Diesel exhaust as compressed air?

[allenr]

I have a Honda GD410(cc) stationary air cooled diesel which drives a Ford Prefect chassis and driveline (ancient British car).
It has two seats, low to the ground on the RHS, facing out to the side and sliding in and out on sliding door tracks.

I use it for training vines, attaching drip hose to wires, etc.

I've recently fitted a air cylinder to the front (drivers) seat to push the seat out when the next vine is reached. (spring return)

Now I need some compressed air. I've started fitting a compressor and air reciever but can't help wondering whether I could just direct the engine exhaust into the reciever and then (may have to make my own) fit a large diameter pressure relief valve.

Trials in the workshop indicate that 30 - 40psi should be ample to operate the cylinder.

I suspect most of you will scream "don't", but I'd particularly like to hear from those who've maybe tried something like this.

When you think about it, an exhaust brake on a truck engine is applying the same back pressure.

 

[patrick_g]

I have a Honda GD410(cc) stationary air cooled diesel which drives a Ford Prefect chassis and driveline (ancient British car).
It has two seats, low to the ground on the RHS, facing out to the side and sliding in and out on sliding door tracks.

I use it for training vines, attaching drip hose to wires, etc.

I've recently fitted a air cylinder to the front (drivers) seat to push the seat out when the next vine is reached. (spring return)

Now I need some compressed air. I've started fitting a compressor and air reciever but can't help wondering whether I could just direct the engine exhaust into the reciever and then (may have to make my own) fit a large diameter pressure relief valve.

Trials in the workshop indicate that 30 - 40psi should be ample to operate the cylinder.

I suspect most of you will scream "don't", but I'd particularly like to hear from those who've maybe tried something like this.

When you think about it, an exhaust brake on a truck engine is applying the same back pressure.

The problem here and the reason I will say don't do it is not ALL about hurting the engine. I have used exhaust brakes on a Cummins B5.9 diesel. HD valve springs were available for that application or else your retarding (braking force) would be quite reduced.

You won't get a lot of pressure (safely, for your engine) without HD valve springs.

That said, there is another good reason not to do it even if the engine would not be harmed. Diesel exhaust is really dirty and even if you run a cat converter or after burner there are lots of nasty chemicals left. I would not want to blow all that CRAP (Chemically Reactive Air Pollutants) into my nice home brew pneudraulic system and have to deal with corrosion and dirty residue. The condensate from the exhaust will dissolve pollutants and produce acids. I suppose you could use materials resistant to the acids and abrasive effects of the carbon but it could get quite expensive.

An electric compressor with accumulator tank or engine driven (belt) compressor (even an old A/C compressor) would be my choices for consideration.

I used to have a Schrader brand (or was it Dunlop???) braid covered rubber hose with a tire chuck on one end and some adapters to fit spark plug holes on the other end to be used in the field for emergency inflation of tires. If I recall correctly the instructions (I know, I know, who reads instructions?) cautioned you to deflate and reinflate with "proper" air when available. I carried it for years and years in my 1943 Jeep and then in my 3/4 ton CornBinder/homebrew motorhome and NEVER used it.

Pat

 

[Egon]

The amount and pressure of air required will probably be a very determining factor.

You can do it and you may do it but if you should do it is another question?

Not having seen such a use of diesel exhaust in commercial operations may be an indication of whether you should do it.

You may consider an exhaust driven compressor. That is viable and is very common to many diesel engines but may not build the pressure you wish.

Other alternatives may be a belt driven or electric driven compressor.

 

[patrick_g]

Thanks for agreeing with me, Egon.

Pat

 

[allenr]

Thanks Patrick G and Egon, for your thoughts.

I've decided to not try it.

Stationary diesels are probably not the cleanest burning engines around and the thought of particulates clogging the reciever and cylinder doesn't appeal to me either.

 

[weedpharma]

Has anyone used an airconditioner compressor for this job? Once you have fitted a pressure relief valve and pressure switch, you can turn the drive to the compressor on and off to maintain the desired pressure. Just a thought.

Weedpharma

 

[mwb]

Do you require position control? Pnumatics are nice for speed but it might be a little rough on your application if the load varies (sticky mechanism, etc). This seat thing you have might become an 'ejection seat' if pressure builds. It may be easier, more controllable and safer to adapt a small hydraulic (splitter) pump and use a hydraulic cylinder? Having hydraulics available might have other uses for you also.

 

[john_bud]

Has anyone used an airconditioner compressor for this job? Once you have fitted a pressure relief valve and pressure switch, you can turn the drive to the compressor on and off to maintain the desired pressure. Just a thought.

Weedpharma

Sure, done all the time. Check out the jeep forums for oba on board air.

jb

 

[allenr]

Thanks Weedpharma,MWB and John Bud for your thoughts.

 

[jake98]

Is there any possibility that we could see a picture of that operation?