Dehydration is readily ac c om p lished at room temperat ures. Use of a cold trap (Figure 29)
may substantially reduc e the time required to compl ete the dehydration. The high er the room
temperature, the fast er de hydration takes place. At low room temperatures , a very deep
vacuum is required for boi ling off any moisture. If low ambient temperature s are inv o lved,
contact a qualified ser v ic e representative for th e deh ydration technique s re qui red.
Perform dehydration as follows:
1. Connect a high capa city vacuum pump (5 cfm [ .002 m 3/s] or larger is recommended) to the
refrigerant chargin g valve (Figure 2A or Figure 2B). Tubing from the pump to the machine
should be as short and as lar ge a diameter as possible to pr ov i de least resistance to ga s
flow.
2. Use an absolute press ur e m an ometer or a wet bulb vacuum ind icator to measure the
vacuum. Open the shutoff valve to the vacuum indica tor only when tak ing a reading. Le ave
the valve open for 3 minut es t o allow the indicator vac uum t o equalize with the mach ine
vacuum.
Do not start or megohm t est t h e compressor motor or oil pu mp motor, even for a
rotation check, if the machine is under dehydration vacuum. Insulation break-
down and severe damage may result.
WARNING !WARNING