Taylor-Wharton High Capacity GST Storage Tanks - Manual (Page 8)

8
FILL
The tank is filled with liquid through the FILL CONNECTION, FILL LINE CHECK VALVE,
and FILL VALVES. One FILL VALVE is connected to the top of the pressure vessel and other
is connected to the bottom of the of the pressure vessel. Filling through the TOP FILL VALVE
tends to reduce tank pressure, while filling through the BOTTOM FILL VALVE tends to
increase tank pressure.
TANK BLOWDOWN VALVE can be opened for venting and throttled to maintain desired tank
pressure during filling.
FILL LINE CHECK VALVE prevents flow out of the tank through the fill connection in the event
of a misconnection or broken line.
FILL LINE DRAIN VALVE is used to vent the fill line during fill hose cool-down, and to drain
liquid product trapped between the fill connection and the fill valves after a fill is completed.
THERMAL EXPANSION RELIEF VALVE will relieve pressure in the fill line that may result
from expanding residual liquid trapped between the FILL LINE CHECK VALVE and the
BOTTOM and TOP FILL VALVES.
The TRYCOCK VALVE is used to determine fill termination.
WITHDRAWAL AND ECONOMIZER
During operation when the tank pressure is below the set point of ECONOMIZER BACK
PRESSURE REGULATOR liquid product is withdrawn through the siphon withdrawal line and
PRODUCT SUPPLY VALVE. When tank pressure exceeds the set point of ECONOMIZER
BACKPRESSURE REGULATOR, and ISOLATION VALVES are open gas will flow from the
top of the tank through PRESSURE BUILDING ISOLATION VALVE, ECONMOMIZER
ISOLATION VALVE, and ECONOMIZER REGULATOR. From BACK PRESSURE
REGULATOR the gas flows back in the annular space economizer line that connects to the
siphon withdrawal line, and finally exits through PRODUCT SUPPLY VALVE. When installed
external vaporizers are normally connected to PRODUCT SUPPLY VALVE.
AUXILIARY LIQUID WITHDRAWAL CONNECTION and AUXILIARY LIQUID LINE
provide liquid only withdrawal from the tank.
VAPOR LINE is the point where vapor product can be returned to the tank from a pump.
The THERMAL EXPANSION RELIEF VALVE will relieve pressure buildup from trapped
product between ECONOMIZER ISOLATION VALVE and ECONOMIZER BACK PRESSURE
REGULATOR.
PRESSURE BUILDING
The pressure building system provides a means of maintaining tank pressure at a preset value
during product withdrawal. This system operates when PRESSURE BUILDING ISOLATION