Gas lenses cause the gas to flow straight out of the cup for a greater distance allowing you to extend you electrode out further than you would normally dare and still get good gas coverage.

Great for most jobs particularly when you are next to edge with nothing to hold the gas back.

Draw back is the base of the cups are larger and won't allow you to get in to some areas.

Tell your vendor he needs to learn more about what he is dealing in. If he has never heard of gas lenses he doesnt know his way around welding supplys. Tell him to get you catalogs from his suppliers.

Bhilts;

Ron is right! The official term would be Gas Lens/collet body. This is basic stuff that any welding sales pro should be knowledgable about.

http://content.lincolnelectric.com/pdfs/products/literature/e12150.pdf

The above link will give you a brief discription and even some pictures so that you will know exactly what one looks like.

The gas lense actually acts as a diffuser (similar to the one on your faucet in the form of a screen, or a grid on a light fixture.) While the gas does exit the nozzle in a straight pattern, the gas lense actually provides several functions such as minimizing the possibility of a vortex at the nozzle perimeter, directing the gas at the weld puddle and enhancing shielding of the electrode. Gas lenses are available for areas of tight access, but these also have their limitations because they are physically longer than a nozzle without the lense.

You will not gain anything if a gas lense is not required, in other words, why are you choosing to use these? Are you welding exotic materials? These were only used on chrome or nickel based materials where shielding was critical when I was a TIG welder working in the aerospace biz. Everything else was welded in a chamber or a bubble.

These will not do anything for you if your welding carbon steel or aluminum. You will also pay >$$ to use these in lieu of a "regular" nozzle.

shop talk 3 nov 00 to find the end of a thread on this subject.

Bill

Theres a lot of good ideas here! I'm sure that your talking about a small store that doesn't specialize in welding. Gas lenses are used in construction and other places to help minimize or eliminate porosity caused by imperfect conditions like wind. Not everyone has the luxury to work out of inclement weather and have to take advantage of everything out there for maximum coverage.