Hot water resistance
#1 Which O-ring material is suitable for hot water?
Hot water or steam is a much more aggressive medium than it appears. Basically, the temperature resistance of a material (e.g. on data sheets) is only valid for the medium air .In our experience, many users do not know that the material temperature resistance only applies to air.
If we now assume hot water or steam as the medium, the maximum temperature resistance is significantly reduced.
As a guide for the hot water or steam resistance of O-ring materials we have compiled a table for you. Please note that these are approximate values. In particular, if your application should reach the limits of the material temperature limits, a precise test is necessary.
Important: When considering the maximum temperature resistance of a material, the saturation content of the water vapor must always be taken into account. The specified values are based on 100% saturated water vapor.
Material | Temperature resistance air | Temperature resistance steam |
|---|---|---|
NBR | 120°C | 80°C |
VMQ (silicone) | 200°C | 100°C |
FKM (VITON) | 200°C | 120°C |
EPDM | 150°C | 170°C |
FEP coated | 200°C | 200°C |
PTFE | 200°C | 200°C |
FFKM - ECOLAST NH5750 | 270°C | 210°C |
FFKM - ECOLAST NH5751 HT | 330°C | 230°C |
FFKM - ECOLAST NH5755 HT | 330°C | 260°C |
#2 EPDM and FFKM O-rings are the best choice for hot water
O-rings made of EPDM or FFKM are by far the best choice for hot water or steam applications.
Basically FEP coated and pure PTFE are also resistant to hot water, but the application must first allow the right rigid FEP and PTFE O-rings to be used.
EPDM is of particular interest, as its temperature resistance in water (170°C) is higher than in air (150°C). EPDM is also available in specific steam mixtures that can withstand temperatures of up to 200°C. If the steam is hotter than 200°C, the only solution is to use FFKM (perfluoro rubber). We have listed our 3 best FFKM compounds for steam applications (NH5750, NH5751 HT and NH5755 HT) in the table.
If you have a critical hot water application, you can of course contact us at any time. We will be happy to advise you.
Technical article on the hot water resistance of O-rings | Sealing Academy | Click here >>
