AODD Diaphragm Chemical Compatibility Chart
On an air-operated diaphragm pump, check every wetted material, not just the diaphragm: housing, diaphragm, check balls and seats. Below are FTI Air's published ratings for 49 common chemicals. One result matters more than most: the 3-inch FT30P's glass-filled polypropylene is rated not recommended for sodium hypochlorite, sulfuric acid from 70%, chromic, nitric and hydrofluoric acid — chemicals where plain polypropylene or PVDF often rate well.
Ratings by chemical
A excellent · B good · C fair · X not recommended · — no data. A number after the letter is FTI's maximum temperature in °F for that material. Ratings assume ambient temperature unless shown.
| Chemical | Glass-filled PP FT30P housing | Polypropylene smaller FTI housings, PP seats | PVDF housing / seats | Santoprene diaphragm, ball | EPDM diaphragm, ball | FKM diaphragm, ball | PTFE diaphragm, ball | Buna-N diaphragm, ball | Neoprene diaphragm, ball | Hytrel diaphragm | Polyurethane diaphragm | 316SS ball |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Acetic Acid, 10% | A | A | A | C | A | X | A | C | C | A | C | A |
| Aluminum Chloride, 20% | A | A | A | A | A | A | A | A | A | B | C | X |
| Aluminum Sulfate (28%) | A | A | A | A | A | A | A | A | A | A | B | B |
| Ammonium Hydroxide, 10% | A | A | A | A | A | C | A | A | B | X | X | B |
| Ammonium Sulfate | A | A | A | A | A | A | A | A | A | C | A | A |
| Calcium Hydroxide | A | A | A | A | A | A | A | A | A | C | C | A |
| Chlorine Dioxide, 15% | X | X | A | X | X | C | A | X | X | — | X | X |
| Chromic Acid, 10% | X | A | A | A | A | A | A | X | X | X | X | B |
| Citric Acid | A | A | A | A | A | A | A | A | A | A | A | A |
| Copper Sulfate | A | A | A | A | A | A | A | A | A | A | A | A |
| Ethylene Glycol | A | A | A | A | A | A | A | A | A | A | B | A |
| Ferric Chloride | A | A | A | A | A | A | A | A | A | X | A | — |
| Ferric Sulfate | A | A | A | A | A | A | A | A | A | C | C | A |
| Hydrochloric Acid, 10% | A | A | A | A | X | A | A | C | C | C | B | X |
| Hydrochloric Acid, 37% | A | A | A | A | X | B | A | X | X | X | X | X |
| Hydrofluoric Acid, 30% | X | A | A | X | C | A | A | X | C | X | X | X |
| Hydrofluoric Acid, 50% | X | A/150 | A | X | X | A | A | X | X | X | X | X |
| Hydrogen Peroxide, 5% | A | A | A | A | B | A | A | B | C | X | C | A |
| Hydrogen Peroxide, 30% | A | A | A | A | C | A | A | X | X | X | C | B |
| Nitric Acid, 10% | X | A | A | A | B | A | A | X | X | X | X | A |
| Nitric Acid, 70% | X | X | A | X | X | A | A | X | X | X | X | A |
| Peracetic Acid, 40% | X | X | C | C | B | A | A | — | B | X | — | B |
| Phosphoric Acid, 25% | A | A | A | A | A | A | A | B | B | — | C | A |
| Phosphoric Acid, 85% | A | A | A | C | A | A | A | X | C | X | X | A |
| Plating Solutions, Chrome | C | C | A | A | C | A | A | X | X | — | X | C |
| Plating Solutions, Copper | A | A | A | A/70 | A | A | A | A | C | — | X | X |
| Plating Solutions, Nickel | A | A | A | A/70 | C | A | A | X | C | — | A/150 | C |
| Plating Solutions, Zinc | A | A | A | — | C | A | A | A | C | — | A/150 | X |
| Potassium Hydroxide, 50% | A | A | X | A | A | A | A | B | B | X | C | A |
| Potassium Permanganate | A/70 | A/70 | X | A | A | A | A | X | C | — | B | B |
| Propylene Glycol | A | A | A | A | A | A | A | A | C | — | B | A |
| Sewage | A | A | A | A | C | A | A | A | B | B | X | A |
| Sodium Bisulfite | A | A | A | A | A | A | A | A | A | C | A | B |
| Sodium Carbonate | A | A | A | A | A | A | A | A | A | C | A | A |
| Sodium Hydroxide, 25% | A | A | X | A | A | X | A | A | B | X | C | A |
| Sodium Hydroxide, 50% | A | A | X | A | A | X | A | X | C | X | C | A |
| Sodium Hypochlorite, 5% | X | B/72 | A | A | A/122 | B | A | X | B | C | C | A |
| Sodium Hypochlorite, 12.5% | X | B/72 | A | A | A/122 | B | A | X | B | C | X | C |
| Sodium Silicate | A | A | A | A | A | A | A | A | A | A | B | A |
| Sulfuric Acid, 10% | A | A | A | A | A | A | A | X | X | A | C | B |
| Sulfuric Acid, 30% | A | A | A | A | A | A | A | X | X | A | C | X |
| Sulfuric Acid, 60% | A | A | A | B | A | A | A | X | X | X | X | X |
| Sulfuric Acid, 70% | X | A | A | B | A | A | A | X | X | X | X | X |
| Sulfuric Acid, 93% | X | C | A | C | B | A | A | X | X | X | X | X |
| Sulfuric Acid, 98% | X | X | B | C | X | A | A | X | X | X | X | B |
| Urea | A | A | A | A | A | A | A | A | B | B | C | A |
| Water, Deionized | A | A | A | A | A | A | A | A | C | A | A/70 | A |
| Water, Sea | A | A | A | A | A | A | A | A | C | C | C | A |
| Zinc Chloride | A | A | A | A | A | A | A | A | B | C | A | A |
Source: FTI Air AODD Chemical Resistance Guide (rev. April 6, 2026), selected rows. FTI notes the chart is a guide only and is not warranted as accurate or complete; temperature, concentration, mixtures and abrasion change the answer. LibertyCES confirms every wetted material for your fluid before quoting.
