Rapid changes in pressure were also phoned through to collieries from the Met Office.

That's interesting. But does it still happen? The Met Office now being commercially minded and charging money for information that was previously freely available.

I've long retired from the Met. Office ( It's had a commercial arm for many years) but all weather companies are commercially minded so I doubt any would supply information without charge. Foreby that it wouldn't be that difficult these days to set up something as relatively simple as this independently considering the amount of instrumentation and information that is freely available. Well perhaps not the instrumentation but it's not that expensive.

And of course are there any deep pits still operational in the UK? I don't know about arrangements in the rest of the world but I'm sure there will be something in place.

---

Regarding Gresford had a quick look and it looks unlikely that any low pressure system pssed close at the time although one would need more detail. An idea of the chart a couple of hours prior to the explosion. Then again the weather immediately prior to the explosion might not have been relevant or perhaps vapour pressure had a role to play. Would I be correct in assuming the cause of the explosion was never firmly established?

🔗Personal-Album-272-Image-76794[linkphoto]Personal-Album-272-Image-76794[/linkphoto][/link]

---

...all weather companies are commercially minded so I doubt any would supply information without charge.

And of course are there any deep pits still operational in the UK? I don't know about arrangements in the rest of the world but I'm sure there will be something in place.

Plenty of weather information available free on the internet.

Also available is information on operational mines in the UK. I'm surprised you need to ask.

Of course there is plenty of weather information available on the web. In fact it's a classic information overload example. It just depends how site specific and how much in advance you require the info. That might not be quite so easy to disseminate.

What I basically meant to say was that there very few deep pits left although obviously this doesn't mean all pecautions should not be taken. The disaster in South Africa proved that.

---

Regarding Gresford had a quick look and it looks unlikely that any low pressure system pssed close at the time although one would need more detail. An idea of the chart a couple of hours prior to the explosion. Then again the weather immediately prior to the explosion might not have been relevant or perhaps vapour pressure had a role to play. Would I be correct in assuming the cause of the explosion was never firmly established?

🔗Personal-Album-272-Image-76794[linkphoto]Personal-Album-272-Image-76794[/linkphoto][/link]

Yes, as far as I understand, the cause of the explosion was never firmly established, and I haven't seen anything which even brings weather systems into the equation, apart from mention of rain, and then only in the context of the relatives, friends etc, waiting in the pouring rain. (How accurate this bit of information actually is , I don't know without some further research) I don't think low pressure weather systems were ever considered a contributing factor (someone please correct me if you know otherwise or have seen some more info somewhere) : - Just a wild guess on my part.
After so many years we will sadly never know the cause(s) for certain.

---

Problem with researching a hypothesis like this is lack of data.

1) Mine accidents are comparatively rare.
2) The records aren't available
3) There are too many other factors operating to be able to sensibly seperate the effect of air pressure.

Be aware of the scientists' nostrum: the plural of 'anecdote' is NOT 'data'.
Sadly in most cases, anecdotal evidence is all you have.

Problem with researching a hypothesis like this is lack of data.

1) Mine accidents are comparatively rare.
2) The records aren't available
3) There are too many other factors operating to be able to sensibly seperate the effect of air pressure.

Be aware of the scientists' nostrum: the plural of 'anecdote' is NOT 'data'.
Sadly in most cases, anecdotal evidence is all you have.

I agee with the points you are making to a certain extent. This certainly applies with 19th century explosions where data is extremely limited, so in a sense you have to extrapolate backwards. This is of course difficult as for one thing safety regulations then were far less stringent then than the current day.

However the latest study I've come across, the South African study already mentioned, was written in 1992 and covered the previous twenty years and lack of data wasn't so much a problem. This is the abstract from the study. Actually I've just found a copy online if anyone is interested so I'll include the link. A word of warning when looking at the pressure graphs. They foxed me for a while until I realised he was using the actual pressure at Jan Smuts airport which is at 5,558 feet!

