High pressure cylinder construction question

[taylorkh]

Seems I saw a while back an article/pictures or video showing the construction of high pressure gas cylinders. The thing which caught my attention was a restrictor built into the cylinder below the threads where the valve attaches. The idea being to reduce the flow rate in the event that the valve was sheared off a filled cylinder - thus minimizing the rocket effect.

Of course, now that I am looking for the source of this information, I can not find it. So...

Can anyone point me to a source of this information?

or

Did I just imagine this and need to patent the idea? :D

TIA,

Ken

[sunpeople]

I think the History channel or Discover channel ran a show on gas bottles, i think it was called how things are made or something like that and they showed how they make the bottles from start to finish.

[taylorkh]

Thanks sunpeople. I recall an episode on one of those shows where they made 20# propane tanks. Might have been one on high pressure cylinders as well.

Ken

[ptsideshow]

The idea being to reduce the flow rate in the event that the valve was sheared off a filled cylinder - thus minimizing the rocket effect.
Flow restrictors are now in all the new type propane cylinders, Not the high pressure cylinders. There are two or three types and styles of the and some work better than others.Can't remember which type sucs but the local LPG refill station at the LWS changes them out when they find them as with most of the BBQ grilles the shut off on the high setting as the flow is to much for their design. They caused a lot of problems, but were good for selling new BBQ grilles till the design flaw was figured out. They probably have all been replaced by now. Have to see if I still have one laying around.

They wouldn't work on high pressure cylinders, due to the fact that the product in the cylinders are used for so many different applications.

Just for cutting torch use, The flow rate can vary from 1/8"steel 12/14 SCFH to 18"steel 1000/1200 SCFH
Standard Cubic Feet/Hour
That is for a size 12 tip and at high gas flow withdrawal rates manifolding maybe required.

Even with other fuel gases the larger the tip the higher the flow rate

The smaller propane tanks are the ones with the flow resrtictors in them

And yes "How it's made" had a show, showing them making the high pressure cylinders in the deep draw type of forging and then spinning the neck on them.

One of the ones that takes stuff apart I think did the propane cylinders both the small plumbers type and a 10 or 20 pounder. One of those don't try this at home episodes :eek:.

If I can find the valve assembly from an oxy cylinder and the propane cylinder I will take pictures and post later.
:D

[taylorkh]

Thanks ptsideshow. I have pictures of cut away valves - showing the back seat etc. Sure wish I could remember where I saw or imagined the hp cylinder with a restrictor.

Ken

[Hotfoot]

I have cut quite a few cylinders open, and removed as many valves, and have never encountered a restrictor built into the cylinder itself. May have been some in the valves, but I wouldn't know the intended function of some of that "back" stuff on them. Conventional (oxygen, helium, argon, CO2, nitrogen) inert gas cylinders just have a hole drilled into the brass valve. The propane valves do have that long stem thing.:)

[ptsideshow]

Thanks ptsideshow. I have pictures of cut away valves - showing the back seat etc. Sure wish I could remember where I saw or imagined the hp cylinder with a restrictor.

Ken

It might have to do with the smaller medical gas specific cylinders with the use specific CGA vales on them like the small oxygen cylinders or the dental nitrous cylinders.
As the propane cylinders were to eliminate the danger of damaged hoses on the BBQ around the houses.
As the 20 pounders have had problems when used on high flow appliances such as gas forges and the larger burner torches, with the turbo boosts and the multi burner Grilles with single tank feeds etc.
:D

[ptsideshow]

Found two of the valves due to deteriorating weather conditions had to call off the expedition for the propane one.
Here are the small medical gas quick connect:

http://i35.photobucket.com/albums/d200/ptsideshow/assorted/DSCF9092.jpg

Oxygen valve from a 300cu ft cylinder:

http://i35.photobucket.com/albums/d200/ptsideshow/assorted/DSCF9086.jpg

They both have 2 part drive systems that operate the valve seat shut off. I figure it is because of the people that crank on the valve stems with the 2 foot pipe wrenches.

They only have to replace the top half the oxygen cylinder has a drive tang that fits into a slot in the valve seat screw the seat of the valve is also plastic so it can fail and the over pressure disk operate and lower the cylinder contents.

The medical gas valve stem is also a two parter, for the same reason. the seat is also a plastic material.
:D

[Roger]

Not all propane cylinders are required to have flow fuse. Above minimum size, forklift cylinders, and more.

Flow fuses have been uses for many years to prevent/limit injury and damage when hose breaks. Gas hoses to submarines had them more than 20 years ago. This could include High Pressure charging hoses. No way to accurately forecast hose failure.

Some cylinder valves have dip tubes.
All scuba cylinder valves have short dip tube to help keep loose particles in tank when upside down.
Propane cylinder valves have dip tube for charging bleed valve so you know when tank is 90% full when liquid is bleeding out.
Some CO2 cylinders have long dip tube supplying liquid CO2 for specific uses including CO2 fire extinguishers.

[Roger]

As I remember Propane cylinder flow fuse shuts if it's not upright with gas flowing.