Data Sheet
Bulletin 74.3:ACE97
3
Figure 2. Type ACE97 Pad-Depad Valve Parts
E0673
VENT
Provides sense line connection and
main valve connection through a single tank nozzle.
Prevents corrosive tank vapors from damaging
upstream equipment.
When tank pressure decreases below the pad setpoint (due to pump
out operations or thermal cooling), the actuator diaphragm moves
downward pushing open the pad pilot. This creates ow from the
pad loading chamber to downstream. When pad loading pressure
decreases, the force created by inlet pressure on the pad main valve
plug overcomes the main spring force and opens the main valve
plug allowing ow through the pad valve to the tank. Once tank
pressure reaches pad setpoint, the pad pilot closes, pad loading
pressure equalizes with inlet pressure and the pad valve closes.
The NPS 1/2 / DN 15 Pad valve has a main valve only. When tank
pressure decreases below the pad setpoint the actuator diaphragm
moves downward pushing the valve plug open and allowing ow
through the pad valve to the tank.
When tank pressure increases above the depad setpoint (due to
pump-in operations or thermal heating), the actuator diaphragm
moves upward and pushes open the depad pilot. This releases
depad loading pressure (nitrogen or other supply gas). When depad
pilot loading pressure decreases, the depad main valve opens by a
spring and allows ow from the tank to the vent or recovery system.
Tank blanketing valves are often installed in locations that are
difficult to access. Type ACE97 valves are available with a
diagnostics feature that allows analysis of valve operation in the
field, making maintenance easier and more reliable.
The diagnostics feature relies uses relationship of pressure in
the pilot and main valve chambers to analyze valve performance.