How to control the Fridge Return flow (GV and GV Bypass)

There are two paths for the fridge return flow.

   
1. Gate Valve Bypass (GV-bypass)

Options:
1. Absolute moves by percent: Enter the set point (in %) and press "ENTER". The boxes to the right allow you to do increments in terms of +/-1, +/-5, +/-10.
2. Absolute moves by turns    : Enter the number of turns set-point, and press "ENTER". The boxes to the right allow you to do increments in terms of +/-0.01, +/-0.05, +/-0.1.
3. Auto Control with Pressure: Click the "Toggle Switch" shown in the Purple box (see below) to enable the PID control on the Fridge Pressure by providing the set-point in Torr.
4. Fully Open/Close : Use the "Full Open" button or "Full Close" button as needed (see the two yellow arrows towards the upper-left of the following picture).

2. Gate Valve (GV)
 
IMPORTANT: Please check with the Target Expert on Shift before opening the GV.
*  Do not open the GV,
(1) if the fridge is at atmospheric pressure or above (0.5 psi)
                              and
(2) if the GV-Bypass was not opened before.

* If the fridge is above atmospheric pressure (or ~0.5psi), then turn OFF the roots-pumps while the Rotary Vane pump (backing pump) is still running. After that, while keeping the GV closed, open GV-Bypass valve with the steps of 20% until the fridge pressure is below 100 Torr, and then fully open the GV-Bypass.

Configurations

    Configuration when the GV is "Closed"

   
  
   
    Configuration when the GV is "Open"