Industrial Grade EC Controller with Proportional Fertilizer Dosing for Hydroponics Applications
HI 9931 is a wall mounted meter that measures and controls conductivity in the 0 to 10 mS/cm range. A single set point allows for proportional dosage of fertilizer solutions. The proportional settings can be fine tuned through two conveniently positioned dials on the front panel. The time cycle is adjustable from 0 to 90 seconds and the proportional band from 0 to 1.6 mS/cm. Calibration and set points have a coarse and fine tuning trimmers. A pump or electrovalve can be wired directly to the controller and be powered through the terminals.
HI 9931 also provides for an alarm relay which is activated when the measurements exceed the set point by a user selectable margin from 0.5 to 2.5 mS/cm. The alarm also triggers if, due to a malfunction, the continuous dosing time exceeds the operator adjustable period of 1 to 10 minutes. The alarm can be configured in either normally closed or open position and turned off during maintenance. HI 9931 also provides an isolated output signal which is user selectable between 0-20 or 4-20 mA.
HANNA four-ring conductivity probes ending in a DIN connector can be quickly attached to the HI 9931. Readings are automatically compensated for the effects of temperature in the 0 to 50°C (32 to 122°F) range. For quick and easy wiring, HI 9931 comes with extractable terminal modules. Several LED’s show whether the set point or alarm relays have been activated.
Range 0.00 to 10.00 mS/cm
Resolution 0.01 mS/cm
Accuracy @ 20°C ±2% f.s.
Calibration through “ZERO CAL” and “SLOPE CAL” trimmers
Setpoint from 0 to 10.00 mS/cm
Compensation automatic, 0 to 50°C (32 to 122°F) with ß = 2%/°C
Recorder Output selectable at 0-20 mA or 4-20 mA (isolated)
Control conductivity from 0.0 to 1.6 mS/cm and time cycle from 0 to 90 seconds
Alarm Contact terminal can be configured as normally open or normally closed (isolated output max. 2A, max. 240V, resistive load, 1,000,000 strokes). The alarm is activated if conductivity exceeds by more than the user selectable interval (0 to 2.0 mS/cm) from the set point or due to overdosage
Dosing Terminals relay (115 to 240V, max.2A, 1,000,000 strokes) is activated whenever conductivity falls below the set point
Probe four-ring potentiometric with built-in temperature sensor and DIN connector (not included)
Power Supply ±10% 115 VAC or 230 VAC; 50/60 Hz
Environment -10 to 50°C (14 to 122°F); RH max 95% non-condensing
Case Material fiber-reinforced, self-extinguishing ABS
Dimensions 221 x 181 x 86 mm (8.7 x 7.1 x 3.4’’)
Weight 1.6 kg (3.5 lb.)
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