color=black>Yahoo! is not affiliated with the authors of this page or responsible for its content.
377 Series Trip Valves www.Fisher.com
D200318X012
377 Series Trip Valves
The 377 Series pressure-sensing trip valves (see
figures 1 and 2) are for control applications where a
specific valve/actuator action is required when
supply pressure falls below a specific point. When
supply pressure falls below the trip point (see figure
3), the trip valve causes the actuator to fail up, lock
in the last position, or fail down. When the supply
pressure rises above the trip point, the 377 Series
trip valve automatically resets, allowing the system
to return to normal operation. The trip valve can be
top-mounted on a manifold, yoke-mounted, or
bracket-mounted to match the application
requirements. The 377 Series trip valves can be
used with 480, 585C, 1061, 1066, 1069, and G
Series piston actuators.
Features
D Cost EffectiveSingle trip valve construction
reduces costs and spare part requirements of those
systems using three separate switching valves to
perform the failure functions. A single trip valve
greatly simplifies piping requirements.
D Ease of Mode ConversionConversion to
any of the fail modes requires only minor hookup
changes.
D Adjustable Trip ValveThe trip point is
adjustable for specific supply pressure requirements.
D Reliable OperationThe trip valve design
includes large diaphragm areas and few moving
parts for efficient performance, minimum
maintenance, and long service life.
W4292-1/IL
Figure 1. 377 Series Trip Valve
W8435-1
Figure 2. Type 377 Trip Valve Mounted on Size 130 Type
585C Actuator
Product Bulletin
62.3:377
May 2006
377 Trip Valve 377 Trip Valve
Product Bulletin
62.3:377
May 2006
2
Specifications
Available Configurations
When supply pressure falls below the trip point,
Type 377D Trip Valve: Fails actuator piston
down. Includes check valve and volume tank
Type 377L Trip Valve: Locks actuator piston in
the last position
Type 377U Trip Valve: Fails actuator piston up.
Includes check valve and volume tank.
Type 377CW Trip Valve: Fails fully clockwise to
close the valve. Requires check valve and volume
tank. Trip valve moves piston to either up/down
position and requires actuator configuration for
actual clockwise movement.
Type 377CCW Trip Valve:
Fails fully
counterclockwise to close the valve. Requires
check valve and volume tank. Trip valve moves
piston to either up/down position and requires
actuator configuration for actual counterclockwise
movement.
All 377 Series Trip Valves can be converted to
any of the above fail modes with minor hookup
changes
Allowable Supply Pressure for Trip Valve
(1)
Maximum: 10.3 bar (150 psig)
Minimum: 3.8 bar (55 psig)
Outlet Pressure
(1)
Normal Operation: Pressure from control device
Fail-Up or Fail-Down Mode: Maximum volume
tank pressure
Lock-In-Last-Position: Respective cylinder
pressure
Trip Point
(2)
Adjustable from a minimum of 2.8 bar (40 psig) to
a maximum of 72 percent of supply pressure; see
figure 3.
Reset: 12.5 to 33 percent above adjusted trip
point
Flow Coefficients (C
v
)
(3)
Depends on flow path (shown in figure 4) as
follows:
Port A to Port B: 0.47
Port B to Port C: 0.56
Port D to Port E: 0.48
Port E to Port F: 0.64
Body Connections
1/4-inch NPT female
Temperature Capabilities
(1)
Nitrile Diaphragms and O-Rings: 40 to 82°C
(40 to 180°F)
Fluoroelastomer Diaphragms and O-Rings:
18 to 104°C (0 to 220°F)
Volume Tank Maximum Internal Working
Pressure (for Type 377D, 377U, 377CW and
377CCW trip valves)
Standard: 10.3 bar (150 psig) for non-ASME
approved applications
(4)
.
ASME Approved Applications: Rated 10.3 bar
(150 psig), maximum; 9.3 bar (135 psig),
recommended
Volume Tank Sizing
See sizing section
Hazardous Area Classification
Complies with the requirements of ATEX Group II
Category 2 Gas and Dust
Mounting
Top-Mounted: Manifold-mounted between a
3570 Series positioner and 480 Series actuator
(manifolds cannot be supplied with 585C, 1061,
1066, and 1069 Series piston actuators)
Side-Mounted: Yoke-mounted or
bracket-mounted for use with a FIELDVUE
R
DVC6000 or DVC6000f Series digital valve
controller
Continued 377 Trip Valve
Product Bulletin
62.3:377
May 2006
3
Specifications (continued)
Approximate Weight
Trip Valve: 2.0 kg (4.5 pounds)
Mounting Manifold: 0.5 kg (1.2 pounds)
Volume Tank: Varies between 5.4 and 21 kg (12
and 47 pounds) depending on size
Construction Materials
Body, Spring Case, and ManifoldAluminum
Cover25% mineral-filled thermoplastic
polyester
O-Ringsnitrile or fluoroelastomer
Diaphragmsnitrile or fluoroelastomer
Interior partsbrass, aluminum, steel, and
stainless steel
1. The pressure/temperature limits in this document and any applicable standard or code limitation should not be exceeded.
2. If the trip point is not specified, the trip point is factory-set at 72 percent of supply pressure or 2.8 bar (40 psig), whichever is higher.
3. Values represent nominal C
v
measures for each port pair using a trip valve/actuator combination.