The main purpose of the paper is to determine the contribution of fluctuations in barometric pressure to flammable gas explosions in South African mines. For this purpose, the barometric-pressure patterns preceding each of the 59 major explosions in South African gold and coal mines over the past 20 years were analysed. It is concluded that diurnal fluctuations in pressure do not have a major influence on the accumulation of gas in the underground workings, but that pressure drops associated with cyclonic weather systems moving across the country over a number of days are the major factor contributing to gas explosions in mines. To illustrate some of the points made in the paper, the Hlobane Colliery explosion of September 1983 is used as a case study. In the final section, several general conclusions are drawn and recommendations put forward as to how mines should recognize and react to meteorological phenomena that may lead to an increased probability of gas explosions in underground workings.

http://www.saimm.co.za/Journal/v092n05p131.pdf 

At the end of the day one is left with frustrating question. In how many of the many explosions during the Victorian ere did the weather play a significant role? Actually I should have mentioned that in his introduction he does make some interesting references to early British coal mine explosions.

---

I seem to remember seeing in some of the earliest Mine Inspectors reports records of barometric pressure in particular areas. For anyone looking for Met records relating to particular incidents, these would be held in the Met Office archives which are held at Devon Record Office. Also I have seen published daily records and charts from the 1920's & 1930's, published by HMSO.

Interesting topic and one which would be empirically easy to determine.

How does LEL and HEL vary with air pressure?

You could also say:-

How does LEL and HEL vary with air concentration?

As O2 concentration is reduced, LEL goes up and HEL comes down, until there is no longer an explosive limit, because combustion isn't supported.

So, then you would go onto how methane leaches out of the rocks and this would be hugely variable with the type of surrounding rock, the type of coal, the overburden and probably the +/- 5% of air pressure from average wouldn't do very much to alter the methane limits within the usual and quite mine-specific amounts.

It would suggest from basic chemistry that high atmospheric pressure would increase the effective concentration of O2, which would make the lower explosive limit as low as possible. However, the lowest atmospheric pressure would give the greatest dP for degassing of the rocks.

What you probably want is a huge low, followed by a mega high perhaps supported by chaps working air tools to create the most explosive environment.

Rather than looking at historical data, I would look at methane readings (from a modern gas meter) in Coal Mines and see how the data stacks up.

I seem to remember seeing in some of the earliest Mine Inspectors reports records of barometric pressure in particular areas. For anyone looking for Met records relating to particular incidents, these would be held in the Met Office archives which are held at Devon Record Office. Also I have seen published daily records and charts from the 1920's & 1930's, published by HMSO.

I'm not sure to which years you refer but I'm sure you are correct. After the 1872 Mines Act the years 1873-80 were the worst in history with 28 serious explosions causing 1769 deaths and 263 minor ones causing 464 deaths. In January 1881 Colliery Warnings were introduced and an immense improvement became noticeable.

---

Interesting topic and one which would be empirically easy to determine.

In his detailed paper, "Atmospheric Conditions and Explosions in Coal Mines", April 1957, C.B. McIntosh did a fair bit of empirical work on both methane and coal dust. These are American coal mines.

The moisture content of the coal dust varies according to the vapour pressure of the air. This in turn is dependent on the type of air mass. Cutting to the chase this can broken down to seasonal (fairly obvious) and the hours after the passage of a cold front when dry cooler air replaces warm moist air.

He quoted two comparatively recent major explosions in Illinois (Centralia and West Frakfort) which occurred after the mines had been under the influence of cold-dry air for 25 to 30 hr following a deep low pressure passage. Dust was the important explosive element in both these explosions.

He also noted in some detail the occasions when explosions had occurred at two different mines on the same day, or the day after, that were influenced by the same weather system.

I'd filed this research away now it's out again. Perhaps time for some more digging. 🙂

---

Near Scorrier, there is a very interesting mine with one open shaft. There is a fair bit of decaying wood in there and the air varies between pretty nasty and deadly.

A chum and I decided that after a series of weather fronts had gone over and it was very high pressure, it was safe to go in. It wasn't and both of us were nearly killed.

It turned out that the recent lack of rain had hampered the pathways which removed CO2.

Lesson:- Over simplification can be very dangerous.

Near Scorrier, there is a very interesting mine with one open shaft. There is a fair bit of decaying wood in there and the air varies between pretty nasty and deadly.

A chum and I decided that after a series of weather fronts had gone over and it was very high pressure, it was safe to go in. It wasn't and both of us were nearly killed.

It turned out that the recent lack of rain had hampered the pathways which removed CO2.

Lesson:- Over simplification can be very dangerous.

Out of interest, Stuey, what kind of mine was this, apart from a nasty one? 😞

---