Hanna Instruments HI 8050 User Manual

Page 10

Statistical values of pH are displayed on panel C20

C20

C20 (TOTAL AVERAGES).

For each irrigation program the pH average is available on panel C21

C21

(PROGRAM AVERAGES) and for each individual sector the pH average
is available on panel C22

C22

C22 (SECTOR AVERAGES). All pH averages can

be deleted manually or at specified time of day using panel S65

S65

S65 (ERASE

STATISTICS)

PROPORTIONAL CONTROL

PROPORTIONAL CONTROL
EC and pH control is performed using a proportional controller.
The role of this controller is to maintain a pH and EC value of the irriga-
tion water (see diagram). The control of pH and EC is made separately.

A simplified schematic of the process (pH and EC) is presented above.
The components are as follows:
−The mixing tank where input water and additives are combined.

−The additive solution tank containing an acid, base or fertilizer

−The valve for introducing the additive solution into the mixing tank con-

trolled by the proportional controller.

−P(proportional) Controller

−The input water source.

−The irrigation pump used to pump water from the mixing tank to the

irrigation sectors.

The Fertigation controller automatically provides a command output sig-
nal to a control element such as a pump or valve based on a sensor input
signal. The function of the proportional controller is to control the dosage
of acid/base or fertilizer in such a way that pH and EC of the process will
have the values close to specified set point. The output signal commands
the opening and closing of a valve through which the additive solution is

Reagent

This manual is related to the following products:

HI 8060