venturi vacuum or vacuum pump 1

[Ballsache]

Hi,I would appreciate if any of you knowledge people can advise me which is more energy efficient.
I work in the beverage industry which uses filling, rinsing, labeling and case erection machines. Some machines use venturi systems for vacuum and others use vacuum pumps.
My questions are which system is more energy efficient, venturi or a pump?
What are the advantages/disadvantages/limitations between both?
Any other additional info would also be helpful.

Thanks in advance.
Steve

 

[globi5]

A vacuum pump is generally more efficient than a venturi system.

A venturi system has no moving parts and therefore no wear (and is probably costs less). Also, it requires less space and it is easy to clean.

 

[Artisi]

I don't think you can really say that a venturi system has no moving parts, what about the unit supplying the motive power for the venturi as this forms part of the whole? However, I would agree that a vacuum pump is more efficient than a venturi but it is debatable which has the lower maintenance requirement a vacuum pump or a compressor.

 

[FACS]

Shop air is always under constant demand.
We rebuild packaging machines and case erectors every month. We almost always take out the venturi and install a vacuum pump.

Venturis just make the compressor run more and more.. the vacuum pumps we use are now very reliable and need no maintenance.



Charlie

http://www.facsco.com

 

[green1959]

I have been involved with both vacuum pumps and Venturi Devices (Ejectors) and vacuum pumps for over 25 years now. In terms of thermodynamic efficiency, there is no contest. The vacuum pump will win every time. But, when selecting a vacuum producer, thermodynamic efficiency is not the only criteria used for selection.
It is true that Ejectors have no moving parts to wear out, thus maintenance is generally less. However, excessive moisture in the motive gas line can cause erosion, but spare parts can be easily fitted. In my experience it is far easier to fit a new nozzle and diffuser to an Ejector than having to dismantle a mechanical vacumm device where the tolerances are generally more critical.
Ejectors can be made from any material which can be machined or welded. This is of particular advantage in corrosive applications. On the other hand, I find the available material options for vacuum pumps is much more limited.
Ejectors can handle solid material and liquid slugs without incurring mechanical damage. The same is generally not true for all vacuum pumps.
Ejectors dont present an electrical hazard.
Although it is a bit dated now, have a look at Chapter 8 of Ryans and Roper "Process Vacuum System Design & Operation" McGraw-Hill 1986

 

[EdStainless]

For systems with low duty cycle, say that you only need vacuum 5% of the time, the an eductor is nice because it is easy to turn on and off. You can also position them right where the vacuum is needed so there are no vacuum lines, only compressed air.
I agreed with the efficiency statements to start, but if you compare a bunch of small vacuum pumps with one large compressor I am not so sure.

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