Low Pressure Acetylene Generator

Ibrahim, do not modify it!!!!!!!!!!!!!!!!!!!!1

Modifing the acetylene generator will get you or someone else killed. The simple thing to do is have a number of cylinders tied in together with a common manifold to store the gas and have reserves as the chemical exchange will only occur so fast no matter what.

acetylne explodes like TNT when compressed a little bit, so the cylinders you see are filled with a large surface area adsorbent that is wetted with acetone and the acetylene is gradually dissolved in the acetone at a low pressure. When you open it it fizzes out like CO2 from soda water. The only way to get a higher flow rate is to parallel more cylinders.

You know what they say: If you mess with something about which you do not know your ass from a hole in the ground, they will bury your ass in a hole in the ground

Aurizon:

Good post!

Most people who use acetylene aren't aware of what is in their tank.

In the U.S. regulations basically require a max pressure of no more than 15 psig, (we had to use 17-18 psig to get the necessary flows through a mass flow controller on one project), and the E.U. regs are I believe around 20 psig or so.

However, at pressures above approximately 28 psi acetylene gas becomes unstable and can decompose explosively! That is why it is so dangerous. The average regulator and gage can easily be a psi or 2 off. The higher pressure in the tank is only because, as you pointed out the acetylene is dissolved in acetone or a similar solvent.

Drawing acetylene from a tank too quickly (or not upright) can cause acetone to enter the hose.

The only safe way to increase flow is to manifold tanks together through a single, large enough capacity regulator, and use hoses of a sufficient ID and as short as possible. These parts are readily obtainable through your gas supplier.

As Greg's post and others have stated, the explosive decomposition danger of acetylene cannot be overemphasized. Acetylene compressors for filling of cylinders are built like proverbial outhouses to withstand internal explosions and are sometimes operated under water as a somewhat protective mass barrier in case a really severe explosion occurs. Cotton waste is often used in acetylene cylinders as a medium for soaking up the acetone in which the acetylene is dissolved.

From what I recall, the explosive tendancy emanates from the triple covalent bond between carbons, and the stress in those bonds due to the extreme angles involved. Acetylene is C2H2, and carbon has a valence of 4, whereas hydrogen has a valence of +1. Hence the triple bond between carbons.

Bernie Katz

I think you guys have missed the point. Ibrahim is talking about water tank acetylene generators, presumably he does not have easy access to cylinders.

These generators are designed to work with and up to a maximum load of carbide, if excess carbide is added acetylene will escape to atmosphere without exceeding 15 psi. If larger flow rates are needed more units should be paralleled together.

Extra weight could be added to the float cover but would be a problem if the demand was lowered whilst there was still a large amount of underacted carbide in the tank

I think those generators are self limiting and work like Kipp generators, as the pressure mounts it forces the water lower, and in time it bubbles out the bottom.

Any free water soon reacts to form acetylene so the carbid stack is fairly dry internally. These generators will have a maximum charge of carbide and will make gas until it is all depleted, and it may slow down near the end of the cycle, at which point you empty them and add another bunch of carbide. They may use premade carbide holders.

from these links you can see they are regulated and have a maximum rate. Not easy to change the rate. You need to use more units or a larger sized single unit.

http://apps.leg.wa.gov/WAC/default.aspx?cite=296-24-68211

http://www.google.ca/search?hl=en&q=%22acetylene+generator%22+%2Bcarbide

In 1966 fresh out of welding school I decided to refill my acetylene tank myself using an old generator I found stored in a warehouse. I ran a line from it to a fifty gallon drum which I thought would make a suitable collector, then to a small high pressure compressor and just attached the out line from the compressor through a checkvalve to the acetylene tank. I was very fortunate that I had left the shop to go to the mail box when the "event" occured. The device had not been running more than ten minutes or so when I left it, and I did notice that the pressure had reached about 20 lbs when I left the shop. I had just turned from the mailbox to go back to the shop when a yellow orange fireball the size of a railroad boxcar lifted the roof and shattered two of the masonary block walls sending tools, glass, cinderblock fragments and roofing shingles in all directions. I felt the heat and shock from nearly a hundred yards away, an electric drill which had been sitting in the window missed me by less than a couple feet, and my neighbors from as far as two miles came running to find out what happened. Fortunately I lived out in the farm country of south Jersey with no close neighbors, and no damage was done to anything other than my shop and pickup truck. My metal workbench which weighs about 150 lbs and which I still use wound up over a hundred feet away from the shop, where it had broken off the corner of a 300 gallon concrete watertrough. Let this be a warning! Nuff said!

Pls Ibrahim, i need such information for my project work, if you get it pls send me via email or phonecall. email: eunice4real2@hotmail.com

Hi Ibrahim

I am a caver, in New Zealand

We still use Acetylene generators for our lighting.

Carbide in the bottom compartment, water in the top tank drips down, Great system.

This is very low pressure and very safe. The generator hangs on our hip with the gas tube to the helmet and jet with pizzo started.

I have recently been restoring an old "Road side" Acetylene generator.

I would like to get it running but there are somethings I'm not sure about.

The Carbide drops down into a large quantity of water thus creating acetylene.

This unit has two cylinders on the side which the gas flows in the top down to the bottom of the first cylinder and up the second then to the appliance.

Are these cylinders for purifying/cleaning/dring the acetlene? What goes into these cylinders?

P.s

Yes I am aware of the dangers of C2H2

Hi!

The low pressure C2H2 generators used by the road side gas welders here in Nigeria is cheap compared to pressure cylinders. The generators are of two types: water to carbide and carbide to water; the classification is based on which of the material is added to the cylinder fisrt.

The most widely used type is d carbide to water; here fixed quantity of calcium carbide is added to a thick wall cylinder containing water, which is then sealed. The C2H2 gas generated has low pressure and is partially dried before it is used with oxygen purchased in cylinders. There is hardly any explosion so far as pressure is low.

During a study on the generators some problems were observed such as lack of standard design, low operating pressure, wet C2H2 gas, overflow of sludge, etc.

In order to solve some of the above mentioned problems, we plan to conduct a project to improve the low pressure generator. Iam a Lecturer in Mech. Eng Dept of the University of Abuja.

I need assistance from you and any other person. Hoping to hear from you soonest. My email address is: ibrahimuhd@yahoo.com.

Thanks.

Hi,

When I grew up on farm In Virginia in the thirties, we had an outside generator which supplied gas for lighting. Low pressure unit consisted of one inverted drum inside another which had water in it. The gas collected in the inverted drum which floated up and down on the cushion of gas; according to the volume. The pressure was almost constant because the weight of the drum remained almost the same. If the pressure got to great the drum was lifted and the excess bubbled out, regulated by the drum weight.

There was rod projecting from the drum which released more carbide when drum got to low.

The pressure was regulated by drum weight, and I was WELL instructed on that subject.

Mr Ibrahim,please contact to us: MDQ in free toll contact 0800 14041 17 or karbit@emdeki.com

Sincerely yours

• Hari Budiarto
  

What do the roadside welders use for oxygen?

Mark NSB