HEAT INSULATION The Model RF/IT Insulator Tester is a highly sensitive device, designed to test the effectiveness of above-ground pipeline insulators. The unit can test pipeline insulators in parallel or in series even if one or more of the insulators are not operating properly. The tests conducted are fast and accurate, since high resistance shorted insulators are as easy to determine as low resistance shorted insulators. The Tester is equipped with an audible signal circuit, and the tone frequency varies from slow to fast according to resistance across probes. The lower the electrical resistance of the insulator, the faster the frequency of the audible signal. Batteries exchange in seconds through a panel in the access door. The Tester consists of a portable battery powered electronic instrument with detachable probes for making positive electrical contact across the insulator. The instrument is packaged in a plastic case complete with batteries and comes ready to operate. Two extra steel needle points are supplied with the Tester. The unit is factory calibrated and needs no field adjustments. Calibrations are made with the probe wire conductors supplied with the unit. The model number RF/IT includes the following: Instrument, complete and ready to operate. Six AA batteries. Needle point probes with two extra needles.