Ventilation At The Digging Face

Hi Folks,

Working on a dig at the moment where we can only spend a maximum of 1.5hrs physically digging as we are running out of air.  I have thought of running a small compressor at the surface with a serious length of hose down to the dig.

Anyone come up with any better ideas?

Thanks in advance...
 

alastairgott

Well-known member
People digging in the western highway in the speedwell side of peak cavern are using some pumps to hand pump air to the dig face, taking it in turns. I'm sure they will be able to tell you more if they spot this.
 

mulucaver

Member
notdavidgilmour said:
Hi Folks,

Working on a dig at the moment where we can only spend a maximum of 1.5hrs physically digging as we are running out of air.  I have thought of running a small compressor at the surface with a serious length of hose down to the dig.

Anyone come up with any better ideas?

Thanks in advance...

On the PDMHS dif of Valley Shaft (110ft deep) we ventilated with a surface fan and used lay flat plastic, the type used for packing with heat sealing machines. Very cheap. http://www.discountlayflattubing.co.uk
You may not need a compressor, use an old fan out of a car heater and drive with a 12V battery.
We did the same on the Titan dig although IIRC the fan was hydraulically driven.
 

TheBitterEnd

Well-known member
If you have a compressor, it may be worth considering a venturi type air mover, they make a huge difference to the volume of air that gets moved. You may be able to fabricate your own.
 

Mr Mike

Active member
There is a dig down a mine in the North Pennines that uses a second hand bouncy castle air blower (picked up from a car boot sale )and 100mm domestic ventilation trunking. Works very well, and it is blowing at a distance of around 150m.
 

Bottlebank

New member
The Chunnel Dig in the Milky Way, now more commonly known as the DCC Extensions, was a bad air dig for a long time. We used, as someone else has suggested, an old car fan and a 12V battery to blow air from the beginnning of the dig through a solid wall tube to the end of it.
 

Aubrey

Member
We use a vacuum cleaner to suck the bad air from the bottom of the Lime Kiln dig out to the surface. The cleaner is a cheepo 1400w unit with all of the filters removed and gives a good airflow through 35mm flexi pipe. It is powered by a generator. We use a CO2 meter to check the air and it is interesting to monitor how the air changes.
With the bad air being removed from the bottom of the dig fresh air is drawn in from the surface. The passage and pitches are between half and one square meter cross section and there is minimal mixing of the good and bad air when sucking out from the bottom. Even in the horizontal section we can follow the threshold of the changing air where the CO2 level can be 1.5% in one position and over 6% a meter further on. It takes about half an hour to completely change the air in the dig.  Sometimes, when we are eager to get digging, we slowly follow the changing air down the passage, monitoring as we go.

 

sluka

New member
https://scontent-a-vie.xx.fbcdn.net/hphotos-ash3/1016817_390760914358491_1903978936_n.jpg

A bit better than plastic tube, but the principe is the same.
 

4bags

New member
Les W said:
at one dig on Mendip they use a vacuum cleaner to suck out the CO2...
Used At Gibbet's Brow with great effect - hose to the dig face is approximately 30m, minimal loss of suction (unless the end is in the flooded bit when the vacuum is started!). Run off a generator on the surface, and very effective - fresh air can find its way to the dig face from the surface after just a few minutes.
 

Rob

Well-known member
alastairgott said:
People digging in the western highway in the speedwell side of peak cavern are using some pumps to hand pump air to the dig face, taking it in turns. I'm sure they will be able to tell you more if they spot this.
Originally used battery powered fans, running off 12v makita drill batteries. Then extended this system with a hand powered fan (due to heading up hill for a change). This was all never very sufficient, really only adding a short amount to the trip...

Now the system is MUCH better and uses a piston type arrangement. The cylinder is a 250mm od pipe about 1.2m long and took much organisation to get it there. This is pumped by one person for ~50% of the time and provides plenty of air. Hrock on here is worth a pm if anyone is interested in further details...
 

John B

New member
When we were digging a shaft in Nickergrove Mine through clay with no ventilation, Tom Proctor built this pump
Tomsairpump_zps84afb7a4.jpg
.
It was made from readily available bits and pieces, and it worked wonderfully well. The pipes were sink pipe. No batteries, generator or anything other than a bit of muscle power.
 

Rob

Well-known member
John, very nice design and drawing.

For info, this is very similar to the Weston Highway piston pump, apart from ours is a dual action single purpose pump, in that both strokes suck air from the dig and pump it far away. Tom's design could provide an interesting modification, especially as so much of the dig is uphill now (i.e. pump fresh air to the end, whilst sucking bad air from the lowest point). Just need an extra 80m of pipe taking in.
 

hrock

New member
Thanks Rob, love the suggestion.  You provide the pipe and get it there; I can sort the rest.

But, some good points to remember:
In general, suck don't blow (it is more efficient for many reasons).
Use the biggest pipe you can get as the losses are large (although if you're using mains power instead of man power this is less of a problem).

I would recommend you do not get tempted to scrub the CO2 out as this will solve the problem short term, but will mean that rather than suffering the CO2 feeling bad, you stand a good chance of feeling fine till you get a bit sleepy and then curling up and going to sleep for ever due to lack of O2 (your body does not monitor O2 levels in the blood, it monitors CO2 and makes the assumption that lots of CO2 means low O2 and vice versa).
 

doughobbs

Member
John B said:
When we were digging a shaft in Nickergrove Mine through clay with no ventilation, Tom Proctor built this pump
.
It was made from readily available bits and pieces, and it worked wonderfully well. The pipes were sink pipe. No batteries, generator or anything other than a bit of muscle power.

It's like a big bike pump!  (y)
 

adep

Member
The problem you will have with any long runs of ducting, especially flexible ducting is the pressure drop it incurs and the fans ability to overcome that pressure loss, if the pressure loss is greater than what the fan can cope with then you will get no flow

I am a ventilation engineer by the way so sizing fans and pumps is what I do
 
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