2020 POTD Thread Archive

[GoceKU]

This will be my last post on the subject. Pits can be very useful. They also can be hazardous. There are the obvious falling hazards. Many gases or vapors are heavier than air, such as argon, butane, propane, hexane, chlorine, petrol vapor, and carbon dioxide. These gasses can accumulate in the pit. Also, if some petrol were to spill, it can create a surprising amount of vapors. If you were to bend over, say to pick up something you dropped, or worse, you bumped your head and fell to the bottom of the pit it is possible you would suffocate and die. With a fan or some sort of forced ventilation, it might stir up enough air to mix and dilute the vapors and make it safer.

We all want to enjoy your future posts, so please be careful whenever in the pit. Carry on, you have posted some really interesting projects!

This is some useful advice, won't it be better if i have a turbine fan at the lowes point to extract the air and gasses at the bottom of the pit ?

 

[WobblyHand]

Yes, some kind of fan at the bottom to extract fumes would be a very good idea. That fan should be explosion proof, or at least not have sparking brushes!

 

[GoceKU]

I think this will fit that description, AC induction motor, cast iron and aluminium body, i will start to plan for it.

 

[WobblyHand]

Well that's amazing! (Fast too!) Was that in your garage? What does it come from?
You have access to a lot of interesting stuff.

 

[GoceKU]

I have no idea what is it from, it is very dusty inside, so probably air extraction or steel forge. Yeah, i get lucky from time to time to find interesting staff.

 

[hman]

Just a note of caution ... True, induction motors don't have sparky brushes. But they do have a centrifugal switch, which opens during startup, and can cause a spark. All of us are thinking of your continued safety!

 

[Weldingrod1]

Why dont you cast in a 4" pvc pipe to the bottom and set your fan above ground level, blowing down the pipe and then having air rise. Eliminates the explosion hazard, at least until you get the vapors distributed up top ;-)
Might also plumb in an air line and a 1/2" pvc line to pump it out.

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[Boswell]

set your fan above ground level

Putting the fan outside of the pit and blowing air into the pit is a much better solution in my opinion that having the fan in the pit. Not only do you reduce the explosion risk but you are also guaranteed to be delivering breathable air into the pit and not just recirculating bad air.

 

[pontiac428]

Pit bays are very common in Europe. The only requirement for an inspected commercial build is an exhaust vent. I can't remember the spec off the top of my head, but I'm thinking it works out to 25 CFM or so. Otherwise, I don't think of pits as being any more dangerous than a post lift. I've worked on some spectacularly heavy equipment in pit bays that I don't think would be even possible to do with any kind of hoist.

 

[DavidR8]

TIGed up my first actual part: a cable hanger for my welding cart.
Cut a length of 2” pipe and then cut a plate to hold the cable on.
Darn hard to control the arc as it seemed to want to ‘blow’ over the edge.

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