Chemical Pump Selection Guide: Risk, Medium and Duty Point — in That Order

Most selection failures we see come from running the decision backwards: pick a familiar pump type, then hunt for a material that survives the fluid.

This guide walks the order that works — risk first, medium second, duty point third — gives the envelope each of our 13 pump families covers, and states plainly where our coverage stops.

What is the pump actually being asked to do?

Nine inputs decide everything downstream: medium and concentration, temperature, flow, head, viscosity, solids content, shear sensitivity, a zero-leakage requirement, and a self-priming requirement. With all nine, the shortlist is usually obvious. Miss two or three, and the answer keeps moving.

The selector asks for these nine. It does not ask for Cv, NPSH margin, shaft deflection or seal-flush plans — those are hydraulic and mechanical design, and they sit outside a screening tool.

Which pump family does the duty pick?

Our library holds 13 pump families. Two rules do most of the work: viscosity above 500 cP moves the answer from centrifugal to displacement, and solids above 3% stop the centrifugal branch.

Two of those ceilings were revised downward after we compared them against manufacturer data and found our figures too generous.

Submersible sewage pumps moved to 40°C, where five manufacturers' published data agree. Slurry pumps moved to 90°C on the metal-wetted-parts basis. Both changes are recorded in the data set's change log, and both are enforced by automated tests so they cannot drift back.

How does the medium fix the material?

Three rules carry over from the compatibility chart: a high-cost alloy is not automatically the safe answer, concentration belongs in the input rather than in a footnote, and the temperature figure is a boundary of the rating rather than a design target.

The full matrix is in Article 1 rather than repeated here.

A high-cost alloy is not automatically the safe answer. For hydrochloric acid, sodium hypochlorite and ferric chloride, our matrix returns X for 304, 316L and duplex — and for some of those media, X for Hastelloy and titanium too. The passing answer is frequently a fluoropolymer.

Concentration belongs in the input, not in a footnote. Sulfuric acid is three different fluids at 93–98%, 50–80% and below 50%, and our matrix treats them as three rows with different answers.

The temperature is a boundary of the rating. Do not design to it. If a duty point sits just under one of our temperature figures, that is a reason to open the handover, not a reason to proceed.

Where do the recommended ranges sit against published manufacturer ranges?

Below them, in every case where both sets exist: single-stage end-suction pumps are catalogued to 215–275 m of head and 1,650–4,540 m³/h against a recommended range that stops at 150 m (492 ft) and 400 m³/h, and the fluoropolymer-lined and mag-drive figures here are 150 °C and 250 °C against published 180 °C and 300 °C.

This is the part a selection guide normally leaves out, and it matters before you read any figure in the table above as a limit of the equipment.

Single-stage end-suction pumps are catalogued by international manufacturers to 215–275 m of head and to 1,650–4,540 m³/h. The recommended range here stops at 150 m (492 ft) and 400 m³/h.

Fluoropolymer-lined centrifugal pumps are published up to 180 °C by at least one European specialist, and mag-drive pumps up to 300 °C by one manufacturer — both are catalogue figures for specific models rather than type-test results. The recommended figures here are 150 °C and 250 °C.

Read the two sets of figures as answering different questions. The published figure is what a manufacturer can supply for a specific duty. The figures in the table above are the range over which this tool returns an automatic answer, chosen on the conservative side.

The consequence is that roughly 31% of duty points produce an automatic report and 69% end in a handover to the manufacturer's engineering team. If your duty point sits above one of the recommended ranges, the tool says so and routes the enquiry. It does not decline it.

What readers assume, and what the guide actually says

Common questions about pump selection

How long does the whole selection take? The arithmetic is immediate. The variable is how long you spend on the material questions, and those are usually settled by the medium and the concentration.

Can I select a pump without a manufacturer's data? You can narrow the family and the material family. You cannot complete a selection, because the pump curve, the seal arrangement and the lining specification come from the manufacturer.

Why does the tool ask for concentration but not for °Bé? Because a concentration figure in percent is unambiguous, and a °Bé input would produce a handover in nearly every case for the buyers most likely to use it. That is a worse experience than asking a percentage.

Does a report from this tool commit anyone to anything? No. It produces a specification sheet you can send to a supplier. It contains no price, no lead time and no supplier recommendation, by design.

What this article does not cover

Note that this guide does not size impellers, calculate system head, specify seal arrangements or select a control philosophy for a dosing package. It narrows a duty point to a pump family and a wetted material family. Everything mechanical comes from the manufacturer.

Where the next constraint sits

A family and a wetted material family are the end of the screening route, and the step that most often overturns them is the medium itself — the concentration bucket and the temperature at which a rating stops holding. Chemical Compatibility Chart for Pumps: What the Grade and the Temperature Actually Mean works that gate cell by cell.

The threshold in this guide that carries the most weight and the least explanation is the 500 cP viscosity switch, which is a recommendation boundary rather than a limit of any centrifugal machine. Centrifugal vs Positive Displacement Pumps: What the 500 cP Line Really Means separates the two.

Two duties take the same set of inputs to a point where the machine class changes rather than the family: CO₂ Injection Pumps: Why the Clearance Volume Decides the Efficiency and Liquid Hydrogen Pumps: What the −253 °C Duty Demands.

Sources