What kind of pump/fan do you use to recirculate flammable gases?

Question

Sorry I'm a pump novice.

I've got a large pipe full of flammable gas/air mixture that I need to recirculate in order to ensure it's fully mixed. What kind of pump is best suited for this, and what kind of safety certification should it have?

Answer 1

The correct answer is found in NEC code: Class 1, Division 1.

For vapors, find a blower/compressor that is Class 1, Div 1 rated and it will be safe for the flammable atmosphere.

Answer 2

pump is used for liquid flow

your mixture is vapor or gas flow that need coppressor . centrifugal compressor

pump can't handle vapor flow

if your flow is liquid you should use centrifugal pump according to API610 standard.

Answer 3

perhaps use an Aspirator pump?. Also been led to believe that they are really good at mixing fluids. (it may be mixed well enough so you don't need to recirculate the mixture)

Don't think the pump efficiencies, or pressures, are that high, but as the only moving parts are the fluids themselves they are simple and very robust.

Still need to pressurise the motive gas.... If you're using a gas main, or bottled gas, the pressure could come from there, otherwise you'll need some kind of compressor that can handle that gas. Should be a lot less demanding with a "pure" gas because you wouldn't be dealing with an explosive mixture.

(Think the nozzle/air hole on a Bunsen burner has some of the features of an aspirator pump, ie the fast moving gas, helps induce an air flow)

As to safety it'll probably something along the lines of making sure the pump doesn't create a spark which can ignite the gas. (if an aspirator's body is metal, you shouldn't get a static build up)

If an explosion does happen,that the pump body shouldn't  explode (or be in a box which prevents metal shards flying everywhere). perhaps a rupture plate could be used to control where the system ruptures. Also a lot easier/cheeper replacing a "pipe cap", than it is the pipes/pump.

May need some kind of flashback arrestor to limit flame propagation. The Davy Safety Lamp (used in Coal mines) just used a wire gauze for this. May be enough for your use.

Answer 4

Sounds dangerous. You are brave to ask (or might actually even take the advice from) the general public for this situation.

Answer 5

?

Answer 6

heat resistant fan with a sealed motor to stop ignition of gasses fan is offset with remote drive via motor, good luck

Answer 7

Sounds like a dangerous idea. Normally your air and fuel mixes in the burning chamber. If you run the mix through a fan and there is a spark, goodbye equipment.

Answer 8

What you got to look for may be an explosion proof fan similar to that used in mine ventilation  though  in small scale.

You also get  fans (axial and centrifugal) whose motors are mounted out side the stream of gas but these too need to be  explosion proof .There is a version called bifurcated fans  where the motor is  inside the  fan but  physically isolated from the stream of air (used in  restaurant kitchens to remove hot, greasy and flammable  fumes).

If the  mixture is flamable  the gas carrying ducts or pipes will  also have to have air tight  joints. A lot will depend on the gas mixture pressure.