4. This tank is rated at 14.5 bar (240 psig) in LP service. When used with air, the rating should be considered to be 10.3 bar (150 psig), consistent with the maximum pressure allowed for the
377 Series trip valve.
10.3
4
5
6
7
8
9
10
110
100
90
80
70
60
50
40
7.6
7
6
5
4
3
150
140
130
120
110
100
90
80
70
60
55
NOTE:
TRIP POINT MAY BE SET TO ANY VALUE BETWEEN
2.8 BAR (40 PSIG) AND THE MAXIMUM TRIP POINT LINE.
RESET OCCURS AT 12.5 TO 33 PERCENT
ABOVE ADJUSTED TRIP POINT.
TRIP
POINT
, PSIG
TRIP
POINT
,
BAR
SUPPLY PRESSURE, BAR
SUPPLY PRESSURE, PSIG
A2779-2/IL
MAXIMUM TRIP POINT
SETTING TO ENSURE
RESET
1
1
2
2
Figure 3. Maximum Trip Point Settings
Note
Neither Emerson
R
, Emerson Process
Managementt, Fisher
R
, nor any of
their affiliated entities assumes
responsibility for the selection, use,
and maintenance of any product.
Responsibility for the selection, use,
and maintenance of any product
remains with the purchaser and
end-user.
UPPER
DIAPHRAGM
EXHAUST
PORT
RESTRICTION
PORT A
PORT B
PORT D
PORT E
PLUG
ASSEMBLIES
PORT F
PORT C
VALVE
PLUG SPRING
SUPPLY
CONNECTION
LOWER
DIAPHRAGM
W4303-1/IL
Figure 4. Simplified Sectional View of Trip Valve
Principle of Operation
Type 377D Trip Valve
In normal operation, supply pressure loads the upper
diaphragm (see figure 4) of the unit. The valve plug
spring keeps the exhaust port closed. Supply
pressure also loads the lower diaphragm through the 377 Trip Valve
Product Bulletin
62.3:377
May 2006
4
SPRING
VALVE PLUG
UPPER
DIAPHRAGM
EXHAUST
PORT
SUPPLY
PRESSURE
LOWER
DIAPHRAGM
PORT D
PORT E
LOWER
PORTS
PORT F
PORT C
PLUG
ASSEMBLIES
UPPER PORTS
PORT B
PORT A
VENT
MAIN
SPRING
ACTUATOR
CONTROL
DEVICE
CHECK
VALVE
VOLUME
TANK
Figure 5. Type 377D Trip Valve Shown Tripped
restriction, causing the plug assemblies to move
down and isolate ports C and F while connecting
port A to B and port D to E. Normal actuator control
pressure flows from the control device to the top of
the cylinder through ports A and B and to the bottom
of the cylinder through ports D and E. A volume tank
is charged to maximum supply pressure through a
check valve in order to retain maximum supply
pressure in the volume tank if supply pressure drops.
When supply pressure falls below the trip point
pressure in the fail-down mode (see figure 5), the
exhaust port opens, venting the supply pressure that
is loading the lower diaphragm. This causes the
upper ports of the plug assemblies to close and shut
off normal pressure flow from the control device to
the actuator.
Volume tank pressure then flows through ports C
and B to the top of the actuator cylinder, while
pressure in the bottom of the actuator cylinder is
vented through ports E and F. The pressure
imbalance created forces the actuator piston down.
When supply pressure is restored, it loads the upper
and lower diaphragms, causing the trip valve to
reset. The exhaust port closes. The upper ports of
the plug assemblies open, and the lower ports close.
Normal actuator control pressure flow from the
control device is restored through ports A and B and
ports D and E. The check valve opens and recharges
the volume tank to the maximum supply pressure.
Type 377L Trip Valve
When supply pressure falls below the trip point in the
lock-in-last-position mode (see figure 6), the 377 Trip Valve
Product Bulletin
62.3:377
May 2006
5
SPRING
VALVE PLUG
UPPER
DIAPHRAGM
EXHAUST
PORT
SUPPLY
PRESSURE
LOWER
DIAPHRAGM
PORT D
PORT E
LOWER
PORTS
PORT F
PORT C
PLUG ASSEMBLIES
UPPER PORTS
PORT B
PORT A
VENT
MAIN SPRING
ACTUATOR
CONTROL
DEVICE
Figure 6. Type 377L Trip Valve Shown Tripped
exhaust port opens, venting supply pressure from
the lower diaphragm. This causes the upper ports of
the plug assemblies to close and the lower ports to
open. Since ports C and F are plugged, no pressure
change occurs on either side of the actuator piston,
and the piston is pressure-locked in position upon
loss of supply pressure. No volume tank is
necessary in this mode. When supply pressure is
restored, the plug assemblies move back into the
normal operating position, and supply pressure flows
from the control device through ports A and B to the
actuator.
Type 377U Trip Valve
The fail-up mode of operation (figure 7) is similar to
the fail-down mode of operation except that
connections to port C and F are reversed. When
supply pressure falls below the trip point, the top of
the actuator cylinder vents, and volume tank
pressure loads the bottom of the actuator cylinder.
The pressure imbalance created forces the actuator
piston up.
Type 377CW and 377 CCW Trip Valves
Makes use of the 377D or 377U trip valve
configurations, a piston actuator, and volume tank
with check valve to move the piston ac