Honeywell SP970A Instructions D'installation page 4

SP970A, B, C AND D MANUAL AND MINIMUM POSITION PRESSURE REGULATORS
SP970C and D: Four Port Switches
These minimum position devices have a separate dead
ended chamber connected to port 3 to receive an
external signal. When the external signal is less than the
spring load, the signal has no effect and functions similar
Application
Fig. 8A shows a typical manual position application using
the three port SP970A, B. This control system manually
positions a damper between OPEN and CLOSED.
Turning the setpoint knob clockwise increases the
branchline pressure to the damper actuator and opens
the damper. Turning the position knob counterclockwise
decreases the branchline pressure and closes the
damper.
The three port SP970A, B is also used with a controller
for automatic damper positioning with minimum position.
See Fig. 8B. When the external signal is less than the
BRANCH
M
EXH
A. MANUAL POSITION
APPLICATION
Automation and Control Solutions
Honeywell
1985 Douglas Drive North
Golden Valley, MN 55422
95-7237EF J.H. Rev. 2-02
PILOT
CHAMBER
3
PILOT
BRANCH
3
4
VENT
A. BUILDING TO MINIMUM SETTING
3
PILOT
BRANCH
3
4
VENT
B. BALANCED AT MINIMUM SETTING
Fig. 7. SP970C and D operation.
DAMPER
ACTUATOR
2
1
4
M
SP970A OR B
1 2
CONTROLLER
B. MINIMUM POSITION
APPLICATION WITH
CONTROLLER INPUT
Fig. 8. Typical SP970 application.
Honeywell Limited-Honeywell Limitée
35 Dynamic Drive
Scarborough, Ontario
M1V 4Z9
to the SP970A, B as a pressure regulator. When the
external signal is greater than the spring load, the spring
load is isolated and the device duplicates the input
signal. See Fig. 7.
SP970C,D
DISC
3
PILOT
BRANCH
3
1
MAIN
C. PILOT BUILDING BRANCH ABOVE
MINIMUM SETTING
SP970C,D
3
PILOT
BRANCH
3
1
MAIN
D. BALANCED AGAINST PILOT
knob setting, the spring maintains the branchline
pressure as previously described. When the external
signal rises above the knob setting, air from the signal
flows directly to the branch. During steady state
conditions, the external automatic controller must be
capable of exhausting the air flowing through the exhaust
(pilot) port 4.
Fig. 8C shows a typical four port SP970C, D application.
The minimum position switch keeps the pneumatic
actuator at a minimum position until the thermostat
pressure is greater than the minimum position valve. The
thermostat then controls the actuator.
DAMPER
ACTUATOR
BRANCH
2
M
1
4 EXH
SP970A OR B
C. MINIMUM POSITION
Printed in U.S.A. on recycled
paper containing at least 10%
post-consumer paper fibers.
SP970C,D
4
1
VENT MAIN
SP970C,D
4 1
VENT MAIN
C4300
DAMPER
ACTUATOR
BRANCH
2
M
1
SP970C OR D
3
4
M
INSERTION
THERMOSTAT
APPLICATION
WITH THERMOSTAT
C8279
customer.honeywell.com