The above video shows how to properly set the rate of increase on a pressure chamber instrument using the Rate Valve. For the best measurement, the rate of increase should be 1/2 bar per second or less. This allows you to observe the end point and shut off the Control Valve with minimal error. A high rate of increase can cause a “false” reading that is higher than the true end point.
If you know that plant is under high stress and the pressure will be high, you can open the rate valve slightly, allowing a higher rate of increase and then slowing it down once you approach the known pressure range for the reading.
Care should be taken to NOT completely shut off the pressure with the rate valve. Completely shutting off the rate valve can cause damage to the needle inside as well as the packing around the needle.