อุปกรณ์วัด Control System (Industrial Grade pH & TDS Controller with Proportional Control of Fertilization)

HI 9935

Industrial Grade pH & TDS Controller with Proportional Control of Fertilization

HI 9935 is a pH and TDS controller for fertilizer solution dosage in hydroponics.
HI 9935 measures pH from 0 to 14 and TDS from 0 to 1999 mg/L (ppm). Two separate set points can be adjusted from 4 to 7 pH and 900 to 1800 ppm (mg/L). The relays are activated when the pH exceeds the set point or TDS falls below the desired value. Two pumps or electrovalves can be wired directly to the controller and be powered through the terminals. Independent proportional settings for pH and TDS can be adjusted from 0 to 90 seconds, 0 to 2.0 for pH and 0 to 400 mg/L (ppm) for TDS. A matching pin/ground probe can be connected to the appropriate terminals to extend electrode life and eliminate interference.

HI 9935 provides for an alarm relay which is activated in several circumstances. These include when the pH is below the set points in the operator adjustable threshold of 0.5 to 2.5 pH, or similarly, TDS exceeding the set point by a value in the 50 to 450 mg/L (ppm) range. The alarm also goes off if the pH and/or TDS are not corrected within the operator determined time frame of 1 to 10 minutes. Moreover, the alarm configuration is switchable from a normally-closed to a normally-open state or turned off during maintenance. The fertilization status can be ascertained from a distance through dosage and alarm LED’s.

HI 9935 accepts pH electrodes with a BNC connector and TDS probes with a DIN connector.

Specifications

Range pH 0.00 to 14.00 pH
TDS 0 to 1999 ppm (mg/L)
Resolution pH 0.01 pH
TDS 1 ppm (mg/L)
Accuracy @ 20°C pH ±0.02 pH
TDS ±2% f.s.
Input Impedance  1012 Ohm
Calibration  through “OFFSET” and “SLOPE” trimmers for pH, and “ZERO CAL” and “SLOPE CAL” for TDS
Setpoint  from 4.0 to 7.0 pH and 900 to 1800 ppm (mg/L)
TDS Conversion
Factor  0.65 mg/L (ppm) = 1 µS/cm
Temperature
Compensation (TDS)  automatic, 0 to 50°C (32 to 122°F) with ß = 2%/°C
Proportional
Control  two independent controls: pH from 0.0 to 2.0 and TDS from 0.0 to 400 ppm (mg/L) with two separate time cycles from 0 to 90 seconds
Alarm Contact  terminals 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 pH falls below the set point by the user selectable interval (0 to 2 pH),or TDS exceeds the set point by more than the user selectable interval (0 to 400 ppm) or due to overdosage
Dosing Terminals  two sets of independent terminals (115 to 240V, max. 2A, 1,000,000 strokes) are activated whenever pH exceeds the pH set point and for the TDS falls below the TDS set point
Probe  any combination pH electrode with a universal BNC connector and HANNA TDS four-ring potentiometric probe 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.)

Accessories

Solutions
HI 7004/1L  4.01 pH Buffer Solution
1 x 1 L bottle
HI 7007/1L  7.01 pH Buffer Solution
1 x 1 L bottle
HI 70442L  1500 mg/L (ppm) TDS Solution, 500 mL Bottle
Probes
HI 3001D  Flow-thru Conductivity Probe with DIN Connection and 3 m cable