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exploding petrol tank


Unkel Kunkel
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11 minutes ago, Colin Lindsay said:

This is a problematic one because it's a non-tapered brass thread into a metal housing, but it has to align with a solid pipe, and when you align it to the pipe it's not fully tightened. I can tighten it up fully airtight, but then it's half an inch out from the pipe and has to be loosened again to meet. If I bend the pipe, it's quite a large bore and flared at both ends, and so if bent further might become too short to seal - I'd try that as a last resort.

If I use a flexible sealant it has to be able to withstand the air pressure inside the tank. PTFE is no good; tried and failed. What you can see round the base of the brass fitting in the photo further up is a rubber seal I fitted, but it made no difference. I might just end up using a good solid sealer and if it's permanent, then I suppose I have to ask: when am I intending to remove that valve ever again?

84B03B25-03C2-4715-9DC2-CCA15F7A4FD4_1_105_c.jpg.f18ee10677a174866dda172afce1d75b.jpg D41F5675-5FB4-45AD-960E-A0454DA50E0C_1_105_c.jpg.2251f65b536c7ecc3acefa1623cc22da.jpg

Have you considered removing the "reducing" ferule?. Making good the conection with the Brass Fitting and then putting the Thread tape on the Ferrule to complete the seal.?. You may then be able to get better alignment with the pipe?.

Pete

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As an aside. Powders, Flour is one, have been known to spontaeously combust in a violent manner, again you have Fuel, (Flour) Air, and often static electricity. 

Probably why most of the gears in a flour mill are wooden? 

 

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On 12/02/2021 at 11:41, JohnD said:

PeteH,

Most interested in your last para.      Please explain why WD40 or similar is such bad news (I suggested it!) and what is meant by "light ends"?

I have a rather different professional interest.   A few years ago, not in my hospital, an oxygen cylinder, the lightweight GRP type, was turned on and laid on a patient's bed in preparation for them to be moved elsewhere on the bed.      A few seconds later, a 'bang' was heard and three feet of flame came out of the cylinder nozzle!      It burnt the patient, set light to the bed clothes and the curtains around the bed, ans started amajor fire in the Intensive care unit.     Several other people, staff and patients had smoke inhalation injuries, only mitigated by heroic action by the staff.     The ICU had to be closed for redecoration, but I never heard of any explanation.   See: https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/full/10.1111/anae.12089   

 High-pressure oxygen is an extreme fire risk, yes, but what ignited it?           Aluminium fragments in the cylinder?    

  We become blase about the use of high concentrations of oxygen.        So blase, that it killed three US astronauts, Grissom, White and Chaffee in the Apollo 1 disaster.    Afterward the ICU incident, The Health and Safety Executive changed the protocol for the use of transport cylinders to say that they should never be used while laid on their side, always upright in the approved rack.      I should reassure everyone that this is a unique incident - there are millions of such cylinders in safe use in the NHS. 

John

There was another  similar incident following this 2011  ITU  one.

This was in the midlands in May 2020 when paramedics attended a 67 year  old woman  her home with suspected Covid.As the valve of the oxygen cylinder was opened a fire started and quickly engulfed the room and the house burnt down.Although the paramedics and others in the house escaped, tragically, the  woman did not.

 It is likely that the paramedics would be using a similar type “integral valve”light weight cylinder , usually CD size - like the burnt out one in the ITU

They are not moly.steel , they are  alloy.

In one case, the cylinder was horizontal.This is advised against.

In both cases there is a description of “sparks” showering out of the opened valve -which may be  very relevant.

However, millions  of oxygen cylinders are in use in UK and are refilled an enormous number of times per year so  such terrible  incidents  are really extremely rare.

19DD964A-1BC5-40AF-8A92-8708960C1C5D.jpeg

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I recall being told (probably on a fire training course) that the expanding CO2 from a fire extinguisher can sometimes create enough static electricity to produce sparks at the nozzle. On a fire extinguisher that's pretty harmless but presumably oxygen cylinders must be designed to avoid it.

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48 minutes ago, Pete Lewis said:

of line ...........but the idea of a fart now seems  i bit  dangerous !!!

but probably determined by pressure velocity and orifice  parameters ???

sorry getting bored again 

pete

That's why your major orifices are about three feet apart and point in opposite directions, so you can smoke and fart at the same time without any danger.

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Thanks, Unkel!       Gosh, that story got buried in the Covid furore - it would normally lead the front pages.    And the Medicines and Healthcare products Agency rep knew of three incidents!  So there is another!

The standard rack to hold such a transport cylinder upright is designed to hang on a bed.    I've seen them in a sling, carried over the shoulder, more or less vertical, or a back pack, or attached to a wheel chair, but what are paramedics to do?  Care for the patient impeded by the small but significant weight of the cylinder, or lay it down?      AFAIK, there is no light sturdy stand for paramedics to support such a cylinder in an upright position in a patient's home.

