The basic advantages of compressed air driven vacuum pumps are well known: small size, low weight, simple design, little maintenance, and wear resisting operation put them in first place when it comes to pick-and-place applications. The easy installation, control and free positioning make work easy with their quiet operation and neither heat nor oil mist emission.
MULTIJECTOR® – the multi stage venturi
But how do you increase efficiency of such a Venturi? How to keep the high vacuum and same energy need but give lots more of induced air (suction air)? Take a look at the picture of the MULTIJECTOR® to understand: A classical Venturi comes with a primary nozzle (injector), a secondary nozzle (diffuser) and a jet chamber (the gap between). The compressed air rushes through the primary nozzle, expands and accelerates, which causes a pressure drop. On its way towards the secondary nozzle it catches and mixes surrounding air and finally exits the Venturi through the secondary nozzle.
A MULTIJECTOR® comes with an advanced nozzle system, in which additional nozzles are placed in line with the primary and secondary nozzle. The suction air of each venturi stage mixed with the compressed air of the primary nozzle works as the gas jet for the following stage. For free and with no more air consumption. These additional Venturi stages don’t reach the high vacuum of the first, but their larger jet chambers produce an even higher suction volume. Still the vacuum pump reaches the high vacuum of the first Venturi stage, because flap valves close automatically in order of pressure balance between their certain Venturi stage and the collective vacuum chamber.
The special design of nozzles and aerodynamics gives Volkmann MULTIJECTOR vacuum pumps their unique efficiency: Common single stage Venturis perform at a ratio of 0.7:1 (suction air : needed compressed air). Modern Multijectors reach a ratio of up to 6:1. Take a MULTIJECTOR and save compressed air.
Energy consumption only in the suction cycle
In a vacuum conveyor the Multijector is turned on only during the suction cycle. While discharging the separator, the Multijector can easily be switched off. It requires no starting time for the next cycle like electrical pumps, also it has no wear during start and stop. The Multijector saves about 1/3 of compressed air during discharging, while electrical pumps need to run continuously and require additional vacuum valves to shut off the vacuum conveyor during discharging.
Volkmann offers various Multijector designs/series:
