TROLL 9500 Operator's Manual - Geotech Environmental Equipment

Section 13: Dissolved Oxygen—PolarographicPreparation for 100% D.O. Calibration in WaterThe bubbler cal kit for the Polarographic D.O. sensor comes with(1) Battery-powered air pump and 2 alkaline D-cells, (2) Bubblercup with aquarium stone, tubing, check valve and pinch valve, (3)Grey PVC adapter to support the TROLL 9500 in the top of thebubbler cup.1. Install the batteries in the portable air pump as shown in thediagram on the inside of the lid.2. Fill the bubbler container almost to the top with clean water. Theoptimum amount depends on the volume of the sensors installedin the MP TROLL 9500.TIP: Tap water is fine, unless it is high in salinity. It is easierto achieve 100% oxygen saturation in low-salinity water.Distilled water is readily available and works well.3. About 10 minutes before calibration, turn on the bubbler. Regulatebubbling with the pinch valve. For best results, run at the fullflow rate to achieve saturation; after 10 minutes you can use thecontrol valve to match the water turbulence conditions expectedin the field.4. Before beginning the calibration procedure, note the membranethickness stamped on the membrane module.5. With the D.O. sensor installed and plugs or sensors in theother sensor ports, rinse the front end of the MP TROLL 9500thoroughly in clean water to remove contaminants and traces offluids used for earlier calibrations.6. When ready to calibrate, place the adaptersecurely in the top of the bubbler housingand insert the front (sensor) end of the MPTROLL 9500 into the adapter.• Insure the D.O. sensor is not in theaeration path. Rotate as necessary toprevent air bubbles from collecting onthe membrane surface.• Insure the temperature sensor is submerged at least 0.5” (12mm) in the aerated water.Allow a few minutes for the temperature to stabilize,especially if you plan to enter a temperature dependentvalue from a look-up table.6Preparation for 100% D.O. Calibration in AirTIP: Before beginning the calibration procedure, checkthe side of the membrane module for the membranethickness.1. With the D.O. sensor installed and plugs or sensors in theother sensor ports, rinse the front end of the MP TROLL 9500thoroughly in clean water to remove contaminants and traces offluids used for earlier calibrations.2. Dry the D.O. sensor membrane by shaking the probe and/orgently wiping with a soft swab or the corner of a tissue.3. Rinse the empty Cal Cup and attach it to the MP TROLL 9500.Thread the Cal Cup onto the body until it is seated against theo-ring, then back off slightly to avoid overtightening.4. Invert the TROLL with Cal Cup attached and remove the blackend cap from the Cal Cup.5. Gently fill the Cal Cup with clean water until the temperaturesensor is completely covered and the membrane at the tip of theD.O. sensor is in air. If any water splashes onto the membrane,gently blot the center of the membranewith a clean cotton swab or the corner ofa soft lint-free tissue.6. Loosely attach the end cap to the CalCup. For proper venting, a small hole inthe threads of the cap should be at leastpartly visible to achieve ambient pressureconditions.You may wish to use a clamp or othersupport to maintain the TROLL 9500 inthis inverted position.Allow a few minutes for the temperature to stabilize,especially if you plan to enter a temperature dependentvalue from a look-up table.6TROLL 9500 Operator’s Manual 820095110 rev. 007 01/09