Johnson Controls Penn P70 Series Product/Technical Bulletin page 6

L1
Low
Alarm
2
1
3
Low
Low side switch opens
1 to 2 and closes 1 to 3
on pressure drop.
Figure 8: Two SPDT Switches Wired as a Dual
Pressure Control (Switching a Single Load with
Optional High Side Alarm and Low Side Alarm)
(P70S and P170S Models)
L1
L2
1
High side switch opens
1 to 2 and closes 1 to 3
on pressure rise.
1
Low side switch opens
1 to 2 and closes 1 to 3
on pressure drop.
Figure 9: Two SPDT Switches Wired to
Control Two Different Loads, (Optional High Side
Alarm and Low Side Alarm)
(P70S and P170S Models)
A
djustments
Adjustment of the P70, P72, and P170 dual pressure
controls varies, depending on the model. The following
guidelines and diagrams illustrate the procedures for
adjusting these controls. Refer to the product label
inside the control cover for model number and switch
action, and check the front of the control cover to
determine if the control is All-Range or MICRO-SET.
6 P—P70, P72, and P170 Controls for Dual Pressure Applications Product/Technical Bulletin
High
Alarm
Load
3
1
2
High
High side switch opens
1 to 2 and closes 1 to 3
on pressure rise.
High High
Alarm
Load
3
2
Low
Low
High
Load Alarm
2
3
Low
All-Range Controls (Low Side Only)
The low side of All-Range pressure controls has a
scaleplate that displays the CUT IN and CUT OUT
setpoints. (See visible scale on left side of control.)
Turning the range screw adjusts the CUT IN and
CUT OUT setpoints up or down simultaneously, while
maintaining a constant pressure differential. Turning
the differential screw adjusts the CUT OUT setpoint
only on the left side of the scale, and changes the
pressure differential.
MICRO-SET Controls (Low Side Only)
The low side of MICRO-SET pressure controls has a
scaleplate that displays the CUT IN setpoint and
DIFFERENTIAL setting. (See visible scale on left side
of control.) Turning the range screw adjusts the
CUT IN setpoint on the right side of the scale. Turning
the differential screw adjusts the DIFFERENTIAL
setting on the left side, which changes the resulting
CUT OUT pressure.
High Side—Dual Pressure Controls
The high side of the P70, P72, and P170 dual
pressure controls has a scaleplate that displays only
the CUT OUT setpoint. (See the visible scale on right
side of control.) Turning the range screw adjusts the
CUT OUT setpoint. The differential is fixed at
approximately 65 psi.
For controls with the high side (or combination low
side and high side) Manual Reset Lockout option, see
Manual Reset Operation.
For P70S and P170S controls, see Convertible High
Pressure Reset Mechanism on P70S and P170S
Controls.
IMPORTANT: Do not adjust pointers beyond
the highest or lowest indicator
marks on the control's pressure
scale. Adjusting pointers beyond
indicator marks may damage
screw threads and cause
inaccurate control operation.