APERA INSTRUMENTS / LABSEN 841 · 843 · 845 / AI3145 / AI3179 / AI3237

Strong alkali and brine
with reduced alkaline error.

LabSen 841, 843 and 845 are made for strong alkaline solutions and high-salinity solutions above 5000 ppm (0.5%). Their robust HA-type glass membrane minimizes alkaline error, and a silver ion trap on the reference resists junction clogging. The 841 (BNC) and 843 (BNC/RCA with temperature) are refillable with a ceramic junction and 3M KCl; the 845 is the non-refillable 8-pin version with an open junction for PH60 and PH60Z testers fitted with the required 8-pin socket/adapter.

Listed operating envelope: pH 0–14 for 841/843; pH 1–14 for 845 (conservative range); electrode/sample temperature 0–100°C, subject to host limits. Choose the version that matches your meter’s connection and temperature requirements from the menu above. Apera warrants LabSen electrodes for six months from delivery.

BNC versions connect to the pH input of BNC pH meters. They have no temperature sensor: use a separate temperature probe supported by the host meter (Apera’s MP500 only where the meter supports it), or manual temperature entry where available.

BNC/RCA versions carry a built-in 30 kΩ NTC temperature sensor on an RCA plug for automatic temperature compensation on Apera meters with BNC and RCA inputs, such as the PH700, PH850, PH8500, PH820, PH910 and PH9500. Apera notes they may not work with other brands’ meters because the thermistor might not be compatible.

The 8-pin version is a pH/temperature electrode for Apera meters with an 8-pin socket, including the PH60, PH60-Z, PH400, PH400S and the PC400, PC400S, SX736 and SX751. PH60 and PH60Z require the appropriate installed 8-pin socket/adapter; this cabled electrode does not replace the native tester probe directly. Confirm the adapter separately; its inclusion is not implied.

Temperature figures are electrode/sample ratings, not a complete-system rating. Use a meter and temperature-compensation method rated for the actual sample temperature; keep the meter body, cable connection and adapter within their own confirmed limits. Connector fit alone does not establish temperature or ATC compatibility.

Check the specifications.

Operating envelope: pH 0–14 for 841/843; pH 1–14 for 845 (conservative range); electrode/sample temperature 0–100°C, subject to host limits. Common construction: body lead-free glass.

Junction: 841 ceramic; 843 ceramic; 845 open.

Reference electrolyte: 841 3M KCl; 843 3M KCl; 845 polymer.

The full specification table is in the Product Specifications tab. The 845 is listed here at pH 1–14, the narrower range shared by its standalone page and kit manual. The 0–100°C electrode limit follows the current standalone pages; wider 130°C values in some manuals are not adopted here.

Keep the tip in its cap with 3M KCl storage solution whenever it is not measuring.

Never store a pH electrode in pure, deionized or distilled water.

The 841 and 843 are refillable: keep the fill hole open while measuring and top up the reference electrolyte when the level drops.

The 845 is sealed and needs no refilling.

Apera’s manual advises avoiding strong acids and dehydrating media such as absolute ethanol or concentrated sulfuric acid; if exposure is unavoidable, keep immersion short and clean the electrode carefully afterward.

Rinse with distilled or deionized water between samples. For stubborn deposits, use Apera electrode cleaning solution, then recondition and recalibrate.