Henny Penny 500 Service Manual page 36

Model500/600/561
Safety Relief Valve Ring
This ring IS NOT to be pulled.
Severe bums will result.
and is opened automatically by the
timer at the end of the frying cycle. If this valve should become dirty
or the teflon seat nicked, pressure will not build up and it must be
repaired per the maintenance section.
drain the shortening from the cookpot into the filter drain pan.
DO NOT OPEN THE DRAIN VALVE WHILE
COOKPOT IS UNDER PRESSURE. Hot shortening will
exhaust from this valve, and severe bums will result.
Drain Interlock Switch
Amicroswitch, providing protection for the cookpot in the event an