Allen Associates News, Products and Specials

Aquaculture News - Latest Water Quality Monitoring Unit (WQMU)

This new, highly ergonomic water quality testing system is designed and manufactured in South Africa, market ready in August 2018. It is by far the most economical way to measure key parameters in water quality monitoring and highly suited to applications in aquaculture.

Aquaculture News - Water Quality Monitoring Unit

WQMU is a low cost, multi-sensory interface which offers the following specifications among others:

  • 2 x Temperatures (pT100)
  • Oxidation-Reduction Potential (ORP)
  • Dissolved Oxygen (DO)
  • Ammonia (NH3)
  • pH
  • EC
  • Load cell
  • Auxiliary 4-20 mA
  • Modbus RTU Interface
  • Galvanic isolation for each input
  • Automatic feeder control with or without load cell feedback
  • Totally standalone operation
  • Distance monitoring

Sensor Inputs and Operating Ranges

A1 – Temperature Sensor A2 – Temperature Sensor °C 0 100 ± 0.5 degrees C  
B – ORP Sensor mV -1000 +1000 ± 10mV  
C – Conductivity Sensor µS/cm 0 2000 ± 5 µS/cm (cater for up to 20mS/cm for boiler applications)
D – DO Sensor ppm 0.002 20 ± 0.1ppm  
E – pH Sensor   0 14 ± 0.10 pH  
F – TDS Output mS/cm 0.1 1000 ± 0.5 mS/cm (TDS = 500 x EC in mS per cm) - calculated
G – Ammonia ppm 0.01 5 ± 0.05 ppm  
H – Loadcell mV 0 20 ± 0.01 mV  
J – Auxiliary 4-20 mA Input mA 0 22 ± 0.03 mA  

The enclosure has an IP rating of 65 which means it is “dust tight” and protected from water which is projected from a nozzle. It also has wall mounting capabilities with cable entry at the bottom of the unit as well as covered cable connection. Its dimensions are 300 x 270 x 150 (W x H x D).

All measurement values, time and feeder status are displayed by a high-end 4 x 40 backlit LCD display. Five push buttons allow for input calibration for each input channel.

Bright LED light indicates communications, watchdog, alarm and input power. Furthermore, isolated Modbus serial communications at 9.6, 19.2, 38.4 and 115.2 kbps.

This unit also allows its operator to choose an input power of 9 to 18 VDC, 18 to 36 VDC or 90 to 260 VAC 5 W making it one of the most versatile water quality testing systems available.

Water Quality Testing - Feeding Control Modes

This versatile water quality testing unit boasts four different feeding control modes:

  • The installation of a loadcell in order to provide feedback for the feedweight (FW) measurement allows the WQMU to dispense a measured weight of food four times a day at fixed intervals. The FW to be dispensed at each interval can be different which allows the feedweight to be controlled according to what is necessary. (Controlled Weight at Fixed Times).
  • The WQMU also allows food to be dispensed for a Feed Period (FP) four times a day at fixed intervals. This function does not require a loadcell to be installed. The Feed Period at every Feed Time (FT) may be adjusted. (Feed Periods at Fixed Times).
  • The other option that this unit offers is for a measured weight of food to be dispensed at pre-set intervals throughout the entire day, continuously. Installation of a loadcell is required in order to provide feedback for the FW measurement. (Controlled Weight at Preset Intervals).
  • The fourth option that this WQMU provides the for food to be dispensed for a period of time at pre-set intervals throughout the day, continuously. The FT is exactly the same at each interval. (Feed Periods at Preset Intervals).

Additional Specifications

  • 8 available inputs, each made to suit the sensor types (2 RTDs share an input and common 0V)
  • Each input has individual isolation of up to 500 VDC
  • Up to 30 device addresses selected using DIP switches
  • Communications watchdog relay output
  • Serial communications port (auxiliary RS485) for future use
  • Operating temperature between 0 and 60 °C
  • The following terminal connections:
    • RTD1 - Temperature Sensor #1: two or three wire, red & white pT100 sensor
    • RTD2 – Temperature Sensor #2: two or three wire, red & white pT100 sensor
  • ORP – two wires: screen and electrode
  • COND(EC) – Conductivity: four wires, black & yellow – cell, red & green pT100
  • DO – Dissolved Oxygen: five wires, transparent ‐ve, red +ve, white & green pT100, black ‐ shield
  • pH – Hydrogen Ion Concentration: four wires, electrode, screen, 2 x pT100
  • TDS – calculated from conductivity input
  • AMM – Ammonia (Selective Ion) two wires: red electrode, screen
  • LC – Loadcell: five wires, excitation +ve and ‐ve; sensor +ve and ‐ve; screen
  • 4‐20 mA – Auxiliary Analogue Input (AAI): three wires, +ve, ‐ve, screen (or excitation +15 VDC and input)
  • Feeder relay output is normally open
  • AUXIO – Auxiliary Serial Comms RS485: two wires, Data+, Data‐
  • RS485 – Primary Serial Comms RS485 Modbus: three wires, Data+, Data‐, screen
  • WDG – Watchdog Contact Output: two wires, open on no comms, closed comms good. (Relay: 125 VAC/0.6A, 110 VDC/0.6A or 30 VDC up to 2 A resistive load)
  • ALM – Alarm Contact Output: Internal Fault, relay same as above (can be configured to be normally open or normally closed)
  • PWR – Power supply input: three wires Live, Neutral, Earth or DC +ve, DC ‐ve
  • All CIAC control, monitoring and management controllers can communicate through the communication ports provided on the WQMU

Allen Associates - High End Water Quality Testing Unit South Africa

Contact Allen Associates today to order this water quality testing unit or to find out more about water quality monitoring.

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