underwater cutter

[Iain Hamilton]

Originally Posted by RogerViking

myself and my regular buddy have decided to get ourselves an air operated anglegrinder to help save some brass we saw from been eaten by those nasty brass worms ,so we have hooked it up to some regs and lashed 2 15l cyls togeather for it to run off i was 'just wondering' has anyone done this before. the idea is to cut a hole in the plate aprox 2' sq .we tried it out last week on a shallow 15m dive.it cut hardend steel with nobother .at 40m whats the chances of a runtime on it of about 6mins.

if memory serves me correctly you need to be running pneumatic tools at 4-6 bar over ambient, you might want to increase the interstage pressure on the reg, you probably want it to run at 10-12 bar,

to calcualte your air consumption you will need to know the operating pressure of the device and its air consumption, probably quoted in CFM and the usable gas volume of the cylinders your using,

in a nutshell, multiply the quoted CFM by your opperating pressure (40m)
so say 5cfm on surface would become 25 cfm at 40 meters

multiply that figure by 28.32 to get your liters per minute

cylinder charge pressure minus depth of work absolute + tool operating pressure x 30L

to keep it simple we will asume your going to have cylinders pumped to 220 and the tool operates at 5bar on surface.

so 220b - 10b = 210b x 30L = 6300L of usable air

a gas use of 5 CFM on surface will become 25 CFM at a depth of 40m 25 CFM X 28.32 gives the LPM = 708 Liters of air per minute x 6 mins = 4248 L

or your 6300L will last you 8m.53s


PLEASE stay away from any kind of oxy-arc cutting unless your trained in its use UNDERWATER and potential dangers, they without doubt have the potential to be the most dangerous tool you can use underwater.

also bare in mind if you dont have a suitable commercial diving qualification its illegal to use power tools underwater.

[gobfish1]

also bare in mind if you dont have a suitable commercial diving qualification its illegal to use power tools underwater




well i did'nt know that ,,,,

im with you on not using broco if you dont know what your doing you may go bang ,,, vent vent vent ,,,

[Iain Hamilton]

Originally Posted by gobfish1

also bare in mind if you dont have a suitable commercial diving qualification its illegal to use power tools underwater




well i did'nt know that ,,,,

im with you on not using broco if you dont know what your doing you may go bang ,,, vent vent vent ,,,

I would almost go as far as saying you would need a surface supplied quallification, but would need to check before i commit to that one,

ahhh broco, although dangerous, defo the most fun ive had in the water with a hat on.

[gobfish1]

Originally Posted by Iain Hamilton

I would almost go as far as saying you would need a surface supplied quallification, but would need to check before i commit to that one,

ahhh broco, although dangerous, defo the most fun ive had in the water with a hat on.

had a look at broco a few years back we had a bit of scrap to move ,,
was going to use the small strike pots on end of rods, No need for amps or coms then, Just lots of o2 ,, We got a hard hat man in the end, split the money with him ,,, He had an old vick s gas torch , i think it used 3 gas s, need to turn them on and off in the right order or bang i think ,,,

like you said think is best left to the big boy ,,,

[gobfish1]

Originally Posted by gobfish1

had a look at broco a few years back we had a bit of scrap to move ,,
was going to use the small strik pots on end of rods no need for amps or coms then just lots of o2 ,, we got a hard hat man in the end split the money with him ,,, he had an old vick s i think it was 3 gas s need to turn them on and off in the right order or bang i think ,,,

like you said think is best left to the big boy ,,,

good thread over on rbw lads do some underwater cutting to get a bell ..

Two MN Divers make Lk Michigan History - Rebreather World Forums

[A. Berk]

Originally Posted by RogerViking

myself and my regular buddy have decided to get ourselves an air operated anglegrinder to help save some brass we saw from been eaten by those nasty brass worms ,so we have hooked it up to some regs and lashed 2 15l cyls togeather for it to run off i was 'just wondering' has anyone done this before. the idea is to cut a hole in the plate aprox 2' sq .we tried it out last week on a shallow 15m dive.it cut hardend steel with nobother .at 40m whats the chances of a runtime on it of about 6mins.

Roger, I think you'll find that its volume of air that you'll be short of not pressure. Thats why in the commie world we use hydraulic tools at depth. Air tools are OK for shallow stuff but at 40m - nah!

With regard to oxy-thermic cutting with the likes of Broco rods - stay away from it unless you have done a proper course in its use and you use it with surface communications. The likelyhood of a big bang is very real when using Broco - even with vent holes - its dangerous kit - THAT HAS TAKEN MANY LIVES

Berko

[nigelH]

Grease it up well...

I tried an air operated drill as the basis for a DPV.
First time out it worked.
Second time it didn't.
By the time I took it apart to see what had happened it was a block of rust.
The sea water just ate it.

It only cost me about £8 on ebay so I was more annoyed than out of pocket.

[RogerViking]

Originally Posted by gobfish1

also bare in mind if you dont have a suitable commercial diving qualification its illegal to use power tools underwater




well i did'nt know that ,,,,

im with you on not using broco if you dont know what your doing you may go bang ,,, vent vent vent ,,,

yeah i think il be steering clear of a broco ......i want to remain alive rather than been the only guy in my club thats on fire under water

were cuting the porthole off on sat i let you all know how we get on

[gobfish1]

Originally Posted by RogerViking

yeah i think il be steering clear of a broco ......i want to remain alive rather than been the only guy in my club thats on fire under water

were cuting the porthole off on sat i let you all know how we get on

good look with it m8