These figures provide simplified information for searching, filtering and initial comparison. They are not a complete specification. Exact details depend on the model and configuration.
Power rating: Usually the motor’s rated mechanical output (P2). Electrical input power (P1) is a different value. Check the product’s nameplate or manufacturer’s documentation to confirm which rating applies.
Outlet size: The nominal size class is expressed on a millimetre basis: for example, DN40 denotes a nominal 40 mm size. It does not specify the exact measured opening, connection type, thread, flange drilling or pressure rating.
Head and flow: Indicative figures describing the pump’s performance envelope, rather than a single operating duty point. Do not assume maximum flow is available at maximum head, or that every combination within the ranges is achievable. Minimum figures do not establish safe continuous operating limits. Consult the relevant performance curve.
Check the product description, nameplate and manufacturer’s documentation before selection or installation. Please contact us before purchasing if you need help confirming suitability or connection details.
| Shipping Weight | 0.5 kg |
| Package Dimensions | 20.0 × 20.0 × 10.0 cm |
Genuine Grundfos EPDM pump casing O-ring, part number 97757659. This replacement seal is used between the pump cover and pump casing on compatible Grundfos pumps, including selected NB, NK, TP and TPD models and their associated variants.
The O-ring provides a static seal at the casing joint. Grundfos identifies this sealing position as 72a in the applicable service documentation. The mechanical shaft seal is a separate component with its own replacement part number.
Grundfos’s current product record specifies EPDM and a dimensional designation of 171.04 × 3.53mm. Compatibility should be established using the exact spare-part number and the pump’s eight-digit product number. A researched list of manufacturer references is included below.
| Manufacturer | Grundfos |
| Product | Pump casing / pump cover O-ring |
| Grundfos part number | 97757659 |
| Manufacturer description | Spare, O-ring |
| Material | EPDM elastomer |
| Current catalogue dimensions | 171.04 × 3.53mm |
| Sealing function | Static seal between the pump cover and casing |
| Service drawing position | 72a in the applicable manufacturer documentation |
| Supply | Individual replacement O-ring |
| EAN | 5710623847986 |
| Our stock reference | #5041 |
Need help checking compatibility? Send us a clear photograph of the pump nameplate and existing part label. Call 01803 220416 or email kirk@thepumpdealer.co.uk.
Check that 97757659 is specified for your pump’s exact product number and sealing position. Grundfos uses different casing sizes, O-ring materials and constructions within the same pump family. A designation such as NB 65, TP 80 or TPD 100 is not sufficient on its own.
Confirmed references include selected NB, NBE, NBG, NBGE, NBS, NBSE, NK, NKE, NKG, NKGE, TP, TPD, TPE, TPED, TPE2 and TPE3 products. Coverage applies to the individual product numbers identified below, rather than every pump in those ranges.
It seals the joint between the pump casing and the cover or corresponding motor-stool assembly. The parts remain stationary relative to each other during operation. The applicable service drawing identifies this O-ring as position 72a.
No. The mechanical shaft seal seals around the rotating shaft. This O-ring seals the casing joint. A pump repair may require either component or both, depending on where the leak originates.
EPDM stands for ethylene propylene diene monomer, a synthetic rubber commonly used in water and hot-water sealing applications. Suitability also depends on the actual liquid, additives and temperature.
The current Grundfos product record and NB / NBE Range 6 service catalogue specify 171.04 × 3.53mm. Use the exact Grundfos part number when ordering, rather than selecting a replacement solely by measuring a used ring.
Some older Grundfos spare-parts publications describe 97757659 as 177.39 × 3.53mm. The current manufacturer record gives 171.04 × 3.53mm. We have used the current specification here. Where older paperwork differs, confirm the part number against the current pump service record and the replacement item’s label.
Grundfos’s NB / NBG service instructions call for replacement of gaskets and O-rings when servicing. A used ring may have taken a compression set or become damaged during removal, even if it initially appears intact.
Clean and inspect the seating surfaces, fit the correct ring without twisting or trapping it, and follow the pump-specific assembly instructions. Use the specified lubricant and fastener torques. The cited NB / NBG instructions specify soapy water for position 72a and cross-tightening of the casing nuts.
EPDM has poor resistance to mineral oil, which can cause swelling. Use the lubricant specified by Grundfos for the relevant pump and seal material.
A loose O-ring does not establish the operating rating of the complete pump. The permitted duty depends on the pump construction, sealing arrangement, liquid and temperature. Follow the pump nameplate and applicable Grundfos operating limits.
Those codes identify the mechanical shaft-seal arrangement and materials. The casing O-ring is a separate spare part. Different shaft-seal versions can specify the same casing O-ring, which is why the exact product-number references are useful.
No. A material name alone does not establish an approval for a particular component or installation. Grundfos’s NB / NBE catalogue distinguishes standard EPDM from specific EPDM-NSF replacement parts. Check the approval requirements and specified part for your pump.
This part number identifies an individual spare O-ring. Check the twin pump’s exploded drawing and the number of sealing joints being opened; servicing both heads may require more than one ring.
It addresses the casing joint when that joint and its O-ring are the source of leakage. Leaks from a shaft seal, plug, flange connection or damaged casting require the corresponding repair.
Quote 97757659 for this O-ring and #5041 for our stock reference. The eight-digit numbers at the ends of the compatibility entries below identify the pumps.
The Pump Dealer supplies new and unused surplus pumps and replacement parts. Packaging may show storage or handling marks. This item includes our 2-year guarantee. Please retain your purchase details and quote #5041 when contacting us.
We searched Grundfos Product Center and checked the manufacturer’s recommended-parts records. All 570 references below list O-ring 97757659. The list contains 562 detailed model designations, four published short model names and four service-special records for which a detailed model name was not published.
Each entry ends with the pump’s eight-digit Grundfos product number. Identical model descriptions with different product numbers are retained separately. Manufacturer model codes and suffixes have been preserved where published.
Grundfos publishes abbreviated model names for these four products. Their separately recorded shaft-seal codes are shown in brackets; these have not been used to invent a longer model designation. Each product’s recommended-parts record lists O-ring 97757659.
These manufacturer records explicitly list 97757659, but do not publish a detailed model name. They are included for identification by exact product number.
Compatibility reference: Grundfos Product Center product descriptions, technical data and recommended-parts records checked on 20 October 2026. The eight-digit numbers at the ends of the compatibility entries identify pumps. The replacement O-ring offered in this listing is 97757659. View the manufacturer’s O-ring record .
Specification & guidance notice: Technical information and FAQ content are provided in good faith based on manufacturer literature and industry experience. Descriptions of hydraulic types and application suitability represent general guidance only and do not constitute a guarantee of performance. Actual results will depend on system design, pipework losses, media characteristics, and installation conditions. Please consult the manufacturer & thier documentation and satisfy yourself that the equipment is suitable for your specific application prior to purchase.