Benchtop Dissolved Oxygen Tester

Hangzhou Qiwei Instrument Co., Ltd. is one of the leading manufacturers and suppliers of Benchtop Dissolved Oxygen Tester in China. With a professional production team, we are able to meet the needs of the majority of our customers. Welcome to wholesale bulk Benchtop Dissolved Oxygen Tester in stock here from our factory. We also accept customized orders.

Benchtop DO Controller & Meter:

Seamless Bridge Between Lab Precision and Process Automation 

For biological research, environmental labs, and pilot-scale industrial operations that require both real-time automated relay control and lab-grade Dissolved Oxygen (DO) analytical precision, the Qiwei Benchtop DO Controller & Meter was created.

This adaptable controller enables laboratory technicians and automation engineers to continuously monitor DO concentration, log historical measurement data, and automatically drive external dosing pumps, aeration systems, or solenoid valves. It has a clear high-contrast display, dual-channel high/low relay alarm outputs, and standard RS485 Modbus-RTU communication.

Important Highlights in Brief:
Its dual-function design allows it to function as both an active automated DO process controller and a stand-alone precision tabletop meter.
-Dual Relay Alarm Control: To avoid frequent relay switching, there are independent High/Low alarm contact outputs with adjustable hysteresis.

Complete Data Management: RS485/USB ports for direct PLC/SCADA integration and CSV export, along with built-in data logging capability.
Standard BNC and multi-pin quick-connect terminals that are compatible with industrial probes and standard laboratory DO electrodes make up the Universal Sensor Interface.

This Benchtop Dissolved Oxygen Controller quantifies oxygen dissolved in liquid solutions. Air holds a steady oxygen fraction of around 20.9%, and oxygen will dissolve into water once the two make contact.

Many conditions determine how much oxygen water can retain: sufficient time and agitation for full saturation, water temperature, ambient air pressure, salinity, as well as substances that consume oxygen in the water. Given its significance to a wide range of biochemical reactions, testing the real dissolved oxygen content of water samples is indispensable.

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Operational Boundaries & Application Scenarios

1. Fermentation systems and pilot-scale bioreactors
Maintaining stringent dissolved oxygen levels is essential for cell growth and yield in both industrial fermentation and biotech research.

2. Automated Water Quality Testing and Laboratory Dosing
Perfect for toxicity studies and environmental testing labs where exact DO control is needed for long, continuous periods of time. When DO falls below specified limits, the high/low relay system immediately initiates gas purge or chemical dosing.

3. Research & Hatcheries for Recirculating Aquaculture Systems (RAS)
For pilot aquatic research tanks, it offers automatic paddlewheel/oxygenator control and continuous DO monitoring, combining the ease of desktop display with dependable automated safety threshold warnings that are available around-the-clock.

4. Pilot Plants for Wastewater Treatment and Process Improvement
allows process engineers to assess dissolved oxygen consumption rates and effectively automate blowers by acting as an easily accessible diagnostic and continuous monitoring controller in pilot aeration basins.

Note on Operational Boundaries:
intended for use in benchtop, lab, and pilot plant settings. An IP68-rated outdoor field transmitter is advised for fully submerged field installations, even tho it offers reliable relay control outputs.

This device is equipped with a dot-matrix backlight display. It supports automatic temperature compensation and offers rapid response. The bundled coated galvanic cell DO electrode ensures consistent performance during prolonged testing.

Advanced Control Logic & High/Low Relay Alarm

The Benchtop DO Controller & Meter incorporates programmable Dual Relay Outputs (High Alarm & Low Alarm) with adjustable deadband (hysteresis) settings to guaranty process stability and equipment protection.

How the Control System Operates:
1. Upper Threshold (High Alarm Control):
Relay 1 instantly activates when the measured Dissolved Oxygen level surpasses the designated High Limit (for example, > 9.0 mg/L). This contact can be used to activate cooling/ventilation systems or close oxygen enrichment valves. When the DO falls below [High Setpoint - Hysteresis Value], the relay immediately shuts off.

2. Lower Threshold (Low Alarm Control):
Relay 2 activates when the DO level drops below the predetermined Low Limit, such as less than 4.0 mg/L. To raise oxygen levels, this signal directly drives aeration pumps, spargers, or nutrition dosing equipment. When DO recovers above [Low Setpoint + Hysteresis Value], the relay is deactivated.

3. Deadband protection, or programmable hysteresis:
Users can choose a customized hysteresis margin (0.01 to 2.00 mg/L) to avoid mechanical wear and rapid relay chattering due to small oxygen changes near threshold limits.

4. Specifications for Relays:

Two SPDT (Single Pole Double Throw) dry contacts (NO/NC) make up the relay contacts.
Contact Load Capacity: 30V DC/5A or 220V AC/3A
Alarm Delay Function: During chemical dosage mixing phases, false alarms can be filtered out with a programmable response delay of 0 to 120 seconds.

Data Communication Architecture and Electrode Compatibility

1. Flexible Interfaces & Sensor Compatibility
Galvanic and polarographic dissolved oxygen sensors are both supported by this DO controller. It has a special NTC 10K/PT1000 terminal for Automatic Temperature Compensation (ATC) and a standard water-resistant BNC coaxial connector for DO signal input.

We advise combining this device with our precision benchtop dissolved oxygen electrodes, which have rapid response times and changeable membrane caps, for the best measurement accuracy and long-term stability.

2. Integration of RS485 Modbus and Data CommunicationThe RS485 Modbus-RTU Protocol enables standard master-slave communication to link up to 32 controllers to host computers, PLCs, or SCADA systems via a single bus.

Continuous Data Logging: Up to 10,000 sets of measurement data (DO, Temperature, Date & Time Stamp) are recorded in the built-in memory at customizable logging intervals ranging from one second to twenty-four hours.

Data transfer: RS485/USB conversion makes it simple to transfer data to PC analytical tools for quality auditing, Excel reporting, and continuous graph production.

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