APERA INSTRUMENTS / PH850-FT / AI5560

A flat sensing face.
A controlled surface method.

PH850-FT combines the portable PH850 Value-series meter with the LabSen 373 flat pH/temperature electrode. Its POM body, flat glass membrane and surrounding PTFE ring junction are designed for clean, wet surfaces such as paper and textiles, and suitable aqueous samples.

Choose this kit when surface contact matters more than a spear-shaped probe. Reliable measurement requires a wet contact path across both the sensing glass and reference junction, consistent sample preparation and a separate results log. It is not a dry-surface scanner or a clinical diagnostic system.

Two contact surfaces, one measurement

The central flat glass membrane senses pH while the surrounding PTFE ring provides the reference junction. A wet sample must contact both, not just the central glass. The flat face suits surface work without spear insertion, but it does not remove the need to control wetting, contact position and cleanliness. The POM shaft provides practical handling around compatible samples.

Portable readings, straightforward controls

The PH850 Value-series meter shows pH and temperature together on a backlit LCD. A stability symbol helps you choose when to read, while calibration indicators show completed points. Its protective silicone sleeve, folding stand and IP57-rated instrument enclosure suit a combination of field and tabletop work. The glass sensing end still needs careful handling, and the electrical connectors must stay clean and dry.

Calibrate for the samples you measure

Automatic buffer recognition supports one to three calibration points with selectable USA or NIST series. Begin with pH 7.00 in USA mode, then add fresh acidic or alkaline buffers appropriate to the expected sample range. The meter offers selectable stability criteria and electrode slope information. Automatic recognition does not make old or contaminated buffer suitable for calibration.

Know what this configuration supplies.

Paper, textiles and leather

Compare prepared surfaces using a consistent wetting and contact procedure. The electrode manual lists wet solid and semi-solid surfaces, including paper, textiles and leather. Record the wetting liquid and preparation because added water can influence what the surface measurement represents.

Culture media and compatible aqueous samples

The current PH850-FT kit page identifies culture medium and general water solutions as applications. Use clean, compatible samples within the electrode temperature limit and avoid damaging the flat glass. A pH result does not identify organisms, establish sterility or replace a microbiological test.

Surface research, including skin

The manufacturer lists skin as a surface application. Use an appropriate, validated protocol for cleaning, wetting and contact, with suitable hygiene controls. This application listing is not a clinical accuracy guarantee, diagnosis or a claim that one surface pH value establishes skin health.

Wet both contact zones.
Keep preparation consistent.

Connect the BNC plug to the pH socket and the RCA plug to the temperature socket. Unscrew the storage-bottle cap, withdraw the electrode and rinse with distilled or deionized water. Calibrate with fresh buffers before sample work, using appropriate points around the expected pH range. Rinse between buffers and samples rather than transferring residue into the next measurement.

The LabSen 373 manual requires a clean, wet test surface and gives distilled-water wetting of skin or textiles as examples. Establish how your procedure prepares each material. Place the flat face gently against the wet area so that both the central glass membrane and surrounding PTFE ring are wetted. Do not press, scrape or rub the sensing face to force contact.

For small-volume work, choose a volume and arrangement that keep both contact zones wetted throughout the measurement. The verified sources do not establish one minimum droplet volume for every surface or liquid. A bead that touches only the central glass is not an adequate contact method. Avoid making volume claims based solely on the probe diameter.

Allow the pH and temperature reading to stabilize before recording. Keep wetting quantity, contact location, timing and sample temperature consistent when comparing specimens. Automatic temperature compensation adjusts electrode response; it does not heat the sample, standardize its chemistry or make differently prepared surfaces directly comparable.

Protect the flat glass.
Store in 3M KCl.

LabSen 373 is non-refillable. Do not confuse its internal electrolyte and blue sensing gel with the external 3M KCl storage solution. Routine care means rinsing, suitable cleaning, calibration and replenishing the soaking bottle, not opening the electrode to refill its reference.

After use, rinse the sensing end and return it to the storage bottle with enough 3M KCl to keep the membrane hydrated and junction unblocked. Screw the cap securely. Replace dirty or insufficient soaking solution and clean the bottle when needed. Do not leave the electrode stored in purified water or calibration buffer for long periods.

Keep the BNC and RCA connectors dry and free of contamination. Inspect the flat face for residue or damage if response deteriorates, and follow electrode-specific cleaning advice rather than using abrasive tools. Check calibration after cleaning. The supplied electrode is rated to 80°C even though the meter can display temperature up to 100°C.

A stable reading is the start of the record.

Use the physical controls for on-meter measurement and calibration. HOLD temporarily locks a reading on screen; write the result and its sample context in your external worksheet or record system. Screen values in photographs are illustrative, not sample results.

Use calibration solutions and settings appropriate to the parameter and fitted electrode. 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.

Read the display.
Build your own sample record.

PH850 is a direct-reading instrument. Reading memory, stored content and output are not specified for this Value-series model. Build a separate notebook or spreadsheet workflow rather than expecting stored history, timed logging or a meter download.

The stability symbol and optional automatic HOLD have different jobs. Stability indicates that the displayed reading has settled under the selected criterion. HOLD freezes a stable display for transcription; it does not create a saved sample record. Release HOLD before checking the next sample.

For surface work, record material identity, contact location, wetting liquid and quantity, preparation timing and temperature. Those details help distinguish a real sample difference from a change in handling. Keep calibration checks and electrode-care notes beside the results; the meter does not build that history for you.