Agilent Vacuum Pump Isolation Valves (VPI) are electrically connected in parallel with the mechanical pump, and close rapidly when power is interrupted to prevent oil backstreaming or particle migration into your vacuum system. These protection valves also vent the pump from the inlet side to push any debris towards the outlet, preventing it from being swept into the system when pumping is restarted. The body design and right-angle configuration provide maximum conductance.