Vacuum Pump Silencers

When a vacuum pump starts operating at normal atmospheric pressure, system pressure drop and power requirements are at their maximum. As the vacuum pump continues to evacuate the system, the inlet pressure decreases so the system pressure losses and power requirements decrease. The inlet volume flow in actual cubic feet per minute (ACFM) stays essentially constant throughout system operation, but because of decreasing inlet pressure, the discharge volume decreases until normal operating conditions are reached.

Envanio Universal designs and manufactures blower silencers in a wide range of standard sizes and configurations to meet diverse application needs. Engineered for global compatibility, they are available with most common pipe connection styles, including threaded, slip-fit, and flanged connections (ANSI, JIS, DIN, and more). Additional flexibility is provided through multiple mounting configurations, enabling seamless integration into virtually any blower package system design. ASME Code-compliant construction is also offered.

Separator-silencers meet their rated liquid separation efficiency at a nozzle velocity of 5,500 ft/min. At lower velocities their performance improves. At higher velocities their efficiency decreases. The nozzle velocity is the air velocity in the inlet or discharge nozzle and is equal to the actual volume flow rate (ACFM) divided by the nozzle area. Since the inlet volume flow rate is nearly constant during normal vacuum pump operation, the inlet separator-silencer should be sized so the velocity does not exceed 5,500 ft/min during all phases of operation. The discharge flow rate decreases from startup to normal operation, and in some applications, it may be acceptable to exceed a velocity of 5,500 ft/min during startup. If it is not acceptable to discharge liquid during startup, the velocity must be reduced.

If some liquid bypass is allowed during startup, the selection of the discharge separator-silencer should be based on pressure drop. Inlet and discharge separator-silencers require drain systems to remove the liquid. These systems (both inlet and discharge) must provide an adequate drain sealing system or liquid level to offset the vacuum on the inlet side and prevent blowout on the discharge side. See Tables 2 and 3 on the following page for liquid removal data.