Sounds like we're getting ready to head down the shutter road again so I'll quickly sugest the Victaulic 77 series of air/water valves. These are all rubber inards with a simple gate valve in 1 - 2 inch sizes. A little creative welding could make a great emergency shut down I think.
Doug
I guess you won't have too much trouble with oil getting pulled in under high vacuum somewhere and dieseling with that engine.
Hopefully
I've seen a Detroit 149 run away and a 16 cylinder two-stroke at 1500RPM over high idle is something you don't want to be near. I did my apprenticeship at an open-cut coal mine and we had quite a few trucks with that engine in them. When we started one after an injector changeout one day, it just spun up .. and up .. and up. We didn't realise there was a problem until it went past high idle as they were used in a diesel-electric setup and used to sit at 1800rpm all day.
Holy cow! Abandon ship!
It was possibly the loudest engine note I have ever heard - and the old 149's were loud enough already! Everyone in the workshop scattered, but one brave soul ran up and flicked the switch that released the flaps on the top of the blowers and it dropped it's note for about 2 seconds, and of it went again misfiring all over the place - the blower oil seals were sucked in and it ran on it's own oil until it seized. Turns out someone had dropped a rocker bolt from one of the cylinders and it wedged into the rack at full fuel. The alternator logs showed it had reached 3650 RPM.
The funniest thing about it was that a day or two later, I was talking to one of the maintenance guys at the washplant - about 1/2 mile away - and when I mentioned the engine letting go he said, "Yeah, we were all in the cribroom having lunch and suddenly we could hear this wail over the noise of the plant, so we sprung up and hit the e-stop and the whole place ground to a halt... but the noise kept going! That's when we realised it wasn't us, it was you guys over at the workshop." They heard it let go over the noise of 7 stories worth of pumps, conveyors, centrifuges and vibratory screens.