Emerson Fisher™ 377 Trip Valve

Fisher™ 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 Bettis™ G

Series piston actuators.

Features

• 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.

• Ease of Mode Conversion—Conversion to any of the

fail modes requires only minor hookup changes.

• Adjustable Trip Valve—The trip point is adjustable

for specific supply pressure requirements.

• Reliable Operation—The trip valve design includes

large diaphragm areas and few moving parts for

efficient performance, minimum maintenance, and

long service life.

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