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- - DONT FORGET TO OPEN YOUR HATCH!! (https://www.classadrivers.com/forum/anything-everything/27406-dont-forget-open-your-hatch.html)

Quote:

Originally Posted by silvan

just plain ol' air. Damn.

Actually it is called vacuum.

A one square foot column of air weighs 2121 lbs.

That's at 14.73 lbs per square inch.

http://en.wikipedia.org/wiki/Atmospheric_pressure

Containing the damage when a tank is collapsing is hard to do, if you are sitting in a drivers lounge while the tank is being unloaded by an Operator employeed by the receiver. Especially if the unit operator is someplace other than the unload spot!

Back in 1982, while fighting a fire at a Chevron Production facility outside of Evanston WY, I sucked in the tank of a 120 BBL water truck. the driver didn't open any of the vents on his tank...even though they were all air operated. The C-pump on my pump truck was pulling 30 Pounds of vacuum and that steel tank collapsed about 30 seconds after the driver opened the valve. I wish I had been a picture taker back then. It was the weirdest sound you can ever hear..even over the roaring of a detroit engine.

Quote:

Originally Posted by chapchap70

On a fuel oil truck, there is a vent that automatically opens when oil is removed from the tank (while making a delivery) so air can get back in. It seems strange to me that a hatch would have to be manually opened every time the truck is off loaded.

I guess a truck of that type is off loaded by gravity? I wonder how long it took from the time the first pop sounded until the driver was able to get to the valve and stop the flow?

I've heard that "pop" sound and it is scary. In my case, the vent got clogged or something while making a delivery using a PTO pump. I was able to immediately shut the flow off. I was fortunate enough to be able to wrestle the hatch open and the single dent popped back out. 8)

the older grease tankers dont have vents because they are insulated and the grease has to be kept hot to keep it in liquid form, it unloads by either the truck pto pump or the customers pump, on these tanks, if you hear the pop, you are done, the only thing you can do is get the hell away from it. some of the newer tanks do have a vent on the hatch, but since the grease on the outside gets cold and hardens, they will usually be plugged up. we just treat the tank like it doesnt even have one. I need to open the hatch anyway to see when it is empty.you cant really tell when the grease is done flowing by watching the hoses, they usually stay full and have to be drained

Would a vacuum pump truck work for grease?

Quote:

Originally Posted by chapchap70

Would a vacuum pump truck work for grease?

I doubt it, it usually has to be pumped quite a ways and up into a tank

Never having pulled tanks....I always wondered how the driver got dents up as high as some I've seen. Man thats not a good thing.

Quote:

Originally Posted by Phantom433a

Never having pulled tanks....I always wondered how the driver got dents up as high as some I've seen. Man thats not a good thing.

most of the dents are just dents from hitting something or dropping something, the insulated tankers have very thin outer layer of aluminum and it dents very easily

Re: DONT FORGET TO OPEN YOUR HATCH!!

Quote:

Originally Posted by Fredog

Or this will happen ( not my tank)

WOW!!!. I do mostly gravity drops, but occasionally still have the ole PTO fired up for pumping diesel to above ground tanks.

Those pics serve as a healthy reminder to never get too comfy (esp. remembering vent caps). Thanks for the great info!

I just happened to come across this video on youtube, and it made me think of this topic ...

http://www.youtube.com/watch?v=E_hci9vrvfw

granted, that's a rail car, but same idea would apply I guess.

--Dave.