Identify the Exact STX Pump and Impeller
Start with the installed pump size and the existing impeller information. STX identifies a frame family, but the required replacement still depends on the exact pump size, impeller reference, trim diameter, material and installed wet-end configuration.
- Pump size
- STX frame
- Impeller reference and part number
- Trim diameter
- Material
- Photographs of the removed impeller and nameplate
- Drawing or parts list, if available
If the part reference is uncertain, use an OEM part-number cross-reference before machining or casting.
Why Impeller Trim Diameter Matters
The same impeller casting or hydraulic family may be supplied at different finished diameters. The required trim must therefore be confirmed from the installed pump documentation or the applicable performance curve. Do not assume that frame identification alone determines the final impeller diameter.
Impeller diameter affects the available head, flow and power relationship. For an existing pump that is producing excess head, review the impeller-trimming guide before treating a diameter change as a simple part substitution.
Verify Material Before Ordering
Confirm the existing material from the parts list, specification, MTR or another reliable record. Visual appearance is not sufficient for alloy identification. If a material change is being considered, review the process liquid and operating temperature before selecting the replacement material.
CF8M, CD4MCuN and Hastelloy C-276 may be relevant in different services, but availability and suitability must be confirmed for the exact STX impeller, casting specification and process conditions. Concentration, temperature, contaminants, solids and the observed failure mode all matter.
Inspection Before Shipment
Define the inspection scope in the RFQ and retain the records with the pump asset. Depending on the project, the review may include:
- Visual inspection of casting and finished surfaces
- Dimensional inspection of the hub, bore, keyway, vane profile and finished diameter
- Material traceability and MTR review
- PMI when specified and offered for the order
- Dynamic balance when specified and offered for the order
- Runout and clearance checks against the applicable drawing
Do not add a tolerance or balance grade unless it is supported by the applicable drawing, project specification or agreed inspection plan.
Configuration and Fit Checks
| Check | Why it matters | Evidence |
|---|---|---|
| Pump size and STX frame | Narrows the applicable impeller configuration | Nameplate and model record |
| Impeller reference | Distinguishes similar family parts | Parts list, drawing or removed-part photograph |
| Trim diameter | Controls the expected hydraulic curve | Curve, drawing or measured component |
| Shaft interface | Confirms mechanical fit | Drawing, shaft and keyway information |
| Mating wet end | Confirms clearances and hydraulic relationship | Casing, wear-ring and seal-area details |
What to Send for an Impeller Quote
- Pump model and exact size
- STX frame
- Impeller part number or reference
- Required trim diameter
- Material and process conditions
- Quantity
- Existing impeller and nameplate photographs
- Drawing or parts list
- Required MTR and inspection documents
- Required delivery date
Availability and delivery depend on the exact material, size, casting status, machining scope, inspection requirements, quantity and current inventory. Confirm these points during quotation.
Request a Dimension and Material Review
Send the installed pump data, impeller reference, trim diameter, material record and photographs so the replacement can be reviewed against the actual configuration. See the Goulds 3196 replacement parts resource for related platform information.
Request an STX impeller fit review
Frequently Asked Questions
Does STX frame identification determine the correct impeller?
No. Confirm the exact pump size, impeller reference, trim diameter, material and mating wet-end configuration.
Can I identify impeller material by appearance?
No. Use the parts list, specification, MTR or another reliable material record. PMI may be appropriate when included in the agreed inspection scope.
Can the trim diameter be selected from the frame alone?
No. Confirm it from the installed documentation or applicable performance curve, then verify the final diameter against the pump and system duty.
What should be inspected before shipment?
Define the order scope. Typical checks may include visual, dimensional, material traceability, PMI, balance and runout review when specified and available.
