A quote that lists a 100 mm outlet has not necessarily offered a pump with 100 mm solids passage. These are different dimensions, and neither tells you how the pump will handle a strip of cloth. Before comparing sewage-pump prices, separate the pipe connection, the clear path through the wet end and the actual material in the wastewater.
Three questions hidden inside “non-clog”
Free passage describes the size of a solid sphere that can move through the pump without jamming. Outlet diameter describes the discharge connection. Fibre handling concerns how material such as cloth and string interacts with the impeller. A spherical-passage rating is useful evidence, but it does not describe every ragging condition.
- Connection: What flange, outlet diameter and mating coupling are supplied?
- Passage: What spherical solids size is stated for this exact hydraulic selection?
- Wastewater: Are the troublesome solids hard particles, sand, cloth, string, grease or a mixture?
Channel-impeller construction matters because fibres can catch at vane leading edges. Ask for the offered impeller arrangement rather than accepting “non-clog” as the complete answer. Cutter and vortex arrangements solve different problems; the wastewater description must come before the choice.
Two catalog examples that show why the distinction matters
A family range is not a rating for every frame
The AsiaSun QW record describes a family with stated solids passage from 5 to 125 mm, depending on the selection. The standard catalog conditions include liquid up to 40°C, pH 4–10 and solids below 2% by volume. This does not mean every QW pump passes 125 mm solids, or that the largest solids figure is available at every duty point.
For a quote from AsiaSun, ask the bidder to identify the exact pump, its passage dimension and its curve together. Keep a family-wide maximum out of the acceptance schedule unless the offered construction explicitly carries that rating.
A named duty point does not supply a missing passage value
The Peiyuan 50WQP10-10-0.75 record has a catalog row of 10 m³/h flow, 10 m head, a 0.75 kW motor and a 50 mm outlet. That row identifies an outlet and duty rating. It does not establish a 50 mm spherical passage. The WQP family describes stainless construction and channel-impeller arrangements; the passage of the exact offer still needs confirmation.
Use the Peiyuan factory profile to review its other series, then request the model-specific passage and construction. Neither example is a performance test or a declaration that the two pumps are interchangeable.
Build a comparison that exposes missing answers
Give each bidder the same schedule. Keep separate fields even when the numbers happen to match. A blank should mean “awaiting confirmation”; do not fill it from a model prefix or a neighbouring catalog row.
- Required duty: state flow and total head, operating range, liquid level variation, supply frequency and voltage. Require a marked curve for the offered impeller.
- Connection: name the discharge size, flange standard, coupling and existing pipe connection. Obtain a dimensioned installation drawing.
- Solids: state maximum observed hard-particle size and concentration, plus the kind and approximate length of fibres. Include recurring blockage history when available.
- Hydraulic construction: request impeller type, spherical free passage in mm and the model/configuration to which that value applies.
- Service conditions: include temperature, liquid chemistry, abrasive material, wet or dry installation, duty cycle and required monitoring.
- Exceptions: ask the bidder to list requirements it cannot meet, instead of replying only “complies”.
A purchase-review example
Suppose the pipe connection is already fixed and the wastewater contains cloth as well as hard particles. One bidder repeats the outlet dimension as its solids answer; another gives a passage dimension for a named impeller but has not addressed cloth. Neither response is complete. Send the first bidder back for the separate passage rating and the second for an explanation of the impeller selection for the stated fibres.
Only after these gaps are closed should you compare hydraulic performance, motor loading, installation fit and maintenance provisions. This is a review sequence, not a rule that the largest passage or largest motor is automatically the best purchase.
What to put in the final acceptance schedule
Attach the accepted duty curve, model and impeller identification, connection drawing, agreed passage value, material schedule and supplied protection devices. Record which requirements remain conditional. A clean-water hydraulic test alone does not demonstrate the pump's behaviour with the actual site mixture; agree separately what evidence is required for solids and fibre handling.
Keep the wastewater description attached to the order. If the process later adds more fibres, grit or a different liquid, reassess the selection rather than relying on the old “non-clog” label.
Questions to resolve before sending the RFQ
Can I infer solids passage from WQ or WQP?
No. A family label is a starting point. The two catalog examples above show why the exact selected construction and its stated passage must be named separately.
Does a larger outlet settle the clogging question?
No. Ask for the pump passage and the bidder's response to your particles and fibres as well as the connection size.
Where should I start if the impeller type is still undecided?
Browse the sewage-pump records, use the full submersible sewage RFQ checklist for installation and electrical questions, and submit the wastewater description with your duty point through the structured RFQ. This note covers passage and connection dimensions; the broader checklist covers the rest of the installation.