How to choose a diaphragm, ball and seat
- Housing first. If the housing is rated X, no diaphragm saves the pump. Note that glass-filled polypropylene and plain polypropylene rate differently.
- Then the diaphragm. Pick the best-rated elastomer for the chemical at its concentration and highest temperature.
- Check balls and seats separately. They see the same fluid plus the wear of every stroke. On the FT30P, seats come in polypropylene or PVDF and balls in the elastomers, PTFE or 316 stainless.
- Mind the temperature. Each material has a mechanical limit too (FT30P housing: 32–158°F). The lower of the chemical and mechanical limits governs.
- Abrasives change the pick. A chemically excellent PTFE diaphragm can wear fast in a gritty slurry where Santoprene or polyurethane lasts.
Elastomer background: Buna-N vs EPDM vs FKM vs PTFE · Non-AODD equipment: LibertyCES chemical compatibility chart
Flammable fluids and solvents
Chemical resistance is not the only rule. FTI Air warns never to use a polypropylene or PVDF pump with flammable or combustible fluids; its guide marks alcohols, acetone and similar fluids as requiring the conductive polypropylene version. Halogenated hydrocarbon solvents can cause an explosion when run through pumps with aluminum components in a closed, pressurized system. These hazards override any letter rating.
Size it right before you buy
Enter flow, head, SG and plant air. See the air pressure and SCFM your duty needs on a real FTI Air FT30P curve, then get the worksheet by email.
The Finish Thompson MSDB pump-review checklist: carbon-bushing run-dry limits, NPSH margin and the suction-piping rules that decide pump life.
Diaphragm material questions
Which diaphragm material is best for acids?
For hydrochloric acid, FTI Air rates Santoprene and PTFE excellent up to 37%, FKM excellent to 20% and good at 37%, and EPDM not recommended. For sulfuric acid up to 60%, EPDM, FKM and PTFE are rated excellent and Santoprene excellent to 33% and good above; for 93–98% sulfuric only FKM and PTFE stay excellent. Stronger nitric and hydrofluoric acid narrow it to FKM and PTFE.
Which diaphragm material is best for caustic (sodium hydroxide)?
For sodium hydroxide up to 50%, FTI Air rates EPDM, Santoprene and PTFE excellent and FKM not recommended. PVDF housings are also rated not recommended for sodium hydroxide, so caustic AODDs use a polypropylene body.
Can a polypropylene diaphragm pump handle sodium hypochlorite?
It depends on the polypropylene. FTI Air rates plain polypropylene good for 5% and 12.5% sodium hypochlorite only up to 72°F, and glass-filled polypropylene — the housing of the 3-inch FT30P — not recommended. PVDF is rated excellent, with EPDM, Santoprene or PTFE elastomers.
Is glass-filled polypropylene different from polypropylene for chemical resistance?
Yes. The glass fibers can be attacked by some chemicals that plain polypropylene tolerates. In FTI Air's guide, glass-filled polypropylene is rated not recommended for sodium hypochlorite, sulfuric acid from 70%, chromic acid, nitric acid and hydrofluoric acid, where plain polypropylene is often rated good or excellent.
Can I pump solvents or fuels with a plastic diaphragm pump?
Not with a standard plastic pump. FTI Air warns never to use a polypropylene or PVDF pump with flammable or combustible fluids, and its guide requires the conductive polypropylene version for alcohols, acetone and similar fluids. Halogenated hydrocarbon solvents must never be run through pumps with aluminum parts in a closed system.
Not sure which materials fit your chemical?
Send the chemical, concentration, temperature and any solids. James confirms the housing, diaphragm, ball and seat against the manufacturer's data and sizes the pump — no charge.
FT30P 3-inch diaphragm pump · AODD pumps · Browse all guides & downloads