Selecting the right lens shade for welding
The welding arc should never be observed at close quarters with unprotected eyes. Failure to observe this rule can result in various degrees of eye burn. These burns do not usually cause permanent injury, but they can be very painful for several days after exposure.
A helmet-type head shield, as shown in the below Figure is standard equipment for protecting the welder’s face and eyes from the direct rays of the arc. These shields are generally made from a nonflammable insulating material and are black or gray in color to minimizes reflection. They are shaped to protect the face, neck, and ears from direct radiant
energy from the arc.
What are the acceptable lens shade numbers for arc welding?
The shields are equipped with a standard-size (2x 4-l/4-in.) glass window through which the welder observes the work in the area of the arc. A proper glass lens screens almost 100% of infrared and ultraviolet rays and most of the visible rays from the welder’s eyes. The lens should be made from a tempered glass, free from bubbles, waves, or other flaws. Except for lenses that are ground for correction of vision, their flat surfaces should be smooth and parallel.
A piece of ordinary colored glass may look like a welding lens, but it would not have the necessary light-screening characteristics needed for eye protection. Special equipment is required to measure the amount of infrared and ultraviolet rays a lens will absorb. Welding lenses should be purchased only from suppliers who can be depended upon to furnish quality products.
Welding lens shades number are listed from Number 4 to number 14 in AWS Z49.1.Lens shade number 4 to 8 are useful for low light intensity welding & cutting activities such as gas cutting, brazing or soldering etc.
Lens shade chart for welding
Lenses are available in a number of shades for various types of work. Recommended shade numbers for common welding and cutting operations are listed in below Table (from ANSI Z 49.1, welding safety). Note that the shade number varies with the electrode-size range in shielded metal-arc welding and with the thickness range of material when oxygen cutting.
What shade lenses are acceptable for most types of welding?
You can easily choose welding lens shade with the above chart. As you can notice, shade number depends on:
- welding process
- Welding current
- Intensity of light produced by the welding or cutting process
For example, a gas cutting will require usually a lens shade of 4 to 8 number while gouging by air carbon requires a higher number of lens shade, usually 12 to 14 number.
What do welding shade number means?
Welding lens shades number are listed from Number 4 to number 14 in AWS Z49.1.Lens shade number 4 to 8 are useful for low light intensity welding & cutting activities such as gas cutting, brazing or soldering etc. For gas welding or oxyfuel torch welding, lens shade of 4 to 6 are suited well. For stick welding, 8 to 10 number is good. High light intensity welding processes such as plasma arc welding require high number, usually 12 to 14 shade.
Remember, as the number of the lens shade increase, the filter lens become more darker.
Glass lens shade for Gas welding and Gas cutting
For gas welding or oxyfuel torch welding, lens shade of 4 to 6 are suited well. For oxyfuel gas cutting, gas lens depends on material thickness to be cut and same for OFW Welding where thickness to be welded decide the lens shade. Below table gives details on recommended gas filter shade number for gas welding and oxygen cutting process.