Hydraulic oil emulsified by water ingress — steel plant, south-west China

Water entering a hydraulic system in south-west China emulsified the hydraulic oil and took cleanliness well outside specification. Emulsified oil is worse than dirty oil: the water carries through every valve and cylinder in the circuit, and the cleanliness reading that the plant relies on stops meaning anything. The system was still in production, so draining it and starting again was not on the table.

One pass on the nano ultra-clean screening unit, on site. The vacuum stage took the water out and the membrane stage took out what the water had carried in, so the two halves of the problem were handled in the same pass rather than in two separate steps with a drained reservoir in between.

Cleanliness of the contaminated oil reached NAS 7 in that single pass. It is not the cleanest number the range can produce, and it was not the number that was asked for: it was the number that brought a system in production back inside its own specification without a shutdown.