A diaphragm valve seals flow with a flexible diaphragm pressed against a weir or a saddle, so the working parts never touch the process fluid. That makes it the standard choice for slurries, aggressive chemicals and contamination-sensitive service.
Chemical plants, pharmaceutical facilities, water treatment and mining all use diaphragm valves where a seat would foul. Lined and plastic bodies are common, and the bodies are the expensive part.
We buy diaphragm valves in any quantity — single items, mixed pallets or whole cribs, including valves that need repair and assemblies that are missing parts. We do not require a clean inventory before reviewing a list.
| Common patterns | Weir pattern and straight-through, Rubber, PTFE and EPDM diaphragms, Lined cast iron and lined steel bodies, PVC, CPVC, PP and PVDF bodies |
|---|---|
| Typical service | Aggressive chemical service, Pharmaceutical, Water treatment |
| What we look at | Body material and lining, pattern, size, diaphragm material and operator. We ask whether the lining is intact, because a lined body with a damaged lining is a re-line candidate rather than a spare. |
| What to keep | Keep the body and bonnet together and keep the compressor. Diaphragms perish in storage, so an old diaphragm tells us nothing about the valve. The body lining is the value. |
Patterns and variants
What turns up most often
Variants matter because they change the buyer pool. A standard pattern sells to a rebuilder or a plant with the same service; a specialised trim sells to a much smaller group but often at a higher price. If you are unsure which variant you have, the nameplate or the trim marking will usually say.
Before it leaves site
How to protect the value
Keep the body and bonnet together and keep the compressor. Diaphragms perish in storage, so an old diaphragm tells us nothing about the valve. The body lining is the value.
Where they come from
Industries and services
- Aggressive chemical service
- Pharmaceutical
- Water treatment
Most of the surplus we see comes from plants that have replaced equipment for a reason that has nothing to do with the valve: a unit was re-rated, a line was re-piped, a control loop was upgraded or a project was re-scoped. The valve is simply the part that has to move.
Related patterns
Other valve types
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Read →Questions sellers ask
Do you buy valves with perished diaphragms?
Yes. Diaphragms are consumables and are replaced as part of recommissioning. The body, lining and bonnet are what we are buying.
Are plastic-bodied diaphragm valves saleable?
In quantity and in good condition, yes. PVDF and PP bodies hold value better than PVC.
What about lined bodies with lining damage?
Tell us where and how bad. Some damage is repairable and some is not, and we price accordingly rather than guessing.