Emerson Fisher 377 Data Sheet

377 Trip Valve

D200318X012

Fisherr 377 Trip Valve

Fisher 377 pressure‐sensing trip valves 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 1), 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 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. 377 trip valves can be used with Fisher
480, 585C, 685, 1061, 1066, 1069, and Bettist G
Series piston actuators.

Product Bulletin

62.3:377

July 2014

Features

n Cost Effective—Single 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.

n Ease of Mode Conversion—Conversion to any of the

fail modes requires only minor hookup changes.

n Adjustable Trip Valve—The trip point is adjustable

for specific supply pressure requirements.

n Reliable Operation—The trip valve design includes

large diaphragm areas and few moving parts for
efficient performance, minimum maintenance, and
long service life.

W4292‐1

W8435‐1

Fisher 377 Trip Valve Mounted on

Size 130 585C Actuator

www.Fisher.com

Product Bulletin

62.3:377
July 2014

Specifications

Available Configurations

When supply pressure falls below the trip point,
377D Trip Valve: Fails actuator piston down. Includes

check valve and volume tank.
377L Trip Valve: Locks actuator piston in the last

position.
377U Trip Valve: Fails actuator piston up. Includes

check valve and volume tank.
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.

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 trip valves can be converted to any of the
above fail modes with minor hookup changes

Allowable Supply Pressure for Trip Valve

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

(1)

377 Trip Valve

D200318X012

Flow Coefficients (C

Depends on flow path (shown in figure 3) as follows:

Port A to Port B and Port D to Port E: 0.5
Port B to Port C and Port E to Port F: 0.6

Body Connections

1/4 NPT internal

Temperature Capabilities

Nitrile Diaphragms and O‐Rings: -40 to 82°C
(-40 to 180°F)
Fluorocarbon Diaphragms and O‐Rings: -18 to 104°C
(0 to 220°F)

Volume Tank Maximum Internal Working Pressure
(for 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

(3)

)

v

(1)

Trip Point

(2)

Adjustable from a minimum of 2.8 bar (40 psig) to a
maximum of 72 percent of supply pressure;
see figure 1

Reset: 12.5 to 33 percent above adjusted trip point

Table of Contents

Features 1.....................................

Safety Certification 3............................

Principle of Operation 4.........................

377D Trip Valve 4.............................

377L Trip Valve 6..............................

377U Trip Valve 7.............................

377CW and 377 CCW Trip Valves 7...............

2

377 SST

Safety Instrumented System Classification
SIL 3 capable - certified by exida Consulting LLC

-Continued-

Volume Tank Sizing 8...........................

Installation 9..................................

Ordering Information 10.........................

Application 10................................

Trip Valve 10.................................

377 Trip Valve

D200318X012

Specifications (continued)

Product Bulletin

62.3:377

July 2014

Mounting

Top‐Mounted: Manifold‐mounted between a 3570
positioner and a 480 actuator (manifolds cannot be

Mounting Manifold: 0.5 kg (1.2 pounds)
Volume Tank: Varies between 5.4 and 363 kg (12 and

800 pounds) depending on size

supplied with 585C, 685, 1061, 1066, and 1069
piston actuators)
Side‐Mounted: Yoke‐mounted or bracket‐mounted

Construction Materials

for use with a FIELDVUEt DVC6200, DVC6200f,
DVC6200p, DVC6000, or DVC6000f digital valve
controller

Housing:

J Aluminum or J Stainless steel

Cover: 25% mineral‐filled thermoplastic polyester
O‐Rings: Nitrile or fluorocarbon

Approximate Weight

Trip Valve

Aluminum: 0.95 kg (2.1 pounds)
Stainless Steel: 2.31 kg (5.1 pounds)

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

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 trip valve.

measures for each port pair using a trip valve/actuator combination.

v

Figure 1. Maximum Trip Point Settings

Diaphragms: Nitrile or fluorocarbon
Interior parts

Aluminum construction: Brass, aluminum, steel, and
stainless steel
Stainless Steel construction: Stainless steel

Safety Certification

The 377 SST is certified for use in Safety Instrumented

45 67 8 910

110

100

90

80

70

TRIP POINT, PSIG

60

50

40

A2779‐2

SUPPLY PRESSURE, BAR

2

MAXIMUM TRIP POINT
SETTING TO ENSURE
RESET

SUPPLY PRESSURE, PSIG

10.3

7.6

7

6

5

TRIP POINT, BAR

4

1

3

1501401301201101009080706055

System (SIS) applications. Certification is by exida
Consulting LLC, a global provider of functional safety
and control system security (see figure 2). SIS
certification is identified on the product by a label
affixed to the pilot body.

The functional safety assessment was performed to
the requirements of IEC 61508: ed2, 2010, SIL3 for
mechanical components.

Figure 2. exida Certificate

1 Trip point may be set to any value between 2.8 bar (40 psig) and the
maximum trip point line.
2 Reset occurs a 12.5 to 33 percent above adjusted trip point.

3

Product Bulletin

62.3:377
July 2014

377 Trip Valve

D200318X012

Principle of Operation

377D Trip Valve

In normal operation, supply pressure loads the upper
diaphragm (see figure 3) of the unit. The valve plug
spring keeps the exhaust port closed. Supply pressure
also loads the lower diaphragm through the
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.

Figure 3. Simplified Sectional View of Trip Valve

UPPER
DIAPHRAGM

VALVE
PLUG SPRING

SUPPLY
CONNECTION

LOWER
DIAPHRAGM

PORT D

PORT E

EXHAUST
PORT

RESTRICTION

PORT A

PORT B

When supply pressure falls below the trip point
pressure in the fail‐down mode (see figure 4), 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.

PLUG
ASSEMBLIES

W4303‐1

PORT F PORT C

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.

4