What a Durco Mark III Cross-Reference Can Confirm
A part-number cross-reference can help identify a listed replacement candidate for a stated pump configuration. It does not, by itself, confirm that the part fits every Durco Mark III pump or is suitable for the installed service. Before ordering, keep the pump identity, exact part reference, material and relevant interfaces together.
Use the result as a starting point
Match the candidate against the installed pump’s full model and size, Group or frame, design variation, component function and available drawing. If one of those details is unknown, record it as an open verification item.
If you already have an OEM part number, begin with the OEM part-number cross-reference. The live lookup lists references for specific configurations and states that final fit is reviewed against the model, size or frame, material and configuration.
Identify the Installed Pump Before Comparing Part Numbers
Record the complete nameplate designation rather than copying only the family name or one character from the model. In its Mark 3 High Silicon Iron user-instruction nomenclature example, Flowserve uses the leading frame number to identify Group 1, 2 or 3; the other fields identify the power end, nominal suction and discharge sizes, pump modifier, nominal maximum impeller diameter, design variation, actual impeller size and impeller style. Treat this as the manual’s example, then confirm the installed Mark 3 variant against its own nameplate, parts list and current drawing. A “2” on its own is not a complete pump identity.
Design revisions can matter. In that same manual’s nomenclature example, the “A” design variation denotes a redesign for which the impeller and casing are no longer interchangeable with the earlier version. Confirm that this note applies to the installed Mark 3 variant, and check its applicable nameplate, drawing and revision records before treating two similar size strings as the same configuration.
A POS code identifies a component position; it is not an OEM part number or a universal fitment approval. Use the Durco Mark III POS code finder when the component function is known but the exact reference is not.
Check What the Cross-Reference Actually Matches
Keep the original OEM number, the replacement reference and the pump configuration in separate fields. A supplier’s replacement code, a POS identifier and a Flowserve item number may describe different things. Do not infer a one-to-one conversion between numbering systems unless the applicable parts documentation confirms it.
From part reference to an RFQ decision
Each step adds evidence. A search result alone does not complete the fitment review.
Record the installed unit
Capture the full model, Group, size and available nameplate or drawing details.
Use the right identifier
Search by OEM reference, or use POS to identify the component function.
Retain the configuration
Check size, design variation, material and the interfaces relevant to that component.
Resolve open evidence
Use the applicable drawing, parts list, IOM or engineering review for unresolved details.
Carry evidence into RFQ
Send the reference and pump context together so the quotation can be checked against them.
If the identified unit is a Durco Mark III Group 2 configuration, use the group-specific guide for its replacement scope. Do not apply a Group 2 listing to another group based only on a similar part name.
Separate Physical Fit from Service Suitability
For an individual part, verify the interfaces that determine assembly fit and the features that affect operation. The exact checks depend on the component and installed configuration; use the approved drawing, parts documentation and applicable manufacturer instructions rather than a generic tolerance or “universal” checklist.
For a POS 103 request, use the dedicated reverse-vane impeller fitment guide. Impeller type, trim and rear-cover relationship require configuration-specific review. Do not copy a clearance value or adjustment procedure from another model or manual revision.
If the replacement changes the impeller, speed or duty, review the curve for the exact proposed configuration through the pump performance-curves resource. A part-number match does not establish hydraulic performance.
ANSI dimensional context is not an internal-part cross-reference
ASME states that pumps of the same B73.1 standard dimension designation from all sources are intended to be interchangeable with respect to mounting dimensions, suction and discharge nozzle size and location, input shafts, baseplates and foundation bolt holes. This dimensional scope does not establish that internal parts, materials or hydraulic performance are interchangeable across pump families or revisions. See the B73.1 interchangeability and component-compatibility guide for that distinction.
What to Include in a Durco Mark III Parts RFQ
Send the information already available and identify anything that still needs confirmation. A useful request lets the supplier review one defined part against one defined installed configuration.
For a broader supply review covering an individual component, wet end or complete pump, continue to the Durco Mark III replacement resource. Confirm the exact supply scope and fitment evidence before quotation release.
Durco Mark III Cross-Reference FAQ
Does an OEM part-number match guarantee fit?
No. It identifies a listed candidate in its stated context. Confirm the installed model, Group, size, design variation, material and relevant interfaces before release.
What does a POS number tell me?
A POS number identifies a component position or function in the applicable parts reference. It does not, by itself, identify every configuration or approve a replacement.
What if I only have a pump nameplate or photo?
Send a clear, complete image and any available drawing or removed-part photos. The full designation and configuration can help identify which reference and fitment details still need confirmation.
Does ASME B73.1 make internal parts universally interchangeable?
No. The standard’s dimensional requirements do not establish universal interchangeability of internal parts across pump families, configurations or revisions.
Can I use the same impeller clearance value for every Mark III pump?
No. Use the applicable Flowserve IOM for the exact pump configuration, impeller arrangement and revision. This guide does not set or substitute a clearance value.
