Contaminated acetylene near the end of Vipr30L cylinders (anyone else noticed?)

[Ian159]

Hello,

Since the phase-out of old dissolved acetylene cylinders, I have moved on to the Vipr30L acetylene cylinders with integral regulators. It seems the only way you can have OA in a small shop in the UK these days.

One thing I notice is these cylinders seem to put out contaminated gas in the last few percent of capacity (unlike the old BOC style ones). Symptoms are acetylene cone getting longer and weld pool shrinking and filler not melting cleanly. This is 304L welding, so probably more sensitive than other materials to gas mixture. Soon as I get a new cylinder connected, everything gets much better again.

Anyone know what might be happening?

Thanks,
ian.

 

[voipio]

Acetylene is normally stored under pressure in cylinders as a gas dissolved in acetone, and this is further distributed in an inert matrix. As the acetylene is consumed during use, a small amount of acetone also enters the gas leaving the cylinder. This fraction of acetone leaving the cylinder increases as the acetylene is consumed, and can reach as much as 20% of the gas mixture leaving the cylinder. This will be true for VIPR acetylene cylinders, as well as the older style cylinders. The net heat of combustion for acetone is somewhat less than it is for acetylene, leading to a reduction in flame temperature, and a change in flame characteristics. The effect of acetone dilution may appear to be more noticeable when using the VIPR cylinders, possibly as a result of differences in regulator design, which might consequently work with a lower cylinder pressure, allowing more acetone into the gas mixture.

 

[premmington]

Are these Linde bottles you are using...?