The concern I had regarding the amount of voltage applied to the lining of our vessels has diminished considerably since I obtained the Operating Sheet for the Calibrator. The instructions are pretty much what you alluded to in your post. Statements such as “may vary between 200-400V per Mil of thickness” and “to adjust sensitivity, reduce sensitivity somewhat” and “there is approx. ¼” spark difference between starting voltage and breaking voltage”, indicates that there is no exact voltage measurement possible between coating applications. It would drive someone with a desire to “measure” actual voltage, batty. The calibrator gets you in the ballpark with the generator settings. So, I can have the machine set to deliver a voltage between 2 to 4kV for a 10 Mils of coating. 4kV-8kV for 20 mils and so on. We typically apply a minimum of 60 mils up to 80-100 mils. It’s a spray and bake operation. You can do the math. One good thing came from this, besides peace of mind. Whoever wrote our work instruction saying we apply 6000-8000 Volts to our lining must have only read the first sentence, or were out to lunch. As I was simulating the spark gap we usually use, the calibrator was indicating approx. 25,000 Volts. I was verifying the procedure, before releasing it. We will put in the voltage ranges we may be obtaining in the procedure and simply scribe a reference mark on the power setting and the sensitivity setting to make sure that the knobs are in the same location all the time. (approx.) Once a quarter, we will verify the settings and ranges and document it. As for the Calibrator, I will probably send it out to the Manufacturer every two years for its own verification. Maybe three years. The use for this device is really to make sure that you are not applying excessive voltage/corona that could damage the lining and enough voltage to ensure that there are no pinholes or bare spots. There is a wide spread between the two parameters. Thanks for the response. If you see anything here that you think would cause an Auditor concern, let me know.
And, yes, we have self calibrating Coating Thickness Tester.