2″ CH&E Replacement Diaphragm – TPE

The CH&E 2 Inch TPE Replacement Diaphragm P2331TPE is the thermoplastic version of the 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 6400 cast iron build. TPE is one of five compounds CH&E lists for this part, alongside rubber, neoprene, Buna-N and Viton. Your pump uses one. Check your model and serial number before ordering. Ken’s Distributing can help you match the compound to your job.

Product Highlights

• Part number P2331TPE. Listed in US government stock records under NSN 4320-00-888-9001.
• Base part number P2331, item 15 in the CH&E 2 inch parts list.
• Fits CH&E 5400 series aluminum and 6400 series cast iron 2 inch pumps.
• TPE is one of five compounds CH&E lists. Viton is also available as P2331V.
• One diaphragm per pump.
• CH&E does not make a TPE flap valve. Ask us about the rest of the wetted path.
• Matching TPE rebuild kit is W103-020.0T.

Specification Table

Listing the temperature and chemical rows as not published is deliberate. A blank row looks like an oversight. A row that says the manufacturer does not publish it, and invites the buyer to call, is a trust signal and a lead.

About the CH&E 2 Inch TPE 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. The TPE version is P2331TPE. Your pump uses one.

TPE stands for thermoplastic elastomer. It is one of five compounds CH&E lists for this part.

The five compounds, and where TPE sits

All five share the same shape and the same mounting. Switching compound does not change how the part fits or what torque you use.

Note that TPE uses a three letter ending, not a single letter like the others. If you search for P2331T you will not find it.

What we can and cannot tell you about TPE

We can tell you what the part is. P2331TPE appears in US government stock records under National Stock Number 4320-00-888-9001, together with the base number P2331. That is a documented part number, not a catalogue guess.

We cannot give you a temperature rating, a chemical compatibility list, or a service life figure. CH&E does not publish them. Because the reviewed CH&E documentation does not provide a temperature range, chemical-compatibility chart or service-life figure, avoid relying on unsupported performance claims.

So do not choose a compound from a web page. Tell us what you pump, how hot it gets, and what failed last time. We will help you pick, and we will say so if we are not sure.

If your fluid is genuinely aggressive, ask us about Viton, part P2331V. It sits above TPE in the CH&E range and it is often the right answer for chemical service.

Do not forget the flap valve

This matters and almost nobody mentions it.

The flap valve sits in the same fluid stream as the diaphragm. CH&E does not make a TPE flap valve. For the 2 inch pump the options are:

• SA-10003B, Buna-N
• SA-10003N, neoprene, shown as standard fitment in the parts list
• SA-10003V, Viton
• SA-10004N, neoprene with a cloth insert

So if you are choosing TPE because of what you are pumping, your flap valve will be a different compound. Think about the whole wetted path, not just the diaphragm. Call us and we will go through it with you.

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 number for both. They differ in the metal used for the wetted parts, not in the diaphragm. Model numbers include 5401, 5402, 5403, 5405, 6401, 6402, 6403 and 6405.

CH&E built other 2 inch diaphragm pumps outside these series. We have not confirmed this part for those. If your model does not start with 54 or 64, contact us first.

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. The torque is the same whichever compound you fit.

Parts to check while the pump is open

• Flap valve assembly, from the list above
• Diaphragm bottom plate, P3353
• Retaining washers, P3360, two per pump
• Connecting rod, P3352

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

Talk to us about your conditions

Send us your pump model number, your serial number, what you are pumping, and how the last diaphragm failed. Ken’s Distributing will help you choose the compound and the matching flap valve.

Frequently Asked Questions

What pumps does part number P2331TPE fit?

P2331TPE is the TPE version of the diaphragm listed in the CH&E parts manual for 2 inch gas engine powered pumps in the 5400 aluminum series and the 6400 cast iron series. One base number, P2331, covers 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 before you order.

Why is the TPE part number written differently from the others?

TPE uses three letters at the end instead of one. The other compounds use a single letter, so you see P2331R for rubber, P2331N for neoprene, P2331B for Buna-N and P2331V for Viton. The TPE version is written P2331TPE. This trips people up when searching or phoning an order through. If you look for P2331T you will not find the part. Use the full three letters.

Is TPE the toughest compound CH&E lists?

No. CH&E lists five compounds, and Viton sits above TPE for aggressive chemical service. The five are rubber, neoprene, Buna-N, TPE and Viton. You will see TPE described as the top option on many websites, including ours until recently, but that compares only three of the five. If your fluid is genuinely harsh, ask us about Viton, part number P2331V, before you settle on TPE.

What flap valve should I use with a TPE diaphragm?

There is no TPE flap valve. CH&E lists four flap valve assemblies for the 2″ pump and none of them is TPE. The options are SA-10003B in Buna-N, SA-10003N in neoprene, SA10003V in Viton, and SA-10004N in neoprene with a cloth insert. The parts list shows SA10003N as standard fitment. The flap valve sits in the same fluid as the diaphragm, so call us and we will help you pick one.

Does TPE last longer than rubber or neoprene?

We cannot tell you that, and neither can anyone else honestly. CH&E does not publish service life figures, temperature ratings or chemical compatibility data for any of its diaphragm compounds. We have looked. Any seller giving you a hard number is guessing. What we can do is help you reason it through. Tell us what you pump, how hot the job runs, and how your last diaphragm failed, and we will give you our best view.

Is P2331TPE the same as P2231TPE?

No. P2331TPE is the number that appears in US government stock records alongside the base number P2331. P2231TPE 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 P2231TPE, do not assume it is the same part. Send us the number with your pump model and we will check it before you buy.

Can I switch from rubber or neoprene to TPE without changing anything else?

Yes, as far as fitting goes. All five compounds share the same shape and the same mounting, and the torque setting does not change. So a TPE diaphragm goes into the pump exactly like a rubber or neoprene one. What we cannot promise is a performance difference, because no compound data is published. If you are switching because something failed, tell us how it failed. That is more useful than the compound name on its own.

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. The 3 inch pumps use a higher setting, so check your pump size.