Masks "flashing" with gas lens...?

[longrod]

Can anyone help me with this little problem?

I have been trying to use a gas lens but it seems to be causing problems for my masks (I have the same problem occurring with two different makes of auto-darkening filter).

The problem is that when running a weld, the filters intermittently switch from dark to light and back again, this happens for random lengths of time, (as though the weld current isn’t quite enough to switch the filter on).

This ONLY happens when I fit the gas lens, if I leave the weld current the same and swap the gas lens for the ordinary collet, everything is OK…

It occurred to me that I may need to adjust the Argon flow rate with the gas lens, I usually run about 8 litres / min, which is about 17 cu.ft / hr…?


Please help, as my eyes are getting a bit sore.

Thanks in advance.

 

[voipio]

Two possibilities spring to mind: 1) The gas lens may be shielding the light from the arc so it doesn't illuminate the sensor sufficiently well to keep it dark; 2) the gas lens has made the arc very stable.

These auto-darkening helmets require the light source to vary in intensity quite rapidly to stay dark, and if it varies little or not at all, the helmet's lens will revert to it's light state. A good test of this is to point the helmet at the sun or a halogen lamp (whilst not looking at the sun) and observing the darkness of the lens. It will normally turn light after a short while. Waving a hand across the lens will cause it to darken again as the shadow of your fingers passes over the sensors. If it's possible to introduce a bit of ripple into the welding current, by setting the base and pulse currents to slightly different values, and setting pulse frequency to say 20Hz, then that may solve the problem. Make sure pulse mode is enabled.

 

[Seano]

Or you could use a Pyrex glass gas lens, HERE that way the arc is always visible to the sensors.....

 

[longrod]

The pulsing thing seems to make sense, I'll try that later.
Do you know of any UK suppliers of the Pyrex lenses, they do look rather sexy...?

Thanks for the help.

 

[Seano]

The pulsing thing seems to make sense, I'll try that later.
Do you know of any UK suppliers of the Pyrex lenses, they do look rather sexy...?

Thanks for the help.

The only suppliers I can find really are HERE and HERE Have you though of placing more light directly on the job itself, therefore giving you a steady constant light coverage.....What torch are you using....?

 

[longrod]

Torch is an aftermarket WP-17, 1.6mm tungsten, No.7 cup.

 

[hotrodder]

CK Worldwide do pyrex cups, but you'd need to change to their collet bodies/gas lens collet bodies Rapidwelding are the UK agents

Before you spend any money try simply extending the tungsten stick out as a test first. My money's on the bulkier gas lens ceramic tipping a marginal lens over the edge so to speak. Masks vary in what they react to... an old one of mine reacted to visible light, my Speedglas doesn't. A bright sunny day, waving things across it, looking at a lightbulb etc won't do anything. Activate the HF with the torch held in mid air and it'll darken though despite the fact that nothing happens that's visible to the naked eye. LCD screens and IR remotes will also make it darken. Apparently they can get confused by the beacon on forklifts though

 

[longrod]

The pulse thing worked, and it worked on quite high frequencies as well.
Looks like its all down to the mask filter. Interesting discussion though.
I'll give the UK webiste a look and do a bit of thinking.
All the help appreciated, thanks again.