Operating Temperature and Exposure
Review continuous temperature, short-term peaks and their duration, together with heating and cooling cycles.
Extended heat exposure can affect material properties and elastic recovery. At low temperatures, hardening and contraction can reduce the seal’s ability to follow movement or maintain contact, particularly during cold starts or low-pressure operation.
A published temperature range is a selection reference, not a guaranteed operating range for every finished O-ring. Performance in hot air does not necessarily represent performance in hot oil, steam or process chemicals.
Media, Additives and Cleaning Exposure
Identify the exact fluid, concentration, mixtures, additives and cleaning agents. Chemical exposure may cause swelling, shrinkage, hardening or changes in mechanical properties.
Conventional FKM compounds may be unsuitable for certain ketones, amines, low-molecular-weight esters and ethers. Hot water and steam also require careful assessment. Specialized formulations can behave differently, so these limitations should not be applied identically to every FKM compound.
Even when two O-rings are both described as FKM, the proposed compounded material may need confirmation for the specific media, temperature and sealing conditions. Matching colour or nominal hardness alone does not establish equivalence.
Compatibility guides provide a starting point. Where available evidence does not adequately represent the application, testing under representative conditions may be needed.
