A recent article in Fluid Power Journal provides a useful look at when an air compressor pump, combined with a venturi, is the best way to create a vacuum, and when an ordinary vacuum pump might be more efficient.
Both achieve approximately the same effect, but in many cases people specify a vacuum pump because they feel they do not have sufficient compressed air to work with a venturi.
The article asserts that this is often not true – and that substantial efficiency gains may be made by using air compressor pumps and venturis, rather than an always-on electric or hydraulic vacuum pump.
For example, the journal gives the situation of a vacuum-lifting application where suction is needed for three seconds in every 15.
A 0.25hp vacuum pump will typically run continuously throughout each 15-second cycle, whereas with a venturi, only three seconds of suction is needed, with a valve shutting off the compressed air for the remaining period.
This means a 0.9hp venturi would only use 0.18hp of compressed air, on average, for one fifth of the 15-second cycle.
As a result, the air compressor solution can be substantially more efficient than using an electric vacuum pump, particularly in such instances where the need for suction is periodic and not constant.
