A QB2 is controlling pressure to the dome of a ratio regulator in this high pressure leak test application. This allows the QB2 to use shop air to control much higher pressures. The PUT (Part Under Test) is pressurized and then a solenoid valve closes pressure while decay is measured by an external transducer.
We often use ratio regulators for high pressure applications. This is because our 2-loop concept virtually eliminates the hysteresis and mechanical inaccuracies to control pressure around ±0.5% of full scale calibration.
This high pressure leak test can be setup for pressure decay or flow measurement when dynamic conditions must be met and sustained. Often, a small leak is acceptable and measuring flow is a great way to determine the actual leak rate for quality control.