A Simple Way to Remove Water From Hydraulic Oil

HeadSpaceFlush-WaterEd Bailey, Bison Steel Inc., got and read The Hydraulic Maintenance Handbook and used the know-how within to deal with water contamination in a hydraulic shear. The oil capacity of the hydraulic tank was 300 gallons (1136 litres).

Initially the oil was circulated through water removal filters. Six filters were used but this only took out some of the water. A variation of the head space flush described in The Hydraulic Maintenance Handbook was then deployed.

The blower side of a shop vacuum was attached to the breather penetration in the tank lid. Air was blown into the head space and exhausted through a 1/2″ diameter hole at the other end of the tank’s head space.

The vacuum was run continuously, 24/7, for 12 days. During the day the shear was operated, which warmed up and circulated the oil in the hydraulic tank. The ambient air was about 30ºF (-1ºC) and the humidity was low.

The pictures below show oil samples taken at different stages of the process.

Oil samples taken at different stages of the water removal process.

From left to right:
1. Original contamination
2. After 6 filters.
3. After 60 hours of head space flush.
4. After 160 hours of head space flush.
5. After 260 hours of head space flush.

As you can see from the pictures, the water was essentially removed after about 160 hours of flushing the head space, and was only slightly better in appearance after 260 hours of flushing.

Sure, blowing unfiltered air through the reservoir head space is not ideal. But any resulting increase in load on the system’s particulate filters can be largely forgiven, because the process removed the water.

Based on an oil cost of (only!) $8/gallon, Ed’s modest investment in The Hydraulic Maintenance Handbook enabled him to save his employer $2,400.00 on this one maintenance problem alone. And that’s a bargain however you do the math.

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