Hydraulic oil Temperature Sensing

AutomationDirect has a thermocouple to 4-20ma signal conditioner here: http://web3.automationdirect.com/adc/Shopping/Catalog/Process_Controls/Signal_Conditioners/FC-T1

Thanks Bernie!
I was going to check out the Automation direct website.
I didn't know what they were called Signal Conditioners

:site:

Another suggestion is to use an RTD instead of a thermocouple. Perfectly adequate for the temperature ranges you are looking at, and they are less prone to noise and don't require special wire or terminal blocks. Here is the signal conditioner for them:

http://web3.automationdirect.com/adc/Shopping/Catalog/Process_Controls/Signal_Conditioners/FC-R1

Another possibilty is a device from Dill Instruments I've used for this service many times. They even have an RTD with a built in 4-20 mA transmitter.

http://www.dillinstruments.com/4-20.html

A very economical solution would be to use one of these:

http://www.ifmefector.com/ifmus/web/temp_a02.htm

Its an integrated temperature sensor/transmitter - you can mount it in a well or directly in the oil. Its availalbe with analog outputs and switch points as well. I used them on hydraulic oil tanks and have been happy with the performance.