Guide
Compressor valve plate materials: PEEK, PTFE or metal?
The sealing elements – valve plates, rings, poppets and damper washers – are the moving parts of a compressor valve and decide how long it lasts. This guide explains when PEEK, PTFE or metal is the right choice, and why changing the material usually means recalculating the valve.
Which parts are we talking about?
Every self-acting compressor valve has moving sealing elements that open and close with each revolution – depending on the design, these are plates, rings or poppets.
- Valve plates – one slotted plate seals several concentric seat ports (plate valves).
- Valve rings – individual sealing rings, each with its own springs (ring valves).
- Poppets – many small individual sealing elements in one seat (poppet valves).
- Damper plates and washers – sit between the sealing element and the guard and cushion the impact when the valve opens.
We supply all of these in PEEK, PTFE or metal, depending on the part and the application – to our own design, to your drawing or from a sample.
PEEK, PTFE and metal compared
There is no best material for every compressor: metal handles the highest temperatures and pressure differences, PEEK tolerates impact, dirt and liquid best, PTFE offers the widest chemical resistance at moderate loads.
| Property | Metal (hardened steel) | PEEK (unfilled or fibre-reinforced) | PTFE (filled) |
|---|---|---|---|
| Temperature | highest | high | moderate |
| Pressure difference | highest | high, depending on thickness and support | low to moderate |
| Impact tolerance | low – often combined with damper plates | high | moderate |
| Tolerance of dirt and liquid | low | high | moderate |
| Wear on the seat | higher | low | low |
| Chemical resistance | depends on steel grade | very good for most process gases | excellent |
| Moving mass | high | low | low |
| Typical use | high pressure, high temperature, clean gas | process and natural gas compressors, wet or dirty gas | aggressive media at moderate pressure |
The table shows tendencies. Where a material actually reaches its limit depends on the valve design, plate thickness, lift and operating point – that is why we decide on the material only together with the valve calculation.
Oxygen: Oxygen compressors follow their own rules for material selection and cleanliness – see valves for oxygen.
Metal valve plates
Metal plates are the choice for high discharge temperatures, high pressure differences and clean gases. They are made of hardened stainless or spring steel and can be very thin, which keeps the valve compact.
- Strengths: highest temperature and pressure resistance, dimensionally stable, long proven.
- Weaknesses: sensitive to impact, dirt and liquid; damper plates are often needed; worn plates also wear the seat.
- Typical failure: fatigue fracture after flutter or hard impact – often starting at the slots or the plate ribs.
PEEK plates, rings and poppets
PEEK (polyether ether ketone) is today the most widely used non-metallic material for compressor valve sealing elements. It is light, absorbs impact and tolerates particles and droplets that would break a metal plate.
- Strengths: low moving mass, high impact tolerance, gentle on the seat, resistant to most process gases and condensate.
- Glass- or carbon-fibre reinforced PEEK for higher stiffness and strength, unfilled PEEK where maximum toughness matters.
- Poppets: in poppet valves PEEK is the standard material – each poppet moves on its own, so a damaged poppet does not stop the whole valve.
- Weaknesses: at very high temperatures and pressure differences the material can deform into the seat ports; it needs a greater thickness than metal.
- Typical failure: wear at the guide, deformation into the seat ports or edge breakage after liquid slugs.
PTFE sealing elements
Filled PTFE is used where chemical resistance matters more than strength. It withstands almost all media, has very low friction and runs without lubrication, but it is softer than PEEK and tends to creep under load.
- Strengths: outstanding chemical resistance, low friction, suitable for oil-free operation.
- Weaknesses: lower strength and stiffness; limited pressure difference and temperature.
- Typical failure: permanent deformation (creep) and wear at higher loads.
Damper plates and washers
Damper plates and washers cushion the opening impact of the sealing element against the guard and protect both parts. In metal plate valves they are often essential; with PEEK plates they can sometimes be omitted or made thinner. We supply them in metal or PEEK, matched to the plate and the lift.
Changing from metal to PEEK – what to watch out for
Replacing metal plates with PEEK plates of the same shape is not enough: mass, thickness and stiffness change, and with them the opening and closing behaviour of the valve.
- Thickness: a PEEK plate is usually thicker than a metal plate. Without adjustment the lift changes.
- Springs: the lighter plate needs a different spring force, otherwise it closes too early or flutters.
- Seat ports: wide ports may need additional support so the plate does not deform at high pressure difference.
- Operating point: temperature, pressure difference and gas are checked against the material limits.
That is why we recalculate the valve with our own simulation software before changing the material. More on valve design
Frequently asked questions
Is PEEK better than metal for compressor valve plates?
Not in general. PEEK is better where impact, dirt or liquid shorten the life of metal plates; metal remains the better choice at the highest temperatures and pressure differences. The decision depends on the operating point.
Can I simply replace metal plates with PEEK plates?
Only after checking the valve design. Thickness, mass and stiffness differ, so lift and spring force usually have to be adapted.
Do you supply PEEK poppets?
Yes. We supply PEEK poppets and complete poppet sets for poppet valves – to your drawing or from a sample.
Do you supply PEEK damper plates and washers?
Yes, in PEEK or metal, matched to the valve plate and the lift.
Glass-fibre or carbon-fibre reinforced PEEK?
Both increase stiffness and strength compared with unfilled PEEK. Which one fits depends on the gas, the temperature and the load on the plate; we select it as part of the valve calculation.
Do you supply original parts?
No. We supply parts suitable for compressors of many manufacturers, designed and specified under our own responsibility. They are not original parts, and we have no affiliation with these manufacturers.
Send us a drawing, photo or nameplate
Send whatever you have – drawing, photo of the sample, nameplate or operating data. We usually reply within 24 hours on working days and prepare a free, non-binding quotation for you.