Soft start valves are used to throttle the gas flow in roughing lines. They prevent turbulences in piping and containers, particulate contamination in vacuum installations, detachment of substrates by turbulences.
Soft Start Valve
Soft-start valves consist of two halves of throttle flaps supported on a common axis and maintained in the open position by a spring. The axis is held in an ISO-KF centering ring that is formed as a body with valve seat.
When mounting them between two ISO-KF flanges (instead of a centering ring), the open flaps must be orientated against the air flow in the vacuum line. When the roughing system goes into operation, a strong air flow occurs in the roughing line, which immediately closes the valve and reduces the pipe section by about 99%. When reaching a differental pressure of approx. 15 mbar, the valve opens and leaves the pipe sectionnearly unobstructed for further pumping.