This measures the purity of the outside tank from the HR3. The value should be approximately equal (or very close) to the measured purity at the outside tank.
- Ensure the pressure reading on the pressure indicator P10 shows positive pressure (preferably > 20 psig).
- Connect one side of the plastic tube to L3 (Helium purge inlet), and let the other end of the plastic tube disconnect from the purity meter.
(This is to avoid any dust/oil/contaminants directly going into the purity meter at the first flow through the plastic tube). - Crack open "Vmup" and let some gHe flow through the plastic tube, and then reduce the flow to check the purity.
- Turn ON the purity meter while there is a low gHe flow through the tube.
- Connect the 'free' end of the plastic tube to the purity meter, and measure the purity.