PINPOINT pH Controller USERS Manual
I. Overview
II. General Specifications
III. Displays & Adjustments
IV. pH Calibration
V. Important Note on Probe Placement
VI. Adjusting the Controller Setpoints
VII. pH Monitor Theory
I. Overview
This device consists of a pH Monitor and electronics, which control external
devices, based on the pH reading. Accordingly, there are two adjustments that
must be made to the controller before putting into service. The calibration of the
electronics which read the pH and the adjustments of the controller setpoints.
After the controller is in service, it will be necessary to re-confirm and perhaps re-
calibrate the pH monitor.
It is important that you understand these instructions and it is critical that you
follow the cautions in this manual. Most users will be controlling the addition of
CO2 into their system with this instrument and there can be disastrous results if
CO2, another acid or a base is added to the system in an uncontrolled fashion. It is
critical that one pay special attention to the placement of the pH probe in the
system. You must frequently check the condition and calibration of the pH probe.
We strongly require that you build sanity into your system. Needle valves, and
similar devices, should be designed to throttle-down the flow of gases into the
system at a reasonable rate. If a base is being added, the maximum rate of addition
should be slow enough so that there are not disastrous consequences over a short
period of time. Control electronics are not human, they are not intelligent and they
can not “know” when something has happened to make their input or output
invalid. If the probe is not immersed in the system, it will no longer be reading the
correct pH; either acid or base might be added in a completely uncontrolled
fashion. If solenoid valve sticks open, the controller will not be able to shut it off.
So you must be very certain that the pH probe will not become uncovered and your
needle valve settings should be chosen so that if the control solenoid valve sticks
open, you will have some reasonable period of time to notice that there is a
problem. Installing a pH Controller on your system does not mean that you no
longer have to pay attention to it. You must still monitor the system so that you
can note when a problem exists and correct it in a timely fashion.
II. GENERAL SPECIFICATIONS
pH Measurement Range 1.00 - 14.00
pH Setpoint Range 4.00 - 10.00
3 1/2 Digit LCD Display
Resolution 00.00 pH Unit
2 Independent 5 Amp 110 VAC Relay Outputs
III. Displays and Adjustments
pH Display
pH Monitor Adjustment & Instrument Status
Controller Set Point Block
Display Mode
Controller Status LED’s
110 VAC Outlets (#1 &2)
pH Probe
UPPER LEFT (pH Display)
The 3 1/2 digit LCD (Fig. A) at the top left of the controller displays a
numeric value corresponding either to the pH as measured through the probe, or
the high or low controller setpoints.
LOWER LEFT (pH monitor Adjustment & Instrument Status)
Below the display are two adjustment screws, which are used to calibrate
the electronics to properly read the pH, and two LED’s which report the status of
the instrument.
The adjustment screw marked “CALIB” (Fig. B) is used to zero the pH
monitoring electronics, and the “SLOPE” (Fig. C) is used to adjust the slope.
Detailed information on how to make these adjustments is given later.
The red POWER LED (Fig. D) is illuminated when the power is turned on to
the controller. The pH LED (Fig. E) is illuminated when the display is indicating the
