Inlet vacuum filters come in a number of types and are essential to protect rotary vane pumps from particulate entering through the inlet and causing damage to the pump. Various grades and types of inlet filter are available depending on the application. Hospital or laboratory applications generally use bacterial grade filters as this not only protects the pump, but also protects staff from bacteria that might otherwise travel through the pump and out into the plant room atmosphere.
It is most important to ensure that filter elements are changed when either differential pressure becomes too high or at the manufacturer’s recommendation, which is usually six to twelve months. High differential pressure signifies a blocked filter and can have a severe effect on the performance of the pump. Filter elements that are left unchanged often suffer a breakdown of the media, which renders them useless due to their pores enlarging, which then shows no differential pressure loss. This is often mistaken for a clean filter, when in fact it is the equivalent of no filter, which can lead to damage to the rotary vane vacuum pump or in the case of a bacterial filter, the passing through of bacteria into the plant room environment.