APERA INSTRUMENTS / DO850 / AI480

Optical dissolved oxygen, with a straightforward field-reading workflow

DO850 combines a portable meter with the DO803 luminescent optical probe and a nominal 10-ft cable. It measures dissolved oxygen concentration, percent saturation and temperature without consuming oxygen at the sensor. This AI480 kit suits spot checks where an operator records the result, rather than needing an onboard data logger.

Choose DO850 for general-water DO measurements with automatic temperature and barometric compensation, manual salinity entry and optional reading hold. It is not a pH or conductivity meter, and HOLD does not create a stored record.

An optical signal instead of oxygen consumption

A blue LED excites the sensing layer and a photodiode reads its red luminescence. Oxygen changes that optical response. This avoids the oxygen-consuming reaction of galvanic or polarographic probes and removes their continuous-flow requirement. It does not eliminate bubbles, fouling, temperature equilibration or the need to check calibration.

Two automatic corrections, one operator input

The probe supplies temperature for automatic compensation over 0 to 50°C. The meter also compensates barometric pressure over 60 to 120 kPa. Salinity is entered manually from 0 to 45 ppt, so determine the sample salinity independently before relying on mg/L or ppm in brackish or marine water.

A display that distinguishes stability from retention

DO and temperature appear together on the backlit LCD. Wait for the stability symbol to remain visible. Optional auto-lock holds a reading after more than ten seconds of stability. This helps with reading the screen in the field, but is not memory storage or a USB export function.

A replaceable cap, not a disposable probe

The DO803 has a built-in temperature sensor and eight-pin connector. Its DO8032 luminescent cap and DO8031 storage/calibration sleeve are distinct service parts. There is no electrolyte refill or conventional membrane replacement, but cleaning, humid storage, calibration and eventual cap replacement remain necessary.

Know what this configuration supplies.

Aquaculture and aquarium rounds

Compare DO at defined locations and times without continuously stirring the sample to feed an electrochemical reaction. Record water temperature and salinity assumptions alongside the result. A surface reading alone does not establish oxygen conditions throughout a tank or pond.

Water treatment and environmental spot checks

The carrying case and cable support portable sampling of compatible general water. Keep a consistent immersion depth, avoid entrained bubbles, and wait for thermal stability. The kit is not an unattended installation or proof of compliance with a particular analytical method.

Hydroponic and general-water process checks

Use the probe within its 0 to 50°C operating range. The current DO803 specification excludes strong acidic or alkaline water and organic solutions. Select a separately validated method for chemically aggressive samples rather than assuming optical sensing makes every liquid suitable.

Calibrate in humid air, then measure below the immersion line

Align and secure the eight-pin probe connector, inspect the cap and check the storage sponge. The manual asks for approximately 30 seconds after power-on before operations. No electrochemical polarization warm-up is needed, but this is not an instant-reading guarantee. Select concentration units and enter the correct salinity before sampling.

For saturated-air calibration, dampen the sleeve sponge, attach the sleeve and tighten its locking cap. Keep water droplets off the sensing surface. Allow five to ten minutes for the sleeve atmosphere and temperature to stabilize, then enter calibration and confirm only when the stability symbol remains on. For best accuracy the manual recommends this check before each day of use, despite reduced-calibration marketing language.

Zero calibration is not normally required on first use because it is performed at the factory. Perform it after replacing a probe or cap, after prolonged non-use, or when low-range accuracy at 0 to 2.0 ppm is important. The manual specifies fresh oxygen-free solution made from 2 g anhydrous sodium sulfite in 100 mL distilled or deionized water, effective for one hour; follow its handling and calibration steps.

Remove the sleeve for measurement. Immerse above the probe line, move briefly to release bubbles, then hold still until stable. The 30-second specification describes 90% response at 25°C, not the complete field cycle. The manual describes roughly one minute when temperatures are similar and about three minutes when probe and sample temperatures differ substantially.

Keep the cap humid, clean and protected

The optical cap needs humid storage, not pH-electrode KCl solution. Keep the DO8031 sleeve sponge damp with clean water, not dripping, and close the locking cap. The sensing cap should sit in humid air rather than a pool of water inside the sleeve. Replace a dirty or moldy sponge. For storage beyond 30 days, the manual permits clean-water storage or checking the sleeved sponge every 30 days.

If the sponge has dried or the probe has spent over eight hours in dry air, rehydrate before measuring. The detailed maintenance instructions specify 24 hours in clean water at room temperature, or 48 to 72 hours in cold water. During measurement, remove the sleeve and immerse above the marked immersion line. Do not confuse that sampling depth with the humid-air calibration arrangement.

Protect the cap coating from scratches and temperatures above 50°C. Clean gently with a soft clean cloth; do not use alcohol or organic solvents. The manual describes 3% hydrogen peroxide for 15 to 30 minutes when disinfection is needed, followed by a clean-water rinse. Do not routinely remove or swap sensor caps; keep the interior dry and uncontaminated.

DO8032 is the replacement luminescent cap. Its advertised 8,000-hour service figure is a design estimate, not a guaranteed interval or warranty duration. Replacement requires the correct cap calibration coefficients. The current replacement page describes a probe-connected data box and installation-program flash drive, while the meter manual refers to cap-specific calibration codes. Follow the supplied replacement instructions; neither source establishes a QR-code or RFID procedure.

Read the display. Check the measurement mode.

Use the physical controls for measurement, calibration and the documented record functions. Check units, temperature, calibration indicators and the selected parameter before assigning a result to a sample. Screen values in photographs are illustrative, not sample results. The model-specific record and output workflow is explained below.

Follow the exact parameter-specific calibration procedure, using the required standard, solution or calibration atmosphere. Temperature compensation does not make different sample temperatures, preparation methods or chemistry equivalent. Follow the model-specific meter and electrode instructions before extending the method to a new sample.

Use HOLD for reading, not for a saved dataset

DO850 is the simpler display-and-record choice. Its documented controls provide stable-reading indication and optional HOLD, but no 500-record memory or USB data workflow. Write down the result, units, temperature, sampling location and relevant calibration information in your own field record.

Choose DO8500 instead if timestamped onboard storage, timed recording or the documented USB PC-Link workflow is necessary. Those are different-model functions; the shared optical probe does not add them to DO850.