Ventilation device (fire extinguishing system)
Venting devices are used to vent the feed lines of pumps.
In order to convey water with centrifugal pumps via a suction line , the air must first be removed from the suction hoses so that the water can flow in again.
Since the suction chamber and the pressure chamber of centrifugal fire extinguishing pumps are connected to one another, these pumps cannot prime themselves and need their own venting device to remove water from open waters to vent the suction line.
A distinction is made between venting devices that are put into operation manually by the machinist and fully automatic devices that switch themselves on and off again when required.
Types
The designs are diverse and range from the historical capsule slide pump to exhaust ejector systems to modern diaphragm ventilation pumps .
Piston and hand piston priming pumps
Liquid ring priming pump
Dry ring priming pump
Membrane ventilation pump
Exhaust ejector systems (gas ejectors)
A distinction is made here between single-stage and two-stage gas ejectors, which work on the principle of jet pumps :
1. single-stage gas ejector
With the help of a lever, the pump vent valve is opened and the flap in the exhaust line is closed, whereby the exhaust gases are led through an ejector. Since the exhaust gases are chased from the propellant nozzle into the collector nozzle at high speed, a negative pressure is created which then draws the air from the pump into the exhaust pipe (ejector principle). As a result, the pump and the suction pipe are vented so that the water is pressed into the pump by the atmospheric air pressure and the pump can then deliver water. This principle only works at high engine speeds during the intake process.
2. two-stage gas ejector
A two-stage gas jet, on the other hand, has two propulsion nozzles connected in series. The first works like the single-stage gas heater, the second with outside air. When venting, the exhaust gases not only create a negative pressure at the exhaust nozzle, but also a pressure gradient to the outside atmosphere, whereby both stages support the suction process.
Individual evidence
- ↑ Training of volunteer fire brigades - machinist for fire engines , State Fire Brigade School Baden-Württemberg, Neckarverlag, 2002