A buyer searching for Mechanical Seal is usually trying to stop a bad substitute. A pump is specified at the duty point: flow, head, the liquid, and the power. The notes below are selection criteria for a Mechanical Seal. They are not a catalog promise. Confirm every rating on the current datasheet, drawing, or test report for the revision you will receive.
What has to be true of Mechanical Seal
A pump is specified at the duty point: flow, head, the liquid, and the power. For a Mechanical Seal, start from the duty, then the interface to the rest of the machine or the room, then the document that proves the claim. A lower price that leaves one of those blank is a different product.
Mechanical Seal is easy to confuse with Drum Pump. If the quote could be read as either, add the line that separates them: the rating, the fitment, or the standard named below. Link the drawing number to that line so receiving inspection can reject the wrong one.
Numbers that change the quote
| Line | What to write for Mechanical Seal |
|---|---|
| Seal | Mechanical seal or packing, and whether the liquid can leak. |
| Duty point | Flow and head together, not the maximum of each. |
| Liquid | What it is, the temperature, viscosity, and solids. |
| Materials | Casing, impeller, and seal matched to that liquid. |
| Power | Supply voltage and the power at the duty point. |
| Installation | Flooded, suction lift, or submersible depth. |
How to compare two offers
Lay both quotes for Mechanical Seal on one sheet and line up seal, duty point, and liquid. If a cell is empty, the offer is not finished. Ask for the missing line in writing. When those match, the honest difference is lead time, the test evidence, and who carries the warranty. Do not average a fully specified Mechanical Seal with a cheaper line that omitted seal.
Documents worth having before the deposit
Ask for the curve with the duty point marked. The file should name Mechanical Seal and the revision, not only the supplier’s homepage. A factory quality certificate such as ISO 9001 can sit beside that file. It does not replace it.
Failures that show up after delivery
- Ignoring NPSH when the suction is difficult.
- Sizing on maximum flow at zero head.
- Using a water pump on a solvent or a slurry.
On a Mechanical Seal, the expensive version of the first mistake is discovering it after the goods are in the crate. Put the rejection condition in the purchase order while the supplier can still restate the offer.
A worked RFQ line
Use this shape, then replace the brackets with your duty: “Mechanical Seal — Write flow, head, liquid, materials, and power.” That sentence is a template, not a rating of any brand. If a supplier’s datasheet uses different units, convert them onto this sheet so the next offer can be compared.
Where words like automotive grade belong
Searches often add a constraint to Mechanical Seal: automotive grade, or explosion-proof / ATEX. Keep those on this page. Automotive grade is a temperature, vibration, and documentation claim. Ask which AEC or customer spec is actually met, and for which part number. ATEX or IECEx is a certificate for a zone, a gas or dust group, and a temperature class. An IP rating does not grant it. Skip the mark if the site is not hazardous. If you need a third constraint, add it as another line on the same drawing. A second URL that only swaps the adjective does not give a buyer a second fact.
Related in this section: how to specify Drum Pump.
Questions buyers actually ask
What should an RFQ for Mechanical Seal include?
Write flow, head, liquid, materials, and power.
Is a cheaper Mechanical Seal the same part?
Only if seal, duty point, and the documents match. A missing line is a different offer.
Do waterproof, OEM, or IP words need their own page?
No. For Mechanical Seal they are extra lines on this specification. Ask for the test or the drawing that gives the word a value.