Metal finishing Q&As since 1989

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Water based fluid in bladder accumulator, bag lube effects

2002

Company supplies hydraulic power unit (HPU) that use Macdermid Canning HW540 fluid or water based glycol mix with agents within. The HPU use bladder type accumulators. The bladder supplier use a lube oil between the bladder and accumulator shell. We are required to flush the entire system to NAS Class 6 cleanliness, hence the accumulators do get "washed" with a flushing/cleaning fluid, and lube is washed out. After the accumulator is placed in service, the water/glycol mix enters the system at high pressure (5,000 psig nominal). The bag or bladder is folded or pinched, due to lack of lubricant.

Can anyone offer a suggestion? The fluid can not be changed, must be the HW540 fluid and must be clean. Perhaps a water based lube or grease may be applied to the bladder and not washed by the HW540 fluid.

The bladder is viton, the accumulator wall is coated with phenolic coating, for water service.

Comments please.

H. C. Cotham, III
- Houston, Texas

Maybe a fluorine-terminated silicone would do the trick. There are many silicones available which might meet your compatibility requirements. Time to do a web search for custom silicone lubricant suppliers?

Dale Woika
Surface Conversion Sciences - Bellefonte, Pennsylvania
2002