Circuit or sensor design to measure PH of fluids???

[fastline]

We are working on a meter to test PH of water soluble machining fluids. Range does not move much from 7 but should stay alkaline. If they move towards acidic, there are problems. We already have a circuit that we use for general sensor measurements but finding ready made PH sensors outrageous and kind of wondering what technologies are used to create a PH sensor?

Is this a difficult task? We already make some basic sensors such as J TCs, thermistors, etc and have the manufacturing capabilities. Just wondering how they are made.

Thanks

 

[Reloadron]

This is a good read on the subject. I am guessing from your post you want to measure the PH of cutting oils or the coolants used in CNC applications. I don't wander out to our machining areas any more much but have memories of the processes. Should this be true you have a few options but there is no option for the sensor as you need an industrial designed sensor made for the harsh environment it will be used in. From the sensor you can build or buy the signal conditioning and display sections. You will need a few standard buffer solutions to periodically test the probe and system as well as cleaning the probe periodically. Doing it right should make for a more consistent machining process.

Here is another read on a sensor by Omega Engineering. Before I forget, I can't stress the importance of good temperature compensation enough! Years ago I bought quite a bit from Cole Parmer if I recall correctly including buffer solutions.

<EDIT> Cole Parmer Stuff including some inexpensive hand held stuff. Really a matter of where you want to go with it. </EDIT>

Ron