Automatic air shut off valve...for oilfield work

http://pacbrake.com/valving-solutions/air-intake-shut-off-valves
There are a bunch of other ones.
Our trucks have them, not sure of make. Will grab a picture later on.

They're relatively simple to install if just using a kill switch but if you're needing one that's RPM-triggered it gets a touch more complicated. Can't help you on cost, it didn't come out of my pocket. Half of our trucks were specced with them from the constructor.

 

I had one installed in 2012 when Gibson first came up with that rule and it was about $4,500. I have heard they are about half that now, but don't know. At that time, they had only approved two company"s product and they were both from Canada (go figure). Also at that time, they had to be installed by a certified dealer and there were only like three in TX and one in OK that I knew of. I'm sure there are more now.

 

There are a number of manufacturers out there for posi-airs. Mighty Titan, Chalwyn, and Roda Deaco are a few that come to my mind. I've installed a lot of them on trucks and equipment. You have a few different options to activate them as well. Cheapest would be with a pull cable but you can also get them with air or electrical actuation. They are easy to install. Best place to mount them is between the air to air and the intake manifold.

I would stay away from the automatic Chalwyns (the yellow ones with the pull cable override) as they have a tendancy to blow their guts apart and go straight into your engine. We've lost 2 generator engines because of that.

 

as far as im concerned, all diesel motors should have a positive air shutdown, oilfield or not. If you blow a turbo seal and your motor is now running on its own oil, that e-stop might just save your motor. something to think about. and yes, stay away from chalwyns, we had em on a bunch of lightplants and gensets and had nothing but problems