Defoamers
Circulating two-phase or three-phase fluids generates foam that causes problems within the machine. Removing the cause of the problem will achieve the best results, but chemical treatment with defoamers is a useful back up.
The two main culprits, surface foam and entrained air in the fluid, need different defoamer types:
Oil-based Very good on surface foam
Water-based Very good on entrained air
Synthetic Effective on both types, but expensive
Houghton offers all product types, and is continually developing improved grades which are economical, effective against surface and entrained air foams, and have minimal impact on the Yankee cylinder coating.