Membrane ventilation pump

A membrane vacuum pump is a membrane pump as a venting device of fire pumps of the fire services .

function

The diaphragm ventilation pump is connected on the suction side via ventilation channels directly to the pressure side of the fire fighting centrifugal pump (front-mounted pumps) or by lines (rear pumps).

construction

The diaphragm bleeding pump consists of a pump housing with suction channels and inlet valves, an eccentric which is mounted directly on the impeller shaft, two piston rods with diaphragm plates , outlet valves and pressure springs.

Working method

The eccentric is driven directly by the impeller shaft. When bleeding (“sucking in”) the piston rod with the diaphragm plate is pressed outwards by the eccentric against the spring force. The resulting negative pressure opens the inlet valve and the air flows from the centrifugal fire pump into the suction chamber. During the ejection stroke, the piston rod with the diaphragm plate is pressed inwards by the compression spring. This creates overpressure which closes the inlet valve. At the same time, the outlet valve opens and the air is forced out through the outlet channel. The vent pump is switched off at an output pressure of approx. 2 to 3 bar. The piston rod with diaphragm plate is in the outer position and closes the outlet valve.

The diaphragm ventilation pump achieves its best performance at about half the maximum speed.

literature

• Training course for centrifugal fire pumps at the Münster fire brigade
• Centrifugal fire pumps. In: Hans Kemper: machinist for fire engines - basics. Hüthig Jehle Rehm: 2009, ISBN 978-3-609620-12-1 , page 56 ff. (With illustration on page 59)