The HI-981413 uses an amperometric conductivity sensor for measuring the amount of fertiliser in the solution. The meter can be programmed to display results as EC (electrical conductivity) or as TDS (total dissolved solids). The EC results are displayed as mS/cm while TDS is displayed as ppm with a selectable conversion factor from 0.45 to 0.99.

The HI-981413 was developed to be an inexpensive solution for the horticulturist to maintain the ideal fertiliser concentrations at all times. Simply insert the probe and injection valve in-line with the recirculation pump and provide the chemical to be dosed.

Peristaltic Dosing Pump

The HI-981413 has a powerful built-in peristaltic chemical feed pump that utilises a stepper motor which does not have any gears or brushes to wear out. This design provides for a long life and little maintenance.

Automatic Proportional Pump Control

The peristaltic dosing pump can be controlled by simple on/off or more advanced proportional control which helps prevent overshooting of the set point. When using proportional control the flow rate that is programmed, will be impacted by the proportional band used. The closer the reading is to the set point the longer it takes for the peristaltic pump to complete one revolution. If the reading is outside the proportional band then the amount of time it takes to complete one revolution is based on the flow rate programmed.

Quick Connect Probe Input

The Quick Connect DIN connector creates a waterproof seal with the controller making it ideal for reducing electrical noise issues with the connection caused by humid environments.

For example, a controller is programmed to have a set point of 1.50 mS/cm with a 0.30 mS/cm proportional band and the flow rate at 1 L/h. Any reading above 1.80 mS/cm will cause the dosing of acid to be at 1 L/h. If the reading is at 1.65 mS/cm, which is 1/2 of the band, then the dosing pump will run at half speed or deliver 0.5 L/h of chemical. The closer the reading is to the set point the longer it takes for the pump to complete one rotation. This allows for very fine control of the EC/TDS value desired.

Adjustable Flow Rate

The flow rate from the dosing pumps is adjustable from 0.5 to 3.5L/h. Larger bodies of water require more chemical to be dosed than smaller ones in per unit of time. The adjustable flow rate, like the proportional band, allows for better control in maintaining a desired set point.

Nutrient Level/Flow Switch Input

The HI-981413 allows for a connection to an optional level controller or flow switch. This input can be used to disable the dosing pump when there is no chemical left in the reservoir tank or there is no flow due to the pump being turned off.

Programmable Alarm System

Enables or disables the low and high-level alarms for pH. When an alarm is activated, all dosing will stop. For added safety, the alarm system also offers overdosing protection in that if the set point value is not corrected within a programmed time interval then the meter will go into alarm status.

Multi-coloured LCD Display

The HI-981413 features a multi-coloured LCD that provides for a quick way to see the status of the controller. If in control mode and operating as intended the display will be green. If control is not enabled then the display will be yellow; while in an alarm state the display flashes red.

HI-30033 EC/Temperature Probe

The HI-981413 uses the HI-30033 probe that incorporates both EC (TDS) and temperature sensors and connects to the controller with a single waterproof Quick Connect DIN connector. The PVDF body of the probe has a 1/2” threaded fitting for insertion to an in-line “T” fitting or the flow cell. The back end part of the probe has 3/4” NPT threads for submersion/tank mounting. The probe body has a hex fitting for tightening snuggly with a wrench.

HI-981413-10 with in-line mounting kit package includes:

• HI-981413 controller
• HI-30033 EC/TDS/temperature probe
• Controller aspiration filter
• Controller injector
• 1/2” thread, saddle for Ø 50 mm pipe (2)
• PVC aspiration tubing (flexible) (5 m)
• PE rigid dispensing tubing (5 m)
• Conductivity calibration solution, 20 mL (3)
• Power connection cable
• Instruction manual and quality certificates for instrument and probe.