Unexpected vacuum ...

**Toolmaker51** · Mar 21, 2021, 09:25 PM

I don't think he saved the PTO either.

**machining 4 all** · Mar 22, 2021, 05:26 PM

I really didn't understand how he managed to do this!

**jdurand** · Mar 22, 2021, 06:22 PM

saved 5 minutes by not opening the vents.

A couple of years back I designed an air dehydrator for fuel oil tanks and we made SURE there was a nice big check valve in it for when the fast filled the tank. It wasn't possible to fast empty it so didn't need to worry in the suck direction.

**machining 4 all** · Mar 22, 2021, 06:37 PM

So it was human error ... Is there no way to automate this process or at least make it less prone to failure?

**Frank S** · Mar 22, 2021, 07:44 PM

Originally Posted by Toolmaker51

I don't think he saved the PTO either.

Some PTO driven rotary vacuum pumps have ceramic vanes in them others have a fiber vane set what happens is a sudden implosive loss of vacuum will mean the building negative pressure on one side of the vanes instantly becomes neutral or possibly a positive pressure causing the vanes to shatter inside of the groves of the rotor.
Now as to what should have been done to prevent this. First off the operator was not even in his vehicle to monitor any gages if he even had any to monitor.
As to what caused the implosion the suction line became blocked with solids somewhere along the length or most probably at a connection or valve. Quite possibly it may have never been opened in the first place after the operator had pre-charged his tanks with vacuum, in combination to this the relief vent valve would have had to fail. and about the only way those can fail is for the tanks to have been previously over filled or the sloshing of the materials in side the tanks had sloshed in transport and solidified on the vent stem and spring. Every time the tanks are emptied the operator is supposed to physically force the vents open and allow to close several times to insure nothing has built up on them. Since vacuum tanks are also pressure vessels since positive pressure is how they are emptied they would also have pressure relieving valves. the Vacuum pump is normally ran in reverse turning it into a compressor.
Operator training and maintenance are vital to these as well as any other type of machinery.

**Toolmaker51** · Mar 22, 2021, 08:16 PM

Didn't buy the rig, didn't pay attention to instructions, vague on responsibilities.
In lieu of operator training, this reinforces concept of owner/ operator superiority.

**machining 4 all** · Mar 23, 2021, 05:48 AM

Normally these cylinders are made of steel, what would be the average thickness of the plates? I question to get a sense of the effort required to cause this damage.

**Toolmaker51** · Mar 24, 2021, 02:10 PM

Originally Posted by machining 4 all

Normally these cylinders are made of steel, what would be the average thickness of the plates? I question to get a sense of the effort required to cause this damage.

Lol. Far less than thickness of his skull.
The sense, none.
The effort? Far less if compared explaining to his boss.

Others will ring in, but I'd expect tank walls not as thick we'd guess at. A lot of the strength comes from the shape, which also reduces sloshing, to ease driving.
So, I'll guess 3/16" inch. From the earlier responses, the real vacuum is in the pump, not the tank, acting as receiver.

**stillldoinit** · Mar 26, 2021, 06:47 AM

Doesn’t appear to be any internal support like slosh bulkheads. I used to use 55 gallon drums with a Venturi vacuum pump to empty coolant tanks on Cnc machines while still in the work force and saw several drums collapse. I would imagine the relief valve was stuck/seized closed. I wonder if they will try to pressurize it back out to salvage it. Should mount on a pedestal for a teaching tool for new drivers and also retraining.