Commercial Pool and Spa Supplies
Pool Link 500 Series, TAC Probe Membrane Cap
Pool Link 500 Series, TAC Probe Membrane Cap
SKU:LINK-TACCAP
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The Pool Link 500 Series TAC Probe Membrane Cap (Pool Link / Link Automation) is the consumable front-end sensing element for the 500 Series Amperometric Total Available Chlorine (0–20 PPM) probe. Screwed directly onto the lower barrel of the electrode shaft, the membrane cap retains the specialized potassium iodide/buffer electrolyte and acts as the semi-permeable diffusion barrier separating the active pool water flow from the internal precious metal electrode assembly.
Hardware Architecture & Material Composition
Designed to facilitate multi-species chlorine diffusion while protecting internal electronics from harsh commercial water conditions:
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Catalytic Diffusion Membrane: Outfitted with an ultra-thin, microporous hydrophilic/polymeric membrane (typically treated PTFE or PVDF). Unlike direct FAC membranes, this matrix allows both free chlorine ($\text{HOCl}/\text{OCl}^-$) and combined chloramine species (monochloramine, dichloramine, and organic chloramines) to diffuse inward to react with the internal electrolyte.
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Chemical-Grade Polymer Housing: Precision-machined or molded from PVDF (polyvinylidene fluoride) or chemical-resistant polyacetal (Delrin) to withstand continuous exposure to high total chlorine residuals, ozone off-gassing, cyanuric acid, and periodic acid washes without embrittlement.
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Internal Electrolyte Reservoir: Calibrated internal volume engineered to hold 1.5 mL to 3.0 mL of TAC electrolyte gel, maintaining steady ionic contact between the noble metal cathode (platinum or gold) and the silver/silver chloride ($\text{Ag/AgCl}$) reference anode.
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Hydrostatic Pressure Venting: Features internal relief micro-grooves along the upper thread shoulder that vent displaced electrolyte and air during assembly, preventing hydrostatic over-pressurization from stretching or puncturing the delicate membrane face.
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Dual Elastomeric Seal: Incorporates an internal Viton (FKM) or EPDM O-ring to prevent sample pool water from entering the electrolyte chamber and prevent reagent leakage into the analytical bypass manifold.
Technical Specifications
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Compatible Sensor: Pool Link 500 Series Amperometric Total Available Chlorine (TAC) Probe (0–20 PPM).
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Operating pH Range: 6.50 to 8.50 pH (optimized for commercial natatorium chloramine tracking).
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Maximum Working Pressure: 50 PSI (approx. 3.45 bar) within bypass flow cells.
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Operating Water Temperature: 35°F to 120°F (2°C to 49°C).
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Service Life / Replacement Interval: Typically 3 to 6 months under continuous commercial operation (depletion occurs faster than FAC caps due to ongoing chemical interaction with chloramines and iodide consumption).
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Packaging & Storage: Shipped dry in a sealed rigid blister pack or protective carton with internal wetting/cushioning boots.
Close the inlet and outlet isolation valves on the 500 Series acrylic flow cell to relieve line pressure. Loosen the compression gland nut and slide the TAC probe out of the manifold port.
Verification: Flow cell pressure gauge drops to 0 PSI and no water weeps from the open probe port.
Unscrew the old membrane cap counter-clockwise over a waste receptacle and discard the spent electrolyte. Rinse the internal cathode tip with distilled water and gently wipe it with a soft lint-free cloth or lens paper.
Verification: The noble metal cathode surface is bright and free of yellowed iodide staining or mineral deposits.
Fill the new replacement membrane cap approximately 3/4 full with fresh, bubble-free TAC probe electrolyte gel. With the probe held vertically, slide the cap onto the shaft and thread it on slowly to allow excess gel to vent through the relief threads.
Verification: The cap seats flush against the O-ring shoulder, and the membrane face remains flat without trapped air bubbles.
Reinstall the probe in the acrylic manifold, tighten the compression nut, and reopen the bypass valves to restore 0.5 to 1.5 GPM flow. Allow the sensor to polarize electrically under power for 2 to 4 hours before calibrating against a DPD-3/4 photometer test.
Verification: The TAC PPM readout on the Pool Link 501 controller settles into a stable, non-drifting baseline.
Close the inlet and outlet isolation valves on the 500 Series acrylic flow cell to relieve line pressure. Loosen the compression gland nut and slide the TAC probe out of the manifold port.
Verification: Flow cell pressure gauge drops to 0 PSI and no water weeps from the open probe port.
Unscrew the old membrane cap counter-clockwise over a waste receptacle and discard the spent electrolyte. Rinse the internal cathode tip with distilled water and gently wipe it with a soft lint-free cloth or lens paper.
Verification: The noble metal cathode surface is bright and free of yellowed iodide staining or mineral deposits.
Fill the new replacement membrane cap approximately 3/4 full with fresh, bubble-free TAC probe electrolyte gel. With the probe held vertically, slide the cap onto the shaft and thread it on slowly to allow excess gel to vent through the relief threads.
Verification: The cap seats flush against the O-ring shoulder, and the membrane face remains flat without trapped air bubbles.
Reinstall the probe in the acrylic manifold, tighten the compression nut, and reopen the bypass valves to restore 0.5 to 1.5 GPM flow. Allow the sensor to polarize electrically under power for 2 to 4 hours before calibrating against a DPD-3/4 photometer test.
Verification: The TAC PPM readout on the Pool Link 501 controller settles into a stable, non-drifting baseline.
Close the inlet and outlet isolation valves on the 500 Series acrylic flow cell to relieve hydraulic pressure. Unthread the probe's compression collar and extract the sensor body from the manifold.
Verification: Flow cell pressure gauge drops to 0 PSI and no bypass water flows from the open port.
Unscrew the lower membrane cap and discard old electrolyte into a sink or waste container. Rinse the internal cathode tip and cap reservoir thoroughly with distilled or deionized water, then gently blot dry with a lint-free tissue.
Verification: The internal chamber is clean and the cathode surface is free of mineral buildup or discolored gel residue.
Invert the FAC Probe Gel bottle and tap it gently to dislodge air bubbles from the dispensing nozzle. Carefully fill the membrane cap approximately 3/4 full with fresh gel, avoiding micro-bubble entrapment.
Verification: The gel inside the cap is clear, continuous, and free of visible air pockets.
Holding the probe vertically, slowly screw the filled membrane cap onto the probe shaft. Allow excess gel to escape through the pressure-relief threads/vent without forcing or stretching the delicate membrane face.
Verification: The cap is firmly seated against its stop and the outer membrane remains smooth and flat.
Reinstall the probe in the acrylic flow cell, tighten the compression collar, and reopen the bypass valves. Restore steady water flow (0.5 to 1.5 GPM) and let the sensor polarize under power for 1 to 2 hours before running span calibration.
Verification: The FAC reading on the Pool Link 501 controller settles into a stable, non-drifting baseline matching a DPD photometer test.
