Pumps are quoted badly when the RFQ says water pump and a pipe size. Tradinor asks for the duty point, the liquid, the suction condition, and the power supply. The curve either passes through that point or the pump is the wrong one.
Flow, head, and what the liquid is
State flow and head together, and say whether the head includes static lift and pipe loss. Give the suction condition. A pump that meets the discharge head can still cavitate if the suction is poor. State the liquid, the temperature, and solids if there are any. Clean-water bronze and a slurry iron are not the same casting. Seals follow the liquid. A mechanical seal has a flush plan on harder duties. If you do not know the plan, say the liquid honestly and ask the maker which seal they rate.
- Duty flow and duty head, and the minimum and maximum if they vary.
- Liquid, temperature, and solids.
- Suction condition: flooded, lift, or a long inlet.
- Supply voltage and phase, and whether a drive is already specified.
- Submersible or dry-mounted, and the discharge size only as a result.
| Line | Why the price moves | Weak wording |
|---|---|---|
| Duty point | Selects the impeller and the power | As big as possible |
| Liquid | Selects metal and seal | Water, probably |
| Installation | Submersible cable and cooling | A dry motor in a pit |
| Power | kW at the duty, not the next frame up | The largest motor in the catalog |
Sample and nameplate
Read the nameplate flow, head, and kilowatts. They should match the duty you ordered, not a catalog maximum. Confirm materials against the data sheet if the liquid is not clean water. Confirm the cable length on a submersible before the well is closed. Do not throttle a pump to a far corner of its curve and call it the duty. If the duty was wrong, correct the RFQ. A valve used as a permanent design is energy and a seal problem.
What to lock on the order
Put the duty point in the first line of the RFQ and attach the curve you expect the selection to sit on. Add the liquid, the temperature, and a sentence about suction. If the pump is submersible, add the well depth and the cable length. If it is dry-mounted, add the plinth and the coupling or the close-coupled motor preference. Voltage and starting method come next, especially if a soft starter or a drive is already in the panel. Ask for the power at the duty point, not the maximum power on the curve. Seals and materials should be the maker’s recommendation for the liquid you described, written back to you for acceptance. On delivery, read the nameplate duty against the order before the pump goes into the pit. A larger impeller that happens to fit will move the duty and the motor load. Treat that as a new quote, not as a bonus.
Questions buyers actually ask
What is a duty point?
The flow and the head you need at the same time. A pump curve is a line. The duty point is the dot you must sit near.
Why does the liquid change the material?
Clean water, slurry, hot water, and a chemical solution are different wetted parts. Write the liquid and the temperature.
Submersible or end-suction?
Submersible when the pump must live in the wet well. End-suction when it sits on a plinth in a dry room. The motor enclosure follows that choice.