positive air shut off, and e-brake

[Plowboy]

I'm wondering if an e-brake will function as a positive air shut off in an atmospere rich in hydrocarbons? The reason I ask is I am considering useing my truck for work in the oil and gas field and most companies require that diesels have this feature.



Plowboy

 

[Royal]

I beleive you need to shut off the air to a diesel . They normally use a gillitine shut off valve. If you can't shut off the air at the intake the engine will run away on the gas, etc. it breaths.

 

[RustyJC]

The positive air shutoff will require a positive sealing valve (if not "bubble-tight", darned near it!) on the intake (air) side of the engine. The large industrial diesel and dual-fuel engines our company manufactures use seated butterfly valves in the air piping between the turbo and aftercoolers.



Since an e-brake-equipped engine keeps running at idle even with the e-brake engaged, the e-brake-type valve would probably let too much air through to meet the positive shutoff criteria if installed on the inlet side of the engine.



Rusty

 

[JHansen]

I don't think that an E-brake would work for the reason that Rusty listed-the air seal isn't nearlly tight enough to shut the engine down if it got a good sniff of gas. I've got a Roda Deaco positive air shutoff on my truck-and I wouldn't be without it-way more peace of mind knowing it's there. I paid the extra couple hundred bucks to get automatic shutdown-there's a wire that ties to the alternator ahead of the rectifier to sense AC voltage off the windings. Of course this voltage increases as RPM increases-so you can set a shutdown point from it. When it's exceeded, the module throws the solenoid connected to the butterfly-and BOOM down she goes! Fact is if things go bad you're not always gonna be in the cab to throw the shutdown-this way you don't have to worry about it.



It's a relatively easy install too-I put mine in myself. Took about 4-5 hours with the wiring and all. Happy to answer any more questions you have about it-just drop me a line



Jason

 

[C.]

I have a Jacobs E-brake. When I installed it I made a mistake with the wiring. This mistake allowed the engine to rev up with the brake activated. In other words, the brake was on when the accelerator was depressed.

So, I do not see how an exhaust brake can prevent the engine from "running away" when breathing a combustible gas.

By the way I quickly repaired my wiring problem and I am very happy with the exhaust brake.

 

[hammong]

A solenoid-activated guillotine valve just up-stream of the turbo is the best and safest way to go. When your ignition switch is in the "on" position, the solenoid opens the gate. When you turn off the ignition, the gate springs back to the closed-position.



The automatic control mechanism mentioned earlier sounds pretty nifty! I wonder if there is a "reasonably priced" commercial circuit for this application.



Greg

 

[Plowboy]

What's the average cost of a pos air shut off?

 

[JHansen]

Mine was worth around $1100 CDN-that's with the automatic shutoff apparatus. Cable-pull model was a little over $200 cheaper. Not real cheap-but well worth it if it saves your life. My brother had a runaway on a truck he drove in the 'patch-pretty sure the manual shutoff saved his life... unfortunately not the motor.



Hammong's theory of operation would definitely be the way to go-fail-safe operation. Unfortunately Roda Deaco's works the opposite way-the solenoid is energized to close the valve. Possibly they figured that a continuous-duty solenoid would add quite a bit of cost-or they had problems finding one that would live-or the electrical draw was too great. Whatever-the air-tripped ones I had when I drove tank truck used air only to throw the trip-they were held open by a pawl-type mechanism until an electric solenoid valve was thrown to supply air to a cylinder on the valve itself-then a spring closed off the butterfly. You have to test on a regular basis. And inspect the alternator signal wire constantly to make sure it's still intact.



Hope this helps you

Jason