The Hanna Instruments HI 8002 Wall Mounted Fertigation Control System with fertilization control with pH and EC
priority provides up to 10 programs to irrigate up to 32 sectors using time or volume irrigation control. Each
irrigation program has one pH and one EC setpoint. The start condition of the program, the irrigation sectors and the
time or volume for each sector are user defined. The irrigation water is pH corrected based on the pH control, with
acid or alkaline solution and can contain nutrients for crops based on up to 4 fertilizer receipts.
Correction of time or volume of irrigated water can be based on accumulated solar radiation or can be manually
requested by user. Agitator control and filter cleaning control are performed automatically. The Hanna Instruments
HI8002 reads up to 3 EC probes, one to verify the incoming water EC, and the other two are in-line redundant for
safety to measure the current irrigation water EC. The two pH electrodes are mounted in-line redundant for safety to
read the irrigation water pH. The Hanna Instruments HI8002 provides an alarm system and logging organized on user
selectable three levels.
Irrigation control differs based on the type of control: by irrigation water volume or by irrigation time; the number
of sectors that have to be irrigated, the available sources of water for irrigation
- one or more with or without
reusing the irrigation drain water. Irrigation control is started by opening the irrigation valves and starting the
main irrigation pump. The control of all these elements is performed by the controller based on concepts of irrigation
Up to 10 irrigation programs can be set by the user with different irrigation parameters: irrigation periods, type of
irrigation control, irrigated sectors and volume or irrigation time specified for each sector, conditions to start
irrigation such as time, accumulated solar radiation, low level in tanks (hydroponic crops), temperature variations,
linked to another program, priority of program, number of repetitions. For irrigation water, each program has a defined
pH set point, EC set point (if the quantity of fertilizer is dosed according with conductivity), and receipt of fertilizers.
Control of agitators is specified by programs according with the irrigation periods.
The quality of irrigation water is assured by proper control of pH and the quantity of nutrients (fertilizers) present in
Fertilizer can be dosed during irrigation using the Venturi tubes principal or with motorized valves. The control of the
quantity of dosed fertilizer can be performed using the volume counters. The system supports dosing from up to 4 fertilizer
tanks with specific receipts. The concentration of the fertilizer in irrigation water can be controlled based on the
conductivity reading, proportional with irrigation water based on the receipt or ratiometric, in which case the certain
quantity of fertilizers are added with the amount of programmed water.
The pH control is performed by the Hanna Instruments HI 8002 Wall Mounted Fertigation Control System in order to adjust the
pH of water to the irrigation program set point. The pH correction can be performed with alkaline or acid solution based on
the characteristic of the incoming water. The control of pH and EC is performed with PID, PI or proportional control. The
tuning of the PID control can be accomplished by the user manually, or automatically by the PID auto-tuning feature.
Agitators and filter cleaning
The automatic control of agitators used in fertilizers tanks and filter cleaning system complete the needs of a standard
fertigation system. In order to keep the fertilizer concentration constant before and during the irrigation program, the
fertilizers are mixed in their tanks based on the agitators program. The Hanna Instruments HI 8002 system can manage up to
two filters mounted to protect the probes and in-line dosing elements. With differential presostates, the filters are
monitored and when necessary, the irrigation programs are automatically suspended and washer filter cleaning is started.
This process removes any deposits and sediments that may appear on filters to increase the systems life.
Redundancy of EC and pH probes
For safety reasons, the systems can be equipped with 2 conductivity probes and two pH electrodes in redundancy so that the
Hanna HI800 system can generate an alarm in the case of reading differences between them. A third conductivity probe can be
mounted to verify and compensate the incoming water conductivity.