2″ CH&E Replacement Diaphragm – Rubber

The CH&E 2 Inch Rubber Replacement Diaphragm P2331R is a diaphragm for CH&E 5400 and 6400 series pumps. The CH&E parts manual lists P2331 as item 15 for both the 5400 aluminum and the 6400 cast iron build. Your pump uses one. CH&E documentation associates the P2331 diaphragm reference with multiple material options, including rubber, neoprene, Buna-N, TPE and Viton. Confirm the material previously installed and the requirements of the pumping application before requesting a quote. Ken’s Distributing can help you confirm fitment.

Product Highlights

• Manufacturer part number P2331, item 15 in the CH&E 2″ parts list. Rubber variant P2331R.
• Fits CH&E 5400 series aluminum and 6400 series cast iron 2 inch pumps.
• Rubber compound. The same base part is also listed in neoprene, Buna-N, TPE and Viton.
• One diaphragm per pump.
• Matching rubber rebuild kit is W103-020.0R.
• The reviewed CH&E parts list does not show a rubber flap-valve option for the covered 2-inch pump configurations.
• Check your pump model and serial number before ordering.

Specification Table

About the CH&E 2 Inch Rubber Replacement Diaphragm

This is the flexing part that drives water through the pump. It sits between the pump frame and the water box. When it splits or leaks, the pump stops priming, loses stroke, or stops moving water.

The CH&E parts manual lists this part as item 15, number P2331, for 2″ gas engine powered pumps. Your pump uses one.

Rubber is one of five compounds this part comes in. All five share the same base number.

The shape is the same across all five. Only the compound changes. That means switching compound does not change how the part mounts.

Which compound should you pick

Rubber is described as the standard compound on CH&E diaphragm pumps, with neoprene, Buna-N and Viton offered as replacements. That comes from a distributor catalogue for the CH&E pump line, not from the pump manual, so treat it as a guide rather than a specification.

We do not publish wear or chemical ratings for these compounds, because CH&E does not publish them either. Anyone who gives you a hard number for how long a compound lasts is guessing.

What we can do is help you match the compound to your job. Tell us what you pump, how often the pump runs, and what compound was in the pump before. Call us and we will talk it through.

Which pumps this diaphragm fits

The CH&E manual lists P2331 for these 2 inch gas engine powered pumps:

• CH&E 5400 series, aluminum
• CH&E 6400 series, cast iron

The manual uses the same part number for both. The two differ in the metal used for the wetted parts, not in the diaphragm.

Model numbers in these series include 5401, 5402, 5403, 5405, 6401, 6402, 6403 and 6405. Confirm your exact model.

CH&E built other 2 inch diaphragm pumps outside the 5400 and 6400 series. We have not confirmed that this part fits those. If your model number does not start with 54 or 64, contact us before you order.

How to confirm this fits your pump

1. Find the nameplate on your pump. Write down the model number and the serial number. The CH&E manual asks you to record both before ordering any part.
2. Check the port size. The 2 inch is where the hose connects, not the width of the diaphragm.
3. Pull your old diaphragm. Measure the outside diameter and the thickness, and count the holes.
4. Look for a number stamped on the old part and compare it to P2331.

If any step does not line up, stop and contact us. Do not order by how the part looks.

Fitting the diaphragm

The CH&E manual gives these steps for 2 inch pumps.

Turn the connecting rod to the down position. Take out the four bolts that clamp the diaphragm between the pump frame and the water box. Take off the three nuts holding the diaphragm to the diaphragm bottom plate.

Fit the new diaphragm onto the studs and the bottom plate. Use a pipe spacer over the studs to seat it. Put the assembly back on the connecting rod.

Tighten the three nuts to 34 to 40 N-m, which is 25 to 30 lb-ft. Center the diaphragm over the water box. Clamp it with the four bolts in a crossing pattern at the same torque.

