Honeywell P906C Operation manual

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P906C
Proportional
Differential Pressure Controllers
PRODUCT DATA
FEATURES
• Proportional control
• 4 – 20 mA current output
• Control range: 0 – 70 psi (0 – 483 kPa)
• Adjustable throttling range
APPLICATION
The P906C differential pressure controller
provides proportional control to maintain
the desired pressure difference between
two points in a water system. It is suitable
for use with modulating control valves to
regulate the by-pass differential pressure of
water chillers.

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P906C PROPORTIONAL DIFFERENTIAL PRESSURE CONTROLLERS
SPECIFICATIONS
Operating Pressure psi (kPa)
Model
Control
Differential
Pressure Range
psi (kPa)
Minimum Maximum
Output
P906C 0 – 70
(0 – 483) 5 (35) 225 (1551) 4 – 20 mA
Dimensions: See Fig. 1.
Electrical Ratings:
Power Supply: 220 Vac 50 Hz
Ambient Ratings:
Operating Temperature: 0 – 60 °C
Operating Humidity: 5 – 95% RH non-
condensing
Fig. 1. Dimensions of P906C in inch [mm].
INSTALLATION
When Installing this Product…
1. Read these instructions carefully.
Failure to follow them could damage the
product or cause a hazardous condition.
2. Check the ratings given in the
instructions and on the product to make
sure the product is suitable for your
application.
3. Installer must be a trained, experienced
service technician.
4. After installation is complete, check out
product operation as provided in these
instructions.
IMPORTANT
All wiring must agree with applicable
codes, ordinances and regulations.
! CAUTION
Electrical Shock or Equipment Hazard.
Can shock individuals or short
equipment circuitry.
Disconnect power supply before installation.
Location and Mounting
Mount the controller on a surface that is free
of excessive vibration. Level the control
using appropriate leveling devices.
NOTE: To prevent strain on the bellows, use
the proper fittings when connecting the
tubing or pipe to the bellows connections
(See Fig. 2). Use care when running lines so
that pipe dope and scale do not get into the
internal lines.

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P906C PROPORTIONAL DIFFERENTIAL PRESSURE CONTROLLERS
WIRING
Disconnect power supply before beginning installation to prevent electrical shock and equipment
damage. All wiring must comply with local electrical codes and ordinances. See Fig. 3 and 4 for
typical system hookup and wiring.
Fig. 2. Recommended Tubing Fittings
Fig. 4. Typical Wiring Fig. 3. Typical System Hookup
OPERATION
Pressure Difference Adjustment
Because these controllers have such a wide
variety of applications, they are adjusted on
the job with the system in operation.
IMPORTANT
The device controls the difference between
the pressures exerted upon the 2 bellows,
not the gauge pressure.
1. Connect a pressure gauge with adequate
range to each element assembly.
2. Connect the differential pressure controller
and gauges to the pressure points to be
controlled.
3. Turn the pressure difference adjustment
screw counterclockwise (↖) until the scale
indicators reach the low (minimum) end of
the scale (Fig. 5).
4. Turn the throttling range adjustment screw
until the throttling range indicator is midway
between C and D on the throttling scale
plate.
NOTE: Do not go beyond the point at which
the linkage begins to show slack.
5. Apply typical operating pressures in
sequence to the left and right elements
(high and low pressure sides,
respectively). Turn the pressure
difference adjustment screw clockwise
() until the desired differential pressure
is reached.
6. Adjust the throttling range as needed.
To increase the throttling range, turn the
throttling range adjustment screw
clockwise (). To decrease the
throttling range, turn the throttling range
adjustment screw counterclockwise (↖).
7. Apply pressures through a typical cycle
while checking the differential pressure
controller operation. Readjust settings if
necessary. If there is any indication of
short cycling or a hunting condition,
increase the throttling range setting.
8. When the system operates as desired,
mark the settings on the scaleplate.

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9. Remove the gauges and connect the
differential pressure controller into the
system with the higher pressure on the
left element and the lower pressure on
the right element.
CHECKOUT
Check operation of controller after installing in system.
Fig. 5. Internal View of the P906C Differential Pressure Controller
Honeywell Limited
25/F Honeywell Tower
Olympia Plaza
255 King’s Road
North Point, Hong Kong
0804
Pressure Difference
Adjustment Screw
Throttling Range Adjustment Screw
Throttling Range Scale Plate
Pressure
Difference
Scale Plate m
A
Out
p
ut Terminals
Power Supply
Terminals
Right Element
Assembly (Low
Pressure Side)
Left Element Assembly (High Pressure Side)