A purge cycle can be initiated in two ways; by the application of external power after a power shutdown or by an
alarm signal from the gas detector system.
When external power is first applied at connector J1, the power required for a purge cycle is supplied ahead of the
Main Circuit Breaker A1CB1. A1CB1 is held open by power control relay A1K1. This prevents power from
being applied to any equipment or lighting in the Supplemental Petroleum Laboratory until the purge cycle is
completed. Relay A1K1 supplies power to start the 5-minute time delay relay A3K1 and to energize the two
blower control relays (A3K2 and A3K5) which provide power to the ECU blowers. Power is also routed to the
purge door damper motors and to the ventilation damper motors so that the purge door dampers are opened and
the ventilation dampers are closed. The ECU blowers move outside air into the ECU ducting creating pressure
which forces any gases or contaminated air outside via the purge exhaust doors. After 5 minutes have elapsed,
time delay relay A3K1 de-energizes. This causes power control relay A1K1 to de-energize relays A3K2 and
A3K5. Power is removed from the ECU blowers, the dampers are driven to their normal positions and the Main
Circuit Breaker may now be closed to supply normal power to the Supplemental Petroleum Laboratory. If at the
end of the purge cycle the gas detector alarm system is in an alarm condition, the time delay relay is activated
causing the cycle to be repeated. This will continue until the alarm clears. If when power is applied at connector
J1 and a purge cycle initiated, and one of the external purge doors is closed, the purge alarm buzzer will be
activated by the purge door limit switch and will remain activated until the door is opened.
Water System (Refer to Figure 1-7). The water system consists of the water pump, pressure switch, water tank,
water surge tank, filter, water chiller, water heater and associated piping and valves. The water pump operates
on 110V, 60 Hz, single-phase power supplied by A15CB8 located in POWER PANEL NO. 2 and is controlled
by the pressure switch. The water pump turns on when a water outlet is opened and off when the outlets are all
closed. The water surge tank removes oscillations from the system while the water tank acts as the system
supply source. The water cooler operates on 110V, 60 Hz, single-phase power supplied by A15CB7 located in
POWER PANEL NO. 2. The water heater operates on 110V, 60 Hz, single-phase power supplied by A1CB17
located in MAIN POWER PANEL A1. The system may be supplied with water from an outside pressurized
source, from an outside unpressurized source, by using the system pump, or by its own water tank. Water
supply piping and valves are color coded blue. Water return piping and valves are color coded white. Drain
piping is colored black. Water supply valves are located at the distillation unit, the sink (both hot and cold), the
laboratory oven, the viscosity bath, and the fume hood. Water return valves are located at the laboratory oven,
the viscosity bath, and the fume hood.
Air System (Refer to Figure 1-7). The air system consists of the air compressor, air tank, pressure switch,
moisture trap, and associated piping and valves. The air compressor, located in the mechanical room, operates
on 208V, 60Hz, 3-phase power supplied from A15CB6 located in POWER PANEL NO. 2 and can supply air at
120 psi to the system. In automatic operation, the compressor is controlled by a pressure switch which shuts it
off when the pressure has reached 120 psi and turns it back on when the pressure in the system drops to 60 psi.
The air tank relief valve is set to operate at 150 psi. Air piping is color coded green and valves are color coded
orange. Air supply valves are located next to the distillation unit, behind the viscosity bath, in the fume hood,
and forward of the muffle furnace.
Vacuum System (Refer to Figure 1-7). The vacuum system consists of the vacuum pump and associated piping
and valves. The vacuum pump is located in the mechanical room and operates on 110V, 60Hz, single-phase
power supplied from A15CB9 located in POWER PANEL NO. 2. It has a free air capacity of 58 liters per
minute and supplies vacuum where required. Vacuum piping and valves are color coded yellow. Vacuum
supply valves are located behind the viscosity baths, in the fume hood, and forward of the muffle furnace.
Water Still. The water still is electrically operated and supplies pure water for use in the laboratory. Located on
the curbside wall it operates on 110V, 60Hz, single-phase power supplied from a convenience outlet.