Parts to check while the pump is open

• Flap valve assembly. Note that CH&E does not list a rubber flap valve for this pump. The listed options are Buna-N SA-10003B, neoprene SA-10003N, Viton SA-10003V, and SA-10004N which is neoprene with a cloth insert. The parts list shows SA10003N as the standard fitment
• Diaphragm bottom plate, P3353
• Retaining washers, P3360, two per pump
• Connecting rod, P3352

If more than one is worn, the rubber rebuild kit W103-020.0R may cost less than buying parts one at a time.

Need help with fitment

Send us your pump model number, your serial number, and any number stamped on your old diaphragm. Ken’s Distributing will check it against the CH&E parts list and tell you what you need.

Frequently Asked Questions

What pumps does part number P2331 fit?

P2331 is listed in the CH&E parts manual as the diaphragm for 2″ gas engine powered pumps in the 5400 aluminum series and the 6400 cast iron series. The manual uses one number for both builds. Model numbers include 5401, 5402, 5403, 5405, 6401, 6402, 6403 and 6405. CH&E built other 2 inch pumps outside these series, and we have not confirmed this part for those. Check your nameplate, and contact us if your model does not start with 54 or 64.

What does the R mean in P2331R?

The letter at the end shows the compound. R means rubber. CH&E uses one base number with different letters for each material. You will see N for neoprene, B for Buna-N, V for Viton and TPE for the TPE version. Older paperwork may show P2331 with no letter at all. Every version shares the same shape and mounting, so the letter tells you the compound and nothing else. Ask us if your paperwork does not show a letter.

Is P2331 the same as P2231?

No. P2331 is the number printed in the CH&E parts manual for the 2 inch diaphragm. P2231 is a different string of digits. You may see it on parts lists or older paperwork, including some pages on this site that we are correcting. If your paperwork shows P2231, do not assume it is the same part. Send us the number along with your pump model and we will check it against the CH&E parts list before you buy.

Does the rubber version fit the same as the neoprene version?

Yes. All five compounds share the base number P2331 and the same shape. The mounting is identical, so a rubber diaphragm and a neoprene diaphragm go into the pump the same way and use the same torque. Only the compound differs. That means you can switch compound at your next service without changing anything else on the pump. If you are unsure which compound is in your pump now, send us a photo of the old part.

Is there a rubber flap valve for this pump?

No. The CH&E manual lists four flap valve assemblies for the 2 inch pump and none of them is rubber. The options are SA-10003B in Buna-N, SA-10003N in neoprene, SA-10003V in Viton, and SA-10004N which is neoprene with a cloth insert. The parts list shows SA10003N as the standard fitment. The reviewed parts list shows SA-10003N neoprene as the standard flap-valve listing. Confirm the valve material currently installed before ordering replacements.

Which compound should I choose for my pump?

It depends on what you pump and how hard the pump works. We do not publish wear ratings or chemical limits for these compounds, because CH&E does not publish them. A distributor catalogue describes rubber as the standard compound on this pump line, with neoprene, Buna-N and Viton offered as replacements. The best guide is what was in your pump before and how it wore. Call us with your job details and we will help you choose.

What torque should I use when I fit this diaphragm?

The CH&E manual gives 34 to 40 N-m for 2 inch pumps, which is 25 to 30 lb-ft. Use it twice. First on the three nuts holding the diaphragm to the diaphragm bottom plate. Then on the four bolts clamping the diaphragm between the pump frame and the water box. Tighten those four in a crossing pattern so the clamp is even. Uneven clamping can make a diaphragm leak or tear early, whatever compound it is.

Which other parts should I check while the pump is open?

Check the flap valve assembly first, since there is no rubber version and yours may be a different compound. Then look at the diaphragm bottom plate P3353, the two retaining washers P3360, and the connecting rod P3352. These sit next to the diaphragm and wear at a similar rate. If more than one is worn, the rubber rebuild kit W103-020.0R may cost less than single parts. Ask us and we will tell you which suits your pump.