Publicité
RP471A PNEUMATIC SNAP-ACTING RELAY
CONNECT
1/4 IN.
(6 MM)
PLASTIC
CONNECT
1/4 IN.
(6 MM)
COPPER
Fig. 3. Adaptation piping.
Port Identification Table
The right column in Table 1 identifies the ports of older
Honeywell pneumatic relays when upgrading the
installation.
Table 1. Pneumatic Relay Ports.
Pilot
Common
Normally connected
Normally disconnected
Checkout and Test
Decrease pilot pressure (port 3) to 1 psi (7 kPa) below
setpoint. This connects port 7 (Common) with port 6
(Normally Connected) and blocks port 8 (Normally
Disconnected). See Fig. 4.
Increase pilot pressure to setpoint. This connects port 7
with port 8, and blocks port 6.
6
8
7
PRESSURE DECREASE
TO SETPOINT MINUS
DIFFERENTIAL
Fig. 4. RP471A internal port alignment.
95-7252EF
POST FOR
5/32 IN. (4 MM) O.D.
PLASTIC TUBING
5/32 IN. (4 MM)
O.D. PLASTIC
TUBING CUT
TO LENGTH
5/32 IN. X 1/4 IN.
(4 MM X 6 MM)
O.D. PLASTIC
CONNECTOR
(CCTI606B)
1/4 IN. (6 MM)
O.D. PLASTIC
TUBING CUT TO
LENGTH
1/4 IN. (4 MM) O.D.
PLASTIC/COPPER
ADAPTER
(CCTI633BT)
1/4 IN. (6 MM) O.D.
COPPER TUBING
C8242
RP471A
RO49A
3
1
7
3
6
4
8
2
6
8
7
PRESSURE INCREASE
TO SETPOINT
C8243
ENGINEERING DATA
Specifications
Model: RP471A Snap-Acting Pneumatic Relay
Operating Pressure (Switch and Pilot) Range:
Normal: 0 to 18 psi (0 to 124 kPa)
Maximum Safe: 30 psi (207 kPa)
Ambient Operating Limits:
Temperature: 0 to 140°F (-18 to 60°C)
Relative Humidity: 5 to 95%
Setpoint: 3 to 15 psi (21 to 103 kPa) (field adjustable)
Differential: Between 0.1 and 0.8 psi (0.7 and 5.5
kPa), 41 to 140°F (5 to 60°C), nonadjustable; fac-
tory set
Action: SPDT, positive snap acting
Knob Rotation: 300 degrees (from 3 to 15 psi [21 to 103
kPa] on scale)
Switching Differential: 1 psi (7 kPa), with actual
operation at 0.3 to 0.4 psi (2 to 3 kPa), nonadjustable.
Air Consumption: 0.002 scfm (1.0 l/sec)
Air Handling Capacity: 0.039 scfm at 1 psi (18 ml/s at 7
kPa) differential
Construction: Molded plastic with neoprene
diaphragms, steel spring, aluminum shaft, stainless steel
lever
Operation
The return spring has an equivalent pressure of less than
1 psi (7 kPa.). See Fig. 5. The pilot pressure at port 3
must equal or exceed the switching pressure developed
by the setpoint spring. At that point, the control chamber
port opens. Pilot pressure enters the control chamber
and pushes up the control chamber diaphragm. This
opens port 8 and closes port 6.
When pilot pressure drops below setpoint minus the
differential, the setpoint spring relaxes and closes the
control chamber port. Air trapped in the control chamber
bleeds to the atmosphere.
VENT
SPRING
RETURN
COMMON
7
PILOT
3
SPRING
SETPOINT
A
Fig. 5. RP471A operation.
When control chamber pressure is less than return
spring pressure, it connects port 6 to port 7 and port 8
closes port 3 is the pilot port. See Fig. 6.
2
RP471A
NORMALLY
6
CONNECTED
8
NORMALLY
8
DISCONNECTED
6
VENT SMALL BLEED
(40 TO 60 SCCM)
CONTROL CHAMBER
CONTROL CHAMBER PORT
PILOT CHAMBER
VENT
7
3
C8245
Publicité
