Hanna Instruments PCA 310 - Manual (Page 42)

42
ANALOG OUTPUT
The type of analog output could be set as described in “Ana-
log output” chapter. The analog output span for pH could be
set in “pH Menu” - “Analog Output pH”.
“Min. Rec” will set the recorder low limit and “Max. Rec” will
set the recorder high limit. The Max. Rec. value must be greater
than Min. Rec. value.
The output will be proportional with pH value if the read value
is between those limits.
The analog output limits could be quickly consulted in one of
the pH measuring panel.
pH DOSING
The PCA 320 and PCA 330 can use ON/OFF or propor-
tional dosing algorithm to stabilize the pH .
The analyzer has a relay for acid or alkali dosing and also the
4-20 mA output could be configured as a dosing output.
To select the type of pH
dosing edit the “pH
Menu” - “Dosing
Control pH” - “pH
Control” line. The
available options are
Proportional and
ON/OFF.
The acid or alkali dosing is set in the “pH Menu” - “Dosing
Control pH” - “Dosing Type”. When “Acid” is selected, the
analyzer will dose when the pH value is higher than the set-
point and when “Alk” is selected, the analyzer will dose when
the pH value is lower than the setpoint.
PROPORTIONAL DOSING
The proportional dosing
algorithm turns on the
dosing relay proportion-
ally with the difference
between the setpoint
and measured value.
The equation for determining the time for relay on is:
dosing time = (set value - measured value)*Period/Delta
Setpoint
delta
pH
time
Proportional dosing
Relay on
Relay off
pH Control:On/Off
Dosing Type:Acid
Period
:003 sec
Setpoint :07.00 pH
Delta :0.1
Hysteresis:1.00 pH
Max. ON
:060 min