OxyGuard Model 420 Dissolved Oxygen Probe with Built-in Transmitter The Model 420 is a membrane covered galvanic oxygen probe with built-in two-wire 4-20 mA transmitter. The probe is connected to a DC supply and draws a current of between 4 and 20 mA corresponding to the oxygen concentration. There are only two wires to connect, and there is no limit to cable length. The output signal is galvanically isolated from the built-in electronics and the process fluid. Interference between the Model 420 and other equipment can never occur! The OxyGuard Model 420 can therefore be connected directly to a wide range of equipment that can accept a 4-20 mA input, such as alarms, indicators, controllers, recorders, PLC's, PC systems with A/D input etc. The Model 420 can also be used to measure gaseous oxygen concentration. Technical Advantages * Extremely high stability - zero adjustment is never needed, calibration seldom. * No regular maintenance needs. The robust membrane, 50 µ thick, is easily cleaned, but if damaged can be replaced by anyone - at negligible cost. * Correct measurements with flow as low as 1 cm/s. * Based on a chemical principle superior to that of traditional DO probes. * Galvanic type - True zero. * Built-in temperature compensation. * No practical limit to cable length - extension can be made with any type of cable. * Wide range of armatures and fixtures - e.g. the AirAlarm for worker safety in areas where fluctuating oxygen levels could occur in the air, a Flow Cell for measuring gases etc. Ask for details. * Wide range of accessories - e.g. the EasyCal calibrator, OxyClean compressed air cleaner etc.

Technical Information Specifications Dimensions: Weight: Measurement Principle: Operating Conditions: Flow Requirements, water: Loop Power Supply: Dia. = 58 mm, h = 92 mm + 22mm cable gland. Standard cable length = 7m. Approx. 600 g incl. cable. Galvanic cell, self polarizing, self temperature compensating. 0 to 50°C, submersible to 50 meter. Minimum flow dependent on DO and temperature, typically 1 cm/sec. Depends on loop impedance. 24 volt DC recommended. Minimum supply with 50 ohm loop impedance 12 volt DC. Abs. max. supply voltage 35 volt DC. This permits total loop resistance 1200 ohm. ....