The dotted line from the earth to the moon represents your line of sight when looking at the moon. The large moon image shows what you would see at that point in the cycle. For the waning gibbous, third quarter, and waning crescent phases you have to mentally turn yourself upside down when imagining the line of sight.
Where can I find some general guideline for welding ventilation? For processes such as welding, brazing, soldering, and torch cutting, the primary purpose of ventilation is to remove air contaminants from the worker's breathing zone. Different ventilation strategies may be needed in each case to remove air contaminants from the welder's breathing zone. General guidelines have been published in CSA W117.2 Safety in Welding, Cutting, and Allied Processes, and ANSI Z49.1 Standard Safety in Welding and Cutting.
TIG Welding. TIG Welding, also known as Gas Tungsten Arc Welding (GTAW), is a process that joins metals by heating them with an arc between a tungsten electrode (non-consumable) and the work piece.The process is used with a shielding gas and may also be used with or without the addition of filler metal.The primary variables in TIG Welding are arc voltage (arc length), welding current, travel speed and shielding gas composition. The amount of energy the arc produces is proportional to the current and the voltage.IG Welding. TIG Welding, also known as Gas Tungsten Arc Welding (GTAW), is a process that joins metals by heating them with an arc between a tungsten electrode (non-consumable) and the work piece.