4″ Replacement Diaphragms for Pumps
Finding the right 4 inch replacement diaphragms can be tricky, since fewer pumps use this larger size.
The CH&E 4-inch diaphragm is a full set: P2157R for rubber, P2157N for neoprene, P2157B for Buna, and P2157T for TPE. Match the part number to the material your job needs.
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Ken’s Distributing stocks 4-inch diaphragms for the main brands that run them, in four materials, ready to ship the same day. This page shows what we carry, how to choose the right material, and how to confirm the fit before you order. A 4-inch diaphragm moves serious volume, so a worn one costs you real flow on big dewatering jobs. Once you know your pump model and material, the swap is quick.Shop 4-Inch Diaphragms by Pump Brand
The 4-inch size is built around a few heavy-duty pumps. Find your pump below, then choose your material. If your model is not listed, send it over and we will match it.| Pump Brand | 4-Inch Part Number / Models | Materials We Stock |
| CH&E | P2157R, P2157N, P2157B, P2157T | Rubber, Neoprene, Buna, TPE |
| Mud Hog | Fits 403, 404, 405, 414, 419, 445, 446 (part numbers by quote) | Rubber, Neoprene, Buna, TPE |
| Gorman-Rupp | 4″ | Neoprene, TPE |
Which Material Is Right for Your 4-Inch Pump?
The material decides how long your diaphragm lasts and what fluids it can handle. Here is a plain breakdown so you can pick with confidence.Rubber
Rubber is the budget pick for plain water and light-duty work. It flexes well and handles everyday dewatering. Many crews keep a few of our rubber replacement diaphragms on the truck as spares.Neoprene
Neoprene is the tough all-arounder, with strong tensile strength and good resistance to weather and flex cracking. On a hard-working 4-inch pump, it holds up to steady abuse. Browse our neoprene diaphragms to compare options.Buna (Nitrile)
Buna resists oils, fuels, and hydrocarbons. Pick it when you pump near diesel, lubricants, or petroleum fluids, since plain rubber breaks down fast around those.TPE (Santoprene)
TPE blends thermoplastic strength with rubber-like flex and broad chemical resistance. It is one of the longest-lasting choices for heavy industrial service. See the full lineup of TPE Santoprene diaphragms if uptime matters most.How to Measure a 4-Inch Diaphragm Before You Order
The “4-inch” refers to your pump’s port size, not the diaphragm itself. To get the right part the first time, check these four things:- Overall diameter, measured straight across the full diaphragm.
- Bolt-hole pattern: count the holes and measure the spacing center to center.
- Center mounting hole or stud opening diameter.
- Pump make and model, such as CH&E 4-inch, Mud Hog 414, or your Gorman-Rupp model.
Pumps We Fit
We supply 4-inch diaphragms for the main brands that use them, including CH&E, Mud Hog, and Gorman-Rupp. For CH&E and Magnum owners, our CH&E and Magnum diaphragms page lists the P2157 part numbers by material. Need a smaller size for another pump? See our 3-inch replacement diaphragms too. Do not see your brand? Reach out and we will cross-reference it.Why Buy From Ken’s Distributing
- America’s water pump parts distributor since 1991.
- Authorized dealer for Franklin Electric, Monarch, CH&E, Generac Magnum, Red Lion, Little Giant, AMT, and Wacker Neuson.
- Most orders ship the same day to all 50 states and Canada.
- Diaphragms built to hold up under heavy jobsite abuse.
- Real people who know pumps and can confirm your fit by phone.
Bulk Orders and Contractor Pricing
Run a fleet or several crews? Set up a blanket order for your 4-inch diaphragms and lock in contractor pricing with scheduled fulfillment. That way a big pump is never down waiting on a part. Ask our team about volume pricing when you request your quote.4-Inch Diaphragm Questions, Answered
How do I know if I need a 4-inch diaphragm?
The “4-inch” refers to your pump’s port or discharge size. Check the model plate or measure the discharge outlet. When in doubt, send us your make and model.Why are there fewer 4-inch options than 2-inch or 3-inch?
The 4-inch size is used on larger, higher-volume pumps, so fewer brands build them. CH&E, Mud Hog, and Gorman-Rupp are the main ones we stock.What is the CH&E 4-inch part number?
CH&E uses P2157, with a letter for the material: P2157R rubber, P2157N neoprene, P2157B Buna, and P2157T TPE.How fast can I get my part?
Most orders ship the same day, nationwide and to Canada.Can I order in bulk?
Yes. We offer blanket orders and contractor pricing for shops and multi-crew operations.Get a Quote on Your 4-Inch Diaphragm
Tell us your pump brand, model, and material, and we will get you the right part fast. Fill out the quick form with your name, email, phone, and pump details, and our team will reply with pricing and availability. Prefer to talk it through? Call (303) 699-7845 or email kendisco@yahoo.com and we will confirm your fit on the spot.
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