APERA INSTRUMENTS / PH8500-HT / AI5566

Hot, complex and caustic baths.
Start with a junction that stays open.

The PH8500-HT pairs Apera’s portable PH8500 meter with the Swiss LabSen 863 pH/temperature electrode. Apera designs the 863 for high-accuracy pH measurement of complex and caustic solutions up to 130°C, such as electroplating baths, with a chemically resistant PHY glass membrane, a PTFE ring junction that resists clogging by complex chemicals, and a non-flowing blue gel reference.

Choose AI5566 when the sample chemistry, rather than portability alone, decides the electrode. Apera lists the LabSen 863 at 1–13 pH and 0–130°C. The meter measures and compensates temperature from 0 to 100°C, so plan compensated readings within that window. The gel reference needs no refilling, but the tip still has to be stored wet in 3M KCl.

PHY glass for heat and chemical attack

Apera describes the PHY membrane as highly resistant to chemical corrosion, maximizing reliability and service life in complex and high-temperature solutions. It is a cylindrical bulb rated to 130°C; it is still glass, so avoid impact and thermal shock.

PTFE ring junction

Complex baths such as plating solutions block small ceramic junctions and cause drift. The 863’s PTFE ring junction is specified to prevent junction clogs from complex chemicals. Immerse the full ring during measurement.

Gel reference, built-in temperature sensor

A blue KCl gel reference does not flow and does not form air bubbles, so there is nothing to refill. A 30 kΩ NTC sensor is wired to a separate RCA plug; connect both BNC and RCA leads for automatic temperature compensation.

Where this configuration fits.

Use the PH8500-HT for electroplating and metal-finishing baths, hot process liquids and complex or caustic mixtures that foul conventional ceramic junctions, measured within the electrode’s 1–13 pH range and the meter’s 0–100°C compensation range.

Apera’s manual advises against using the 863 in strong acid and strong alkali solutions, as well as dehydrating media such as absolute ethanol and concentrated sulfuric acid. For strong acids and fluoride-containing samples, compare the PH8500-HF with LabSen 833; for strong alkali and high-salinity samples, the PH8500-SA with LabSen 843 is the matching configuration.

Calibrate near the working temperature.
Then let the reading settle.

Connect the electrode’s BNC plug to the pH input and the black RCA plug to the temperature input. Twist off the storage bottle cap, pull out the electrode and rinse it with distilled or deionized water. There is no refill plug on the 863.

Apera specifies at least a two-point calibration before a new electrode is used. The PH8500 always starts at 7.00 pH (6.86 pH in the NIST series), then takes 4.00 or 1.68 pH for samples below 7 and 10.01 or 12.45 pH for samples above 7; a three-point calibration covers both sides. Where practical, calibrate with buffers near your working temperature.

Immerse the bulb and the full PTFE ring, allow the electrode to reach sample temperature, stir gently and wait for the stability icon. Automatic temperature compensation corrects the electrode response; it does not remove real pH changes that happen with temperature. Use heat-resistant PPE with hot baths.

No refilling.
Store the glass wet.

The 863 uses a sealed gel reference, so there is no electrolyte to top up. When the electrode is not in use, keep it in the storage bottle with 3M KCl soaking solution to keep the membrane and PTFE junction in condition. Replace the solution if it becomes contaminated, and never store the electrode in distilled or deionized water.

Rinse with pure water before and after each measurement. For tough contamination, Apera specifies cleaning solution AI1166 for 30 minutes, a soft brush, then at least one hour in 3M KCl before rinsing and recalibrating. Let a hot electrode cool gradually; do not move it straight from a hot bath into cold buffer.

Keep the BNC and RCA connectors clean and dry. Apera puts typical pH-electrode service life at 12–24 months and recommends replacement every 12–18 months; hot caustic duty sits at the demanding end of that range. The replacement electrode is LabSen 863, AI3176.

Read the meter.
Know what is held.

Use the physical controls for standalone measurement and calibration. The stable-reading indicator and HOLD help you read a result; a held display is not a stored record.

The PH8500 measures −2.00 to 16.00 pH at 0.01 or 0.1 pH resolution with ±0.01 pH ±1 digit accuracy, mV from −1999 to 1999, and temperature from −5 to 100°C. A calibration reminder can be set in days or hours. The meter runs on three AA batteries or 5 V USB power and carries an IP57 rating.

Build a local record.
Keep the transfer workflow clear.

The PH8500 can retain up to 500 data sets, including number, date, time, measured value, unit and temperature. M+ saves a reading manually after stability, and timed logging records automatically at the interval you set. Deleting stored data cannot be undone.

For computer work, connect the supplied USB cable and use PC-Link or the browser-based Web PC-Link on a desktop Chrome or Edge browser under Windows or Mac to download records and export them. While connected to PC-Link, new readings go to the software rather than to meter memory, so export before closing the session.

Check the electrode limits.
Then the meter’s.

Apera lists the LabSen 863 at 1–13 pH and 0–130°C, with a PHY cylindrical membrane, PTFE ring junction, silver-ion-trap gel reference, 30 kΩ NTC temperature sensor, lead-free glass body (Ø12 × 120 mm), membrane resistance below 500 MΩ, a 1 m cable and BNC plus RCA connectors.

The meter’s automatic temperature compensation covers 0–100°C. Keep samples, buffers and the electrode within those limits, and confirm suitability with Apera’s documentation before measuring unusual chemistries.