Vacuum for filtration

A vacuum system for an entire factory will probably use steam jets. Vacuum for just one unit very often comes from a Nash-Hytor pump.

The casing of the pump is elliptical. As rotation drives the liquid to the walls, the gas volume changes. Where the gas volume is largest and the pressure lowest, gas can enter. As it rotates to the constricted region, it is compressed and exits.

This pump is ideal for mixtures of gas and liquid as in filtration. It fails when there is no liquid in the pump, but filtration sends a fully humidified gas that will not evaporate the liquid. There is very often some entrained water anyway to replenish what might leave the pump.

Web site from which the following photos were captured

Photo of precoated filter

while on sabbatical leave at ESB, Porto, Portugal, 1996