Taylor-Wharton EF-1500 - Manual (Page 10)

BT-481 REV. B
10
Pressure Building Circuit
The pressure building circuit serves to build pressure after filling the vessel. The circuit is also used to ensure sufficient
driving pressure during high product withdrawal periods. Opening the pressure building outlet valve (V-6) and pressure
building inlet valve (V-7) permits the circuit to function. When the pressure inside the vessel drops below the pressure
builder setting, the pressure building regulator (PCV-1) opens. This creates a path from the liquid in the bottom of the
container to the gas space in the top. This path contains an external pressure building coil (PBC-1) to vaporize product as
it flows from the bottom to the top of the vessel. Liquid is expanded to a vapor and pressure is increased in the vessel.
Figure 4: Pressure building circuit highlighted in blue.
When the EF cylinder is placed in Carbon Dioxide service and ambient temperatures are low, an electric heating system
may be required to assist in pressure building. The electric system consists of a heater in the container that is controlled
by a pressure switch in the top of the unit. The pressure switch responds to inner container pressure and turns the heater
current on and off as required to maintain a pressure greater than 125 psi (8.6 bar/862kPa). The following procedures
detail adjustment of the set points (high and low) of the pressure switch.
Field Adjustment Procedure: The set-point of the pressure switch that controls the heater element can be adjusted from
inside the control box located on the top of the container. It is factory set to 125 psi. A ¼” open end wrench is required.
V-7
PCV-1
PBC-1
V-6
SV-4
HEATER INSTALLATION :
Make sure the container vessel is at 0
psi. Open the vent valve as a
precaution. Remove the ¾” plug in the
top flange and attach adapter then insert
the heater. Be sure to use tephlon tape
on all pipe threads and seal off well
assembly with a RTV sealant. Wire the
heater to the control box according to
the schematic provided on page 11. The
heater bracket will need to be welded to
the outer head in a suitable area.