Principle of Operation
The 5500 Series dissolved oxygen sensor contains a small chamber with two metal electrodes and an electrolyte, sealed by a selective membrane. Water and dissolved ionic substances cannot pass through this membrane, but oxygen and a certain amount of other gases and hydrophilic substances can. Immersing the dissolved oxygen sensor in water enables the measurement of dissolved oxygen. Due to galvanic action or an applied voltage, a potential difference is created between the electrodes, causing metal ions to enter the solution at the anode, while oxygen passing through the membrane is reduced at the cathode. The resulting current is directly proportional to the transfer rate of dissolved oxygen passing through the membrane into the electrolyte, and this current is proportional to the partial pressure of oxygen in the water sample at a given temperature.
Typical Applications
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The 5500 Series dissolved oxygen sensor is primarily used for dissolved oxygen measurement in municipal wastewater and industrial wastewater treatment plants. Typical applications include
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aeration tanks, aerobic/anaerobic digesters, and final effluent. It is also suitable for dissolved oxygen measurement in various water bodies such as natural water, wastewater, and saline water.
Advantages
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The 5500 Series dissolved oxygen sensor can be used with GLI's D63, D53, D33, and PRO-D3 dissolved oxygen analyzers or transmitters.
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The 5500 Series dissolved oxygen sensor features an integrated replaceable membrane head assembly, making replacement simple and quick. - Since each assembly includes a pre-installed membrane, electrolyte, and electrodes, replacing the assembly replenishes all consumables required by the dissolved oxygen sensor.
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The 5500 Series dissolved oxygen sensor uses polarographic Clark cell technology and consists of a three-electrode system: a gold cathode, a silver anode, and a silver reference electrode. The silver reference electrode is polarized with a constant voltage to provide voltage stabilization, making dissolved oxygen measurement more stable and accurate.
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Built-in self-cleaning system. Self-cleaning options include a compressed air cleaning system, which can be programmed to automatically clean the sensor membrane.
Specifications
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Wetted materials Noryl® and 316 stainless steel body, PVC mounting adapter, Viton® O-rings, Teflon® membrane, Noryl® and Ryton® components, and nylon cable clamps and overflow riser
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Electrode material Gold cathode, silver anode, and silver reference electrode
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Temp. range 32~122℉ (0~50℃)
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Temperature compensation NTC 30 KO resistor
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Minimum flow rate approx. 0.016 ft (0.5 cm) per second
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Maximum pressure 145 psi (10 bar)
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Measuring range 0.0~40.00 ppm
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Sensitivity ±0.05% of range
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Repeatability ±0.5% of range
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Response time (20℃) approx. 130 seconds to reach 90% of step change
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Membrane thickness 2 in (50 microns)
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Sensor cable (included) 15 ft (4.6 m) cable, terminated with MS-type quick-disconnect plug (metal or plastic)
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Measuring principle Three-electrode polarographic Clark cell technology
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Electrical certifications CSA and FM certified; GLI's D53 model can be used in Class I, Div. 2 (Groups A~D) hazardous areas
Source: Public information from the HACH Water Quality website
Case Studies
Municipal Wastewater Treatment · Controllers and Sensors — Application Case
Site Conditions
This is a Municipal Wastewater Treatment customer whose plant is at the inlet, biological and outlet stages of a municipal plant. The main task was online water monitoring with a controller and sensor combination.
The Problem
The difficulty lies in high solids and corrosive fractions, with large diurnal flow swings; at the same time effluent parameters drift and probes foul with sludge and biofilm. Specification therefore means matching each controller channel to its sensor type.
What We Did
We took a Hach channel approach — supplying against the Hach original part numbers. Delivery was built around matching each controller channel to its sensor type, with point-by-point checks on: stable compliance with Grade 1A discharge limits and online data reporting.
Operating Outcome
In service the system performs as intended — factory-matched combinations that make faults easier to locate, with routine maintenance falling noticeably.
Food & Beverage · Controllers and Sensors — Application Case
Application Context
dosing, pasteurising, filling and CIP stages is a typical Food & Beverage duty. The project started from Controllers and Sensors, focusing on online water monitoring with a controller and sensor combination.
Process Constraints
frequent cleaning demands instruments that withstand hot CIP/SIP caustic cycles, and syrups, dairy and beverages that scale easily, under strict hygienic requirements only amplify it. The Controllers and Sensors specification must therefore cover matching each controller channel to its sensor type.
Delivery Approach
Delivery was handled as the Hach channel — supplying against the Hach original part numbers. Execution centred on matching each controller channel to its sensor type, together with food-safety and hygienic design per 3-A / EHEDG.
Field Results
Operation shows the benefit clearly — factory-matched combinations that make faults easier to locate, with confidence in this measuring point improving markedly.
Chemical & Pharmaceutical · Controllers and Sensors — Application Case
Customer Profile
The typical setting in Chemical & Pharmaceutical is reactors, metering vessels and finished-product tanks. The measuring point is Controllers and Sensors; the focus is online water monitoring with a controller and sensor combination.
Key Difficulties
Conditions are highly corrosive media with solvents and crystallisation, partly in explosive atmospheres and, on top of that, corrosion plus Ex protection shortens instrument life and makes downtime costly, which a standard configuration cannot handle for long. The design therefore starts with matching each controller channel to its sensor type.
Implementation
The scope ran through the Hach channel: supplying against the Hach original part numbers. Technically it hinges on matching each controller channel to its sensor type, and on these requirements: Ex certification and GMP traceability of records.
Customer Benefit
In practice this means factory-matched combinations that make faults easier to locate, which cut the workload on the site maintenance team.
Power & Energy · Controllers and Sensors — Application Case
Project Background
The project covers boiler feedwater, turbine condensate and FGD/DeNOx systems. The work centres on Controllers and Sensors and the core task is online water monitoring with a controller and sensor combination.
Operating Challenges
The medium and duty are characterised by high temperature and pressure with both steam and saline water, and drift under high temperature and pressure, with very costly unplanned outages. So Controllers and Sensors cannot be specified generically — it calls for matching each controller channel to its sensor type.
Solution
The Ainstru engineering team worked through the Hach channel: supplying against the Hach original part numbers. The configuration involves matching each controller channel to its sensor type, with these requirements in view: compliance with power-industry codes and unit availability targets.
Results
Since start-up the system has run steadily; the practical result is factory-matched combinations that make faults easier to locate.
Related Products
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HACHSludge blanket monitor (ultrasonic)
HACH9582 dissolved oxygen meter
HACH