Pressure of the atomizing gas: The pressure of the atomizing gas determines its
volume-flow-rate and thereby its velocity in the nozzle region. The maximum gas
pressure that can be used is limited by the laboratory’s air compressor unit
(Airtower26, KAESER). The minimum gas pressure is restricted by the stability of
the spray system. Overall, the gas pressure in the ValuArc 200 spray system can be
varied between 20 psig (239 kPa) and 65 psig (550 kPa).
Voltage applied on the wires: The applied voltage in the ValuArc 200 spraying
system can be varied from 20 V to 40 V.
Volume-flow-rate of the atomizing gas and its pressure were measured using the external
flow-meter (MEM Thru View, Meter Equipment Manufacturing, Inc., OH) and pressure gauge
installed between the flow-meter and the gun. These measurements are plotted in Figure 2.13 for
air as the atomizing gas. It can be observed that volume-flow-rate increases linearly with
pressure. Since the arcing occurs downstream of the nozzle, this relationship is not significantly
affected by other operating parameters (i.e. voltage, wfr, wire material).