I am just surfing the internet to find a good thing on our instrumentation device. Then I found this one of the ABB products. Portable pH Calibrator is using to simulate variable pH and also can be as pH analyzer and calibrator. It is extremely useful for grab sample pH measurement as well as bench setup and field calibration or troubleshooting of process pH analyzers.
When it comes to deal with process pH instrumentation, I personally thinking that this kind of calibrator is very essential and very good to have one. Very easy to use and the result can be much better. I am not sure how much it will cost. But you will save a lot of money when you can cut your cost to purchase buffer solution to do monthly calibration.