Download Emerson ACE97 Instruction Manual

Type ACE97
LOADING PRESSURE
EXHAUSTED BACK TO TANK
URE
SSURE
C PRESSURE
SSURE
E PRESSURE
Y PRESSURE
E BLEED PRESSURE
ON PRESSURE
SSURE
URE
SSURE
URE
URE
SURE
DEPAD PILOT
CONTROLLED
PRESSURE
RANGE SPRING
REGULATOR
NG PRESSURE
R PRESSURE
PRESSURE
RE
ON/OFF
DIAGNOSTIC
GAUGE
DEPAD
MAIN
VALVE
Vent
POPPET
VENT
ACTUATOR
CAGE
O-RING
SEAT
INLET
ROLLING
DIAPHRAGM
SENSING
CONNECTION
CLOSED PILOT
DIAGNOSTIC
PORT
MAIN
VALVE
SPRING
E0004
INLET PRESSURE
ATMOSPHERIC PRESSURE
TANK PRESSURE
INERT GAS IN
PAD VALVE
TANK
CONNECTION
PILOT LOADING PRESSURE
VENT HEADER PRESSURE
Figure 3. Type ACE97 Pad Off / Depad On
Product Description
Principle of Operation
The Type ACE97 Pad-Depad valve is a self-contained,
pilot-operated valve that maintains a blanket of inert gas
on top of a stored product to protect it from atmospheric
contamination. It reduces combustibility, decreases
vaporization, controls vapor space pressure during
pump-in and pump-out operations, and prevents the
tank from entering a vacuum condition and collapsing
upon itself. The Type ACE97 valve provides excellent
and accurate pressure control of the vapor space in the
tank. Blanketing pressure is kept to a minimum in order
to conserve the use of blanketing gas.
Type ACE97 pilot-operated valves (except for the
NPS 1/2 / DN 15 pad valve) control the vapor space
pressure over a stored liquid. The unit is stainless
steel and is controlled by a very large actuator
diaphragm. The oversized actuator diaphragm
offers high sensitivity to changes in tank pressure.
When a storage tank cools and tank vapors condense,
Type ACE97 pad (tank blanketing) valves replace the
condensing vapors with an inert gas to prevent internal
tank pressure from decreasing. Positive tank pressure
prevents outside air from contaminating the product
and reduces the possibility of atmospheric pressure
collapsing the tank.
Pad (tank blanketing) is used to describe the process
of replacing the vapor space of a storage tank with
an inert gas.
Depad (vapor recovery) is used to describe the
process of relieving or venting the vapor space as
a result of pressure rise.
Tank and vapor recovery connections are available
to meet most customer requirements. A Single Array
Manifold (S.A.M) provides a single tank and sensing
connection and is required for tanks having a single
nozzle. Accessories include gauges, purge meters,
pressure switches, and check valves.
4
Additionally, Type ACE97 valves provide depad (vapor
recovery) capabilities through the depad main valve
and depad pilot valve. When the temperature outside
the tank rises causing the vapor inside the tank to
expand, Type ACE97 depad valve vents the excess
tank pressure to a safe place.