Manual Reset Operation - Johnson Controls P70 Manual

Limited Knob Adjustment
Some models are supplied with a Limited Knob
Adjustment kit, which limits adjustments to the
pressure control and help to deter over-adjustment or
tampering.
To lock the differential setting and allow limited
adjustment of the low event and high event setpoints,
install the knob on the range screw.
To lock the high event setpoint and allow limited
adjustment of the low event setpoint (on All-Range
controls) or differential setting (on MICRO-SET
controls), install the knob on the differential screw.
To install the Limited Knob Adjustment: kit:
1. Adjust control pointers to desired high event and
low event setpoints (on All-Range controls), or
differential setting (on MICRO-SET controls).
2. Place spacer on the proper adjustment screw.
•
All-Range controls (with Limited Knob
Adjustment kit ) have round and knurled
adjustment screws—the spacer must always
be placed on the range screw.
•
MICRO-SET controls have square adjustment
screws, always place the spacer on the same
adjustment screw as the knob.
3. Place the indicator plate as shown in Figure 10, to
lock either the range screw or differential screw in
the desired setting.
4. Install the knob on the other adjustment screw,
and tighten the setscrew. A stop on the bottom of
the knob limits screw adjustment to less than one
turn.
IMPORTANT: Use the pressure control settings
recommended by the manufacturer
of the controlled equipment. Do not
exceed the pressure ratings of the
controlled equipment or any of its
components when checking
pressure control operation or
operating the controlled equipment.
IMPORTANT: After installing and adjusting
pressure control, and before
leaving installation, cycle the
controlled equipment several times
(at least three) at normal operating
conditions. Use reliable pressure
gauges to verify proper control
settings and equipment operation.
8 P—P70, P72, and P170 Controls for Low Pressure Applications Product/Technical Bulletin
Adjustment Knob with Set Screw
Range Screw
Installation of Knob Kit to
Lock Differential Screw and
Allow Limited Adjustment of
Range Screw
*On MICRO-SET controls, place spacer on same adjustment
screw as knob.
On All-Range controls, always place spacer on range screw.
Figure 10: Installing Limited Knob Adjustment Kit

Manual Reset Operation

Pressure controls with the Manual Reset option, lock
out when they reach cut out pressure and must be
manually reset by the user to restart the controlled
equipment. The manual reset mechanism is "trip-free"
and cannot be over-ridden by blocking or tying the
reset button down.
On equipment with locked out controls, first determine
and remedy the cause of the lockout, and allow the
sensed pressure to return to the cut-in setpoint. Then,
press and release the reset button on the front of the
control to restore operation of the controlled
equipment.
Indicator Plate
Spacer*
Range Screw
Differential Screw
Installation of Knob Kit to
Lock Range Crew, and
Allow Limited Adjustment of
Differential Screw