[TheForge] Re: cutting propane cylinders- fuel-air mixture

[jack andrews]

Hi,

I have been following the discussion on the problems associated with 
used propane bottles and forwarded them to Mike Porter, author of "Gas 
Burners for Forges, Furnaces, and Kilns." He an expert on this. Mikey 
has had problems getting back on theforge and so he has asked me to 
forward the following.

best

Jack Andrews



Begin forwarded message:

> From: Keporter at aol.com
> Date: March 31, 2005 1:32:49 AM EST
> To: skipjack394 at mchsi.com
> Subject: Re: TheForge Digest, Vol 14, Issue 65
>
> Jack
> As I've said, every attempt I made for six straight months to get back 
> on the list, ended with my emails bounced. So, if you could post this 
> for me?
>  

> Hi, all
> Filling the propane tank with water to just below the cut line is done 
> for the simple reason that no significant ignition can take place with 
> water displacing air/gas in most of the tank's space. CO2 purging is 
> fine if you have a meter to check the gas inside the tank, or if you 
> have experience. For people who just want to do this trick for the 
> first time with peace of mind, water leaves no room for doubt :-)
>     In order of importance, the biggest explosive hazard is the 
> possibility of propane vapor left sitting in the tank--this, water 
> displaces. The next possible hazard is the tarry mess on the some tank 
> bottoms, which can be substantial; when heated it can be turned into a 
> combustible vapor. Out gassing of propane in the metal does not seem 
> to be a significant source for combustible fumes. However, since 
> propane is soluble in water, even that possibility is taken care of 
> with water purging.
>     The biggest advantage of water purging is that, once the first 
> large opening is made, there is no inclosed space left to generate 
> explosive pressures anymore. So, even if you mess up and cut away the 
> top of the tank first (where no tars and waxes can collect), leaving 
> the possible tarry mess on the bottom to be cut through without the 
> benefit of a water purge, the worst that can happen is a little flame 
> and smoke, so long as you don't set the cut end on a flat surface, 
> thus effectively sealing it, your good to go. Use bricks or dunnage to 
> raise the cut end off the surface it sets on.
> Mike Porter