Can anyone advise?

I would like to pick the brains of any one out there who is aware of, or knows of an instrument for measuring the water content of oil in circulation. The oil is going through a plate heat exchanger and in the past it ihas been experienced that Sea Water is getting into the oil, it would be of great benefit to know about sea water ingress as soon as it occurs in order to stop said ingress. Is there such an instument?

I have been looking at the Vaisala MM70. I have never tried it myself, but the write up looks promising.

Dreebs,
I have been looking the Vaisala Also. However I have previus good experiences with the Hydac Aqua Sensor. This unit reads percentage of saturation of water at a certain temperature; this means that this unit is capable of tell you exactlly when water is gettin in your systems. The AS also have comunication capabilities to a PLC.

Sorry. I compltlly gorget to give you the equipment URL, here you will find more information.
http://www.hydacusa.com/fluid/as.htm

Is it really the percentage or irrespective of percenatge if there is water contamination of the oil. Secondly does the system runs for 24X7?There are transducers sensing water and I HAVE SEEN ONE INSTALLED IN a 2000 T OIL HYD press.
regards

If you are just looking for a moisture sensor for the purpose of detecting moisture ingress where analysing quantities is not important then there are a number of units available. In Australia, units start form about $AU3000.00.
Try:
www.pall.com
www.hiac.com
www.hydac.com
www.ucc.co.uk
Most units give a real time display and can be fitted with remote alarms that are triggered when a preset level is exceeded.
There are plenty of units out there and it definately pays to shop around. I hope this is of some help.

In addition to the MC post, some units cam be conected to a PLC. This upload the readings to virtually averywere you want it.
Other options are on-off switches, this feature can be use in conjuction with a vacuum dehidrator for example. They unit will turn on the water separation device when is requiered and will turn it off when the levels are the right ones again.