APERA INSTRUMENTS / DO8500 / AI485

Optical DO with salinity compensation and a record of the round

DO8500 adds timestamped storage and automatic salinity compensation to a portable optical DO workflow. The AI485 kit includes the DO803 optical probe with nominal 10-ft cable, a separate salinity electrode and a clip for measuring together. It is designed for general-water sampling where salinity changes and saved results both matter.

Choose DO8500 when manual or timed storage and a salinity input measured by the included electrode are useful. The salinity electrode supports DO compensation; this is not a general pH/EC multiparameter kit.

Optical sensing without oxygen consumption

A blue LED excites the luminescent layer; a photodiode detects its red optical response. The probe does not consume oxygen, so measurement does not require continuous sample movement. Still remove bubbles, inspect the cap and allow temperatures to equalize. Optical design is not a guarantee of immediate readings in every sample.

Salinity compensation has its own electrode

The included 2301-3M conductivity electrode supplies the salinity input used for automatic DO compensation. Connect it and choose automatic mode; use the combined clip to measure with the DO probe. Manual entry from 0 to 45 ppt remains available. Do not assume the optical probe alone measures salinity.

Read status before saving

The LCD distinguishes a stable reading, HOLD, M+ saving, RM recall, timed storage and USB communication. The manual shows salinity when its probe is connected and salinity exceeds 1 ppt. HOLD is a reading lock, separate from the commands that actually store records.

Field handling with a serviceable sensor

The IP57 instrument has a backlight and folding stand, and travels in a carrying case. The DO803 integrates temperature sensing and uses a replaceable optical cap. Protect connectors and seals, and keep the cable clear of sharp edges. The ingress rating does not make every accessory or connected computer waterproof.

Know what this configuration supplies.

Brackish-water and marine checks

Automatic salinity compensation reduces repeated manual entries when moving among waters of different salinity. It depends on the connected, functioning salinity electrode and the selected mode. Record sampling depth and temperature so comparisons reflect a consistent procedure.

Treatment-process sampling rounds

Store readings with date and time at successive locations, then preserve location identifiers in your own records. Timed recording can follow a defined sampling interval; it does not by itself establish sample representativeness or replace an installed process sensor.

General-water laboratory comparisons

The stand and probe clip support repeated bench checks. Use compatible aqueous samples within 0 to 50°C. DO803 is not specified for strong acid, strong alkali or organic solutions; determine suitability before applying it to aggressive process liquids.

Prepare the DO and salinity paths separately

Connect the DO803 eight-pin plug, secure the connector and inspect the sensing cap. Allow about 30 seconds after power-on before operations. Check the clock if storing data. Select automatic or manual salinity compensation deliberately; automatic mode requires the salinity electrode to be connected, not merely a setting change.

The salinity electrode is factory calibrated. The manual calls for recalibration when it is replaced or has not been used for a long time. In automatic mode use the specified 12.88 mS/cm conductivity standard in the salinity calibration menu, allow the reading to stabilize, then confirm. This standard is for the salinity electrode, not the optical DO saturated-air point.

For DO calibration, use the storage sleeve with a damp, non-dripping sponge. Keep water droplets off the sensor cap and wait five to ten minutes for humidity and temperature to stabilize. Confirm the saturated-air calibration only after the stability icon remains visible. The manual recommends daily saturated-air calibration for optimal accuracy, despite promotional suggestions of infrequent calibration.

Zero calibration is factory performed and normally unnecessary on initial use. It is specified after probe or cap replacement, prolonged non-use, or for demanding work at 0 to 2.0 ppm. Follow the manual’s fresh sodium-sulfite solution procedure. For measurements remove the sleeve, immerse above the marked line, briefly dislodge bubbles and wait for stability. Full equilibration can take about one to three minutes; the 30-second specification is only 90% response at 25°C.

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.

500 records, with a model-specific legacy USB route

DO8500 stores up to 500 groups with date and time. Use manual saving for individual samples or set the automatic timing interval for a series. Manual saving is unavailable while timed-storage mode is active. Check the clock before collecting a batch, review records with RM and export before clearing the complete memory.

The exact manual documents DO8500 PC-Link, a Windows driver and COM-port connection, Download and Export to a Microsoft Excel file. In connected real-time operation, readings are sent to the computer rather than retained in meter memory. Keep the computer session and exported file under your own record-retention procedure.

This is the legacy DO8500 workflow, not evidence of compatibility with 9500 software, 480-series software or a browser-based PC-Link service. Verify the delivered meter revision and host-system requirements before purchase if USB use is essential. No software installation, startup or compatibility test is implied, and the kit is not represented as compliance-certified data management.