiry line, a sevenfold difference in the load the press must actually process. (This article’s calculation, from the cited form’s published range.) State the typical value and the worst week, not the best day.

Particle size. MSE lists particle size alongside solids content as a selection input, and ANDRITZ’s sample testing includes a professional analysis of sludge and particle size distribution before sizing begins. MSE Filterpressen ANDRITZ If you have no distribution curve, say so and offer a sample for measurement (below) instead of guessing one.

Chemistry and character. Both questionnaires ask for the specific gravity of the slurry and of the solids, and M.W. Watermark asks for pH — with the acid or base defined when the value falls outside 6 to 8 — and for slurry temperature as a minimum and maximum. M.W. Watermark Enviro Solutions The same form classifies the solids themselves with checkboxes — slimy, fibrous, oily, pasty, compressible — because character, not just quantity, drives cloth behaviour and cake release. A slurry described only as “wastewater sludge, 3 percent” leaves all of this to be assumed.

Duty and targets: what “done” means

Volume is not load. Enviro Solutions asks for tons of sludge generated per day and the hours worked in a 24-hour day alongside the batch volume; M.W. Watermark asks for batch size in gallons and the days allowed to complete a batch. Enviro Solutions M.W. Watermark Give both the wet volume and the dry-solids tonnage; the press is sized on the second.

Process hours are not press hours. M.W. Watermark’s form asks for the process schedule and, separately, the press operating time available, in hours per day and days per week. M.W. Watermark The gap between the two sets how many cycles per day the machine must turn — and cycle time cannot be assumed, because MSE puts standard cycles anywhere from 30 minutes to several hours depending on slurry viscosity, target cake dryness, membrane or washing steps and the level of automation. MSE Filterpressen

The dryness target is your decision, so state it. When the buyer stays silent, Enviro Solutions’ form defaults the expected cake dryness by sludge family: 20 percent dry solids for biological sludge, 32 percent for metal hydroxides, 45 percent for calcium sludges. Enviro Solutions If your target is set by disposal cost, transport weight or a reuse specification, write the number and the reason; otherwise the quotation prices somebody else’s target.

Destinations and washing. The same data sheet records the process goal for both outputs — filtrate as product, discharge to drain or recycle; cake as product, landfill or recycle — and asks whether cake washing is required, noting that washing pumps a solution through the formed cake to remove salts, impurities and dissolved solids. M.W. Watermark Washing is a specification change, not a footnote: it belongs in the inquiry, not in a clarification round after prices are in.

Scope boundaries. Enviro Solutions’ questionnaire ends with a single checkbox — “Include sludge feed pump in quote? Yes / No” — that changes what the quoted number covers. Enviro Solutions Draw the same line for tanks, cake conveying and installation, item by item, so the quotations you compare describe the same scope.

Configuration context: declare the conditions, let the supplier size the machine

Do not lead the inquiry with a plate size or a filtration area. Enviro Solutions states the purpose of its form plainly: provide the data “so an Enviro Solutions associate can calculate what size of filter press is needed”. Enviro Solutions Chamber volume and filtration area are the supplier’s output from your data; prescribing them in advance freezes someone else’s assumptions into your specification. (Replacing an existing press like-for-like is the honest exception — say that is what you are doing.)

What you should declare is the duty context the price depends on. MSE lists automation requirements among its selection inputs — its presses run from semi-automatic to fully automated, with options such as automatic plate shifting, cloth-washing systems and drip trays — so state the operating model you expect, attended batch or unattended cycles, rather than leaving the automation level to be guessed. MSE Filterpressen The same maker’s cost drivers include the process requirements — ATEX, high temperature, corrosive media — and plate materials from polypropylene to stainless steel and special alloys. Declaring an abrasive or corrosive duty up front prices the plates and cloths honestly in the base quote instead of surfacing later as a variation.

Prove it on your slurry before the final number

Every route above ends at the same place: a sample. M.W. Watermark’s sampling instructions ask for a 5-gallon sample that is representative of the waste stream to be treated on an ongoing basis, taken from the midpoint of the holding tank or sump, with any floating oils or suspended solids the sample does not capture noted on the form, and the safety data sheet included. M.W. Watermark The maker runs tests on the submitted sample to determine treatment, chemicals, dosages and conditions, returns an analytical report, and offers 250 mm pilot units for on-site testing. M.W. Watermark

The pattern is the same at the heavy end of the market: ANDRITZ describes sample testing — on site with a mobile lab or at its laboratory — in which sludge and particle size distribution are analysed so performance can be predicted and the right number and size of presses determined for the buyer’s target, with a pilot filter press available on request. ANDRITZ MSE likewise supports selection with lab analysis and pilot testing, including cloth trials before full-scale deployment. MSE Filterpressen A quotation preceded by a test on your slurry carries a measured cycle time and a measured cake dryness. A catalogue quotation carries defaults. Ask each bidder which of the two you are holding.

The data sheet: copy this into your inquiry

1. Slurry source and the process it comes from; composition of the solids and of the liquid.
2. Feed solids content, percent by weight — typical value and range, including the worst week.
3. Particle size distribution, or a note that a sample is offered for the supplier to measure.
4. pH; if outside 6–8, the acid or base involved.
5. Specific gravity of the slurry and of the dry solids.
6. Solids character: slimy, fibrous, oily, pasty or compressible; abrasive content where present.
7. Slurry temperature, minimum and maximum.
8. Daily duty: wet volume per day and dry-solids tonnes per day; batch size and batch frequency where the process is batch.
9. Hours: process operating hours per day and days per week; hours per day the press itself may run.
10. Cake target: required dry-solids content, and what sets it — disposal, transport or reuse.
11. Filtrate requirement: destination (product, discharge to drain, recycle) and any clarity or solids limit.
12. Cake washing: required or not; if required, what must be washed out.
13. Conditioning: chemicals or flocculant currently used, with dosages — or state that dosing is to be determined by test.
14. Configuration context: automation level expected; corrosive, abrasive, high-temperature or ATEX conditions; any material constraints.
15. Scope boundaries: feed pump, tanks, cake conveying and installation — in or out, item by item.
16. Verification: a representative sample is available (volume and sampling point), and lab or pilot testing is expected before the final quotation.