Dear epeters,

In principle, the same blower can be used for a vacuum application as well as for a pressure application, as long as the pressure ratio of that application is the same.

(high vacuum needs a pre-inlet blower)

The only difference is the direction of the pressure drop over the shaft seals.

It might be, that the shaft seals of a vacuum blower are differently arranged than in a pressure blower.

Ask the manufacturer.

success

teus ■

There is no problem I have done it many times; just change the inlet to outlet. Ask the manufacture to give you performance curve for exhauster. This will make your life easier to set the air flow and motor size. If noise is critical you might need a silencer on the outlet. ■

Dear Mantoo,

The inlet of the blower stays the inlet.

Normally the inlet has a bigger flange than the outlet.

Changing the inlet and outlet requires also a change in rotation direction.

Or are you referring to the inlet and outlet of the vacuum system rather than the blower?

The power for a blower in vacuum or pressure is almost the same as long as the pressure drop is the same.

The outlet temperature is depending on the pressure ratio, which is the limiting operational factor.

Shaft seal is an issue to consider with the manufacturer, because there are several arrangements available.

To epeters:

If you let me know the blower parameters:

Make and type

volume per rotation

rpm

specific air leakage in m3/min at 100 mbar pressure difference

vacuum

I can calculate a performance curve with power consumption

all for now

teus ■

Dear Mr Teus

The change is at the blower / exhauster and indeed it will require a bigger flange. As far as seals are concerned almost all of the blowers from reputed manufactures I have worked with have lip seals on the drive shaft and labyrinth seal inside. If the duty is changed from positive to negative pressure the seals are good up to 1000 mbar and to 500 mbar vac. ■

dear Mr Mantoo,

I am still a little bit puzzled about the inlet and outlet question.

The connections involved are:

sytem inlet and system outlet

blower inlet and blower outlet

in a pressure system:

blower inlet atmospheric suction

blower outlet connected to the system inlet

system outlet to atmospheric

In a vacuum system:

System inlet from atmosphere

system outlet connected to the blower inlet

blower outlet to atmosphere.

The blower is then still running in the same direction from blower inlet to blower outlet

see also sketch

Am I right?

best regards

teus ■

here the file

teus

Attachments

pressure-vacuumsystem model (1) (ZIP)

■

I thought we were only talking about the blower, if it could be used as an exhauster!!! That is what I am talking about; not about changing pressure conveying system to a vacuum conveying system. ■

dear Mr Mantoo,

Now I understand.

I understood the original question as referring to a vacuum conveying system, where a pressure rated blower was to applied.

best regards

teus ■

dear epeters,

The Aerzen GM 130L has labyrinth shaft seals and should work properly in vacuum- as well in pressure mode.

The GM130L can handle only 400 mbar vacuum.

pressure ratio 1/06 = 1.67

In pressure mode the overpressure is 600 mbar

pressure ratio

1.6 / 1 = 1.6

For deeper vacuum, a pre-inlet blower is required.

nevertheless, you should contact Aerzen to answer your questions. I know that they are very cooperative at Aerzen.

As we are not aware of the details of your application, it is difficult to give a clear answer, but it seems OK as long as your vacuum system does not require special blower properties.

best regards

teus ■