Dig Face Ventilation

[sjt]

We are currently digging out a collapse in a heading off the main air circuit of a lead mine.

After a period of working in the area, we started to become short of breath, headachy etc.
When we dug 2 days back-to-back, this became even worse, and there is also a lot of shale which might be compounding the problem.

We've concluded forced ventilation of some sort is needed to make working conditions safe, and are hoping someone has dealt with a similar problem and can give some advice!
Have read a couple of the historic threads - did anyone come up with something that worked?

It's 15m or so back to the main drag where there is good airflow.
I understand we're better off sucking bad air out of the face rather than trying to blow air in.

Thoughts so far have ranged from 12v blowers or air compressors (either from a battery or powered by a drill), purging the air with dive cylinders with some kind of venturi setup, or building a set of box bellows.

Then there is the matter of what kind of pipe to use.

It's an SRT route to get to the dig, so whatever we do also needs to be reasonably portable, and conditions are fairly squalid, so it will need to be tough.

Thanks in advance!

 

[A_Northerner]

P8 Ben's Dig team have 3" PVC-coated aluminium ducting running down the pit, we use a boat bilge blower that's designed to remove flammable fumes from engine compartments. One of our more techy teammates has built a waterproof housing for a transformer/converter so we can run it off a drill battery. Voltage has to be stepped down because it was originally too strong! If you're still Derbs based, feel free to pop down P8 and have a look at it if you want a better idea.

10m of the ducting comes compressed down to ~50cm, so easy to take into a dig face and stretch out to the desired length. You can buy flanges to connect multiple lengths together. It feels tough enough that you'd need something sharp to properly pierce it.

 

[Pie Muncher]

"I understand we're better off sucking bad air out of the face rather than trying to blow air in."
It's more efficient to blow the bad air out, which will naturally be replaces with fresher air.

 

[LJR]

Try a battery powered leaf blower connected to polythene lay-flat tubing. The easiest tubing is food packaging stuff that comes in rolls. It is meant to be cut and heat welded with food in but you can roll out what you need and just let it sit on the floor or hold it up in the roof on springy bits of stick or drill rawlplug holes in the side/roof and suspend it using loops of the same stuff. Secure the open end around the leaf blower with bungee cord or a ratchet strap or cable ties.
You don't need to run the blower full time , just every so often to clear the fug at the face.

 

[sjt]

Try a battery powered leaf blower connected to polythene lay-flat tubing. The easiest tubing is food packaging stuff that comes in rolls. It is meant to be cut and heat welded with food in but you can roll out what you need and just let it sit on the floor or hold it up in the roof on springy bits of stick or drill rawlplug holes in the side/roof and suspend it using loops of the same stuff. Secure the open end around the leaf blower with bungee cord or a ratchet strap or cable ties.
You don't need to run the blower full time , just every so often to clear the fug at the face.

Magic, that'll do the trick!

Cheers

 

[ChrisB]

It sounds obvious, but make sure the bad air going out is nowhere near the clean air coming in! One of the big hotels in Manchester had a power cut, started up their diesel generator and it ran for 30 minutes and then died because it was breathing its exhaust.

 

[Loki]

Can you do a radon test? Does it pond up?

 

[sjt]

Can you do a radon test? Does it pond up?

I'm not sure I want to know!

 

[Leclused]

Pipe at the ceiling as far as possible and a ventilator blowing fresh air in. In one of our digs in France there is hanging about 30m of drainaige pipe. An old car-fan running on batteries provides the power for it.

Be sure that the pipe you has a flat inner surface to avoid air turbulance .

The iron pipe beside the air pipe is a part of the monorail on which the digging buckets are hanging to be pulled out.

Don't use flat tubes because you need extra power to inflate the tubes

 

[legendrider]

Sounds like tumble drier exhaust duct would be suitable for a 15m run. It concertinas down to nothing but can be hung from pins driven into the wall and wont collapse. if you are able to rig up a polythene sheet air door across the air circuit and run the duct through it, you wont need mechanical ventilation.

 

[wormster]

Tumble dryer duct, some 120mm computer fans and a battery??

Most commercial digging involves pushing air to the working face down the man shaft and exhaust fans on the up cast ore shaft

 

[Ad W]

Positive pressurisation at the dig face with good clean air piped in from somewhere else seems more sensible to me than depressurisation to suck bad air out. The latter matter might pull in more of bad air that is on the other side of the collapse. However, if the only source of bad air is your own respiration then either approach would work.

 

[legendrider]

We did a dig a few years ago, my mate Alex wombled a bunch of plastic snow-poles from the moor road where they'd been knocked over, lying by the side of the road. Car tyre inner tubes and cable ties to join them together. 4" soil pipe offcuts would work just as well - see local builders skip for details.

 

[Chris Curry]

My understanding is that you're better off blowing fresh air in, with the fan out in the good air and your ducting running into the dig. Also best to position the fan high up, so it's less likely to suck in any of the heavier CO2 you're displacing out of the dig. SUSS's setup at Ben's Dig in P8 a described by A_Northerner is gold standard, but anything along those lines should work. Layflat tubing is the most portable option but you will lose some power inflating it. The leaf blower suggestion is a good, easy, ready-made option, but I think you'd be better will a little fan drawing low current and running constantly than having to stop and blast large volumes of air in at intervals.

 

[legendrider]

While we're on the subject, does anyone know who attempted to dig Barneycraig Level about 20 years ago? They used layflat to pipe fresh air into this very wet, shaley, oxygen-depleted crosscut but did not manage to break through. Their dig is now behind numerous new falls and O2 is 12% at terminal collapse which is 1/2 mile short of Whitewood Vein.

 

[Bob Mehew]

Can you do a radon test? Does it pond up?

The legend of CO2 and radon ponding up is a myth. Read Badino's paper in the Journal of Cave & Karst Studies at page 101 for an explanation. Very simply put, CO2 appears to pond at certain locations because the influx rate from the source at that location is greater than the rate of loss from that location. Although most CO2 in caves is generated by water influx (which also carries the calcium bicarbonate used to generate formations and releasing CO2 at the same time), when a human or decaying vegetation is present, then that will also generate CO2. Irritatingly, I have lost the reference to a paper which neatly displayed a figure showing the processes which go on between the surface and the cave passage - does any one know of it?

 

[Space Doubt Caver]

The legend of CO2 and radon ponding up is a myth. Read Badino's paper in the Journal of Cave & Karst Studies at page 101 for an explanation. Very simply put, CO2 appears to pond at certain locations because the influx rate from the source at that location is greater than the rate of loss from that location. Although most CO2 in caves is generated by water influx (which also carries the calcium bicarbonate used to generate formations and releasing CO2 at the same time), when a human or decaying vegetation is present, then that will also generate CO2. Irritatingly, I have lost the reference to a paper which neatly displayed a figure showing the processes which go on between the surface and the cave passage - does any one know of it?

Interesting