Come on guys and gilrls!  We're the innovative, amateur engineers!    Can you design such a stand?   It must be light.    Plastic or even cardboard and even disposable, or in a light, folding metal form.    A CD oxygen cylinder is 500m long, by 100mm in diameter and weighs 3.5kgs.    Go to it!

John

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On 14/02/2021 at 12:40, JohnD said:

Thanks, Unkel!       Gosh, that story got buried in the Covid furore - it would normally lead the front pages.    And the Medicines and Healthcare products Agency rep knew of three incidents!  So there is another!

The standard rack to hold such a transport cylinder upright is designed to hang on a bed.    I've seen them in a sling, carried over the shoulder, more or less vertical, or a back pack, or attached to a wheel chair, but what are paramedics to do?  Care for the patient impeded by the small but significant weight of the cylinder, or lay it down?      AFAIK, there is no light sturdy stand for paramedics to support such a cylinder in an upright position in a patient's home.

Come on guys and gilrls!  We're the innovative, amateur engineers!    Can you design such a stand?   It must be light.    Plastic or even cardboard and even disposable, or in a light, folding metal form.    A CD oxygen cylinder is 500m long, by 100mm in diameter and weighs 3.5kgs.    Go to it!

John

I shouldn't have started this, John!

I am puzzled why  there should be an  issue about the cylinder being horizontal-and why “sparks” if not burning alloy or something?

I can understand  where a gas is liquefied  you could get a cold jet of liquefied gas or with a mixture of gases (like N2O and Oxygen  as Entonox) it could   “laminate “ at cool temp so you get more of one than t’other until turned warmed etc,

but this is oxygen, way above its critical temperature therefore is all gas -whether the valve is vertical, horizontal or upside down ?

 

 

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7 hours ago, PeteH said:

Interesting read:- https://www.hse.gov.uk/pubns/indg459.pdf

Also gives clues to the foregoing "hazards"

Pete

That’s comprehensive.

Amongst the “don’ts” it includes “ starting diesel engines “.

One can but only wonder what catastrophe prompted it’s  inclusion.

About  20 years ago , Hyperbaric oxygen was seen by some as a  panacea  and life extender (not withstanding its legitimate roles in  nitrogen narcosis ,carbon monoxide poisoning etc.)

 There was a chap who rented a lock-up about half a mile from here.He installed his own  DIY hyperbaric oxygen chamber /cylinder.

In an attempt  to enhance his health and life,it all went disastrously wrong.

It wasn’t fully decided how it happened, but he died in a very ferocious conflagration  unable to escape his hyperbaric  cylinder..

 

 

 

 

 

 

 

 

 

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3 hours ago, Unkel Kunkel said:

Amongst the “don’ts” it includes “ starting diesel engines “.

One can but only wonder what catastrophe prompted it’s  inclusion.

Cannot say definitively, But "air starting" of large Diesel`s (Circa 600psi) is quite commonplace, I supect "somone" has attempted to so do with an Oxygen Cylinder?. The result would be catastrophic!!.

Pete

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6 hours ago, Colin Lindsay said:

Is that the same kind of oxygen tent thingy that Michael Jackson used to sleep in?

There are pictures of him in a hyperbaric chamber. 

The pressure in these typically 1- 2 atmospheric pressure and higher than normal oxygen concentration 

A “tent” is what it sounds like and not significantly  pressured but increased oxygen concentration..- I don’t know if he had one of those.

Some athletes even  use “altitude” training in a “tent “ by being in one of these for  varying periods of time with reduced  oxygen levels in the belief it will make their muscles utilise oxygen  better and enhance their performance.

Don’t know if MJ slept in his chamber,but was quoted as saying it would make him live longer  ( “a hundred and fifty tears”)

- well clearly that didn’t work out as he had hoped...

Taking various drugs and additionally  getting a private doctor to give him propofol,  an intravenous general anaesthetic without any monitoring, to help him get a good nights sleep, clearly had an adverse  affect on his life expectancy.

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19 hours ago, Unkel Kunkel said:

Amongst the “don’ts” it includes “ starting diesel engines “.

Some Diesel engines have compressed-air start. Including those intended for use in hazardous areas ironically.

Compressed nitrogen may also be used and it’s easy to see how someone faced with the practical problem of getting his engine going and a row of quite similar looking bottles of compressed gas might do something daft (even though the threads on oxygen bottles are intentionally different). Especially if he had no idea that it may be a bad idea.

I imagine the results are fairly spectacular and possibly involve a Darwin Award.

Nick

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