The Model HPW-L On-line Unit and the HPW-V Portable Validation Unit are uniquely designed to benefit the user with 4 to 6 months of sensor life in water with less than 100 µS/cm conductivity while providing a stable, noise-free pH signal.
The Model HPW-L On-line Unit is designed for on-line service using ¼ inch tubing. It is built with a 316 SS, electrically isolated low flow cell which provides quiet, stable pH readings.
The easy-to-replace pH sensor uses the unique patented* porous Teflon™ reference junction to ensure a steady reference signal, temperature compensation (PT100 or PT1000) for accurate readings at any temperature, and the TOP68 connector for quick and easy sensor replacement.
A mating TOP68 cable is a standard item and is built with an integral preamplifier which boosts the high impedance signal; the cable only needs to be wired once to any manufacturer's pH analyzer or transmitter.
Once the sensor is initially calibrated, it can be installed in the flow cell to measure pH in water with conductivity of 100 µS/cm and below. Subsequent calibrations can be performed quickly and easily using the Model HPW-V Portable Validation Unit, eliminating 2-hour calibrations previously needed.
The Model HPW-V Portable Validation Unit is designed with the same features as the Model HPW-L On-line Unit and is used to validate the on-line reading.
Added features to this unit include a portable carrying stand, a rotameter for flow control, PVC hose connections with on/off valves, and a battery powered temperature compensated pH meter. The HPW-V is used to validate the reading of the pH sensor found on the HPW-L unit.
Typically, calibrating an on-line pH sensor for low conductivity water takes up to 2 hours due to reference junction offsets caused from using high ionic strength buffers rendering the pH sensor reading useless during that time.
The time for the sensor to get reconditioned back to the low ionic strength water is approx. 2 hours. With the portable validation unit, this time is virtually eliminated. Simply hook up the HPW-V to a sample port and flow the on-line sample into the HPW-V flow chamber.
Verify that the on-line sensor is reading okay and/or standardise the on-line sensors value to the value displayed on the portable unit. The on-line reading is not disturbed at all.