AWS F1.2:2013 pdf download.Laboratory Method for Measuring Fume Generation Rates and Total Fume Emission of Welding and Allied Processes
4.1 General Description of Suggested Chamber
The conical test chamber (Figure 1) is fabricated with holes to allow manual access into the chamber. A sighting window with an appropriate removable shaded lens is located in the center of the chamber to provide visibility for setting up and observing tests. Leveling bolts are provided to maintain an air gap of about 1/2 in to 3/4 in(13 mm to 19 mm) between the base of the chamber and the surface on which it rests. A filter assembly for collecting the fumes, consisting of the fil-ter and its supports, a pressure drop gauge, and a constant flow rate pump, is mounted at the top of the chamber. This arrangement makes the filter accessible for quick and easy changes.
5. Preliminary Setup
5.1 Automatic, semiautomatic, or manual processes may be used for the test. If an automatic setup is desired, some means of plate movement is necessary beneath the positioned welding gun. A turntable that rotates a plate within the chamber is suggested (Figure 2). A torch can be positioned so that it enters the chamber through one of the hand holes and is held at the appropriate contact tip-to-work distance. For semiautomatic or manual processes, the operator may insert an arm(s) through the inlets provided with snugly ftting rubber closures and weld on a plate within the chamber.
5.2 To obtain repeatable, accurate results, careful attention must be paid to maintaining applicable variables constant,such as contact tip-to-work distance, travel angle, and arc voltage during the test. These have a significant influence on the amount of fume generated (see Annex A for further details).
6.3 If the test results are not compliant when compared to the values in Table 1, check to ensure that visible amounts of fume are not escaping from the test chamber during welding. Also check that the wire feeder setting of WFS and voltage are accurate. If the contact tip-to-work distance has been accurately measured and remained constant during welding,then the current reading should be as noted above. If the current reads substantially lower, the contact tip may be fouled and contact may be occurring too far upstream, the wire diameter may be undersized, and/or the actual WFS may be lower than the indicated value. If the current reads too high, the wire diameter may be oversized and/or the actual WFS may be higher than the indicated value. Voltage is not a point function; it is a measure of the power difference between two points of the welding electrical circuit. Ideally.AWS F1.2 pdf download.