D. E. Stearns
1. HOLIDAY DETECTOR FUNCTION. The D. E. Stearns Model 14/20 Voltage Regulated Holiday detector is a portable, all-purpose electrical inspection instrument which maintains a given inspection voltage in spite of the electrical load on the circuit or the charge on the battery. It is recommended for use on any pipe diameter as well as on flat surfaces when such surfaces are coated with a highly electrical resistance material, and when the surface beneath the coating is electrically conductive. The detector works equally well on damp or dry surfaces, and is especially desirable where humid conditions prevail.
2. INSTRUCTIONS FOR UNPACKING & INSPECTION. A. Open the carrying case and make note of where the various accessories are located. To ensure proper storage, repack accessories in the same manner when not in use. B. INSPECTION should be made upon receipt. If damage has occurred during shipment, file a claim with the carrier immediately. C. If it is necessary to contact your supplier or the manufacturer concerning damaged or missing items, be sure to include the serial number, purchase order number, and invoice number of the instrument in question.
3. CHECK-OUT INSTRUCTIONS. A. Remove all accessories from the carrying case with the exception of the battery charger. (The instrument is shipped with two batteries, one of which us already in the unit). B. Make sure that the detector is turned OFF. C. Using the VOLTAGE SELECTION TABLE on the back panel, select the specific voltage required Unscrew the protective cap on the SELECTOR and use a screwdriver to turn the switch to the HI or LO position. Replace black plastic cap cover. Use same procedure to adjust voltage settings. CAUTION: ALWAYS CHANGE HI-LO SWITCH WITH DETECTOR TURNED OFF. D. Connect high voltage cable and ground cable to detector (insert and twist clockwise). E. Attach probe handle to voltage cable. F. Attach electrode to the voltage probe assembly and apply to the structure to be inspected. The electrode should always make intimate contact with the surface under inspection. G. The Model 14/20 Holiday Detector is now ready to operate.
4. OPERATING METHODS. A good ground return system for both the pipe and the detector will always provide the best and most reliable inspection. The pipe to be inspected must be grounded from the bare pipe to earth at some point along the pipe. If individual joints of the pipe are to be inspected that are not electrically connected, each joint must be grounded. The speed of the electrode's travel along the pipe should never be excessive, since faulty inspection may result. Occasional checks of the detector operation should be made, particularly if no holidays are being found. This can be accomplished by testing for the spark and signal at the edge of the coating where bare pipe exists, or by touching the probe end to the bare pipe and noting the length of the spark and the signal effectiveness. If the signal does not occur when the spark discharges from the electrode into a known holiday, the ground return (i.e. the path between the metallic pipe and earth and the earth to the ground trail of the detector) is of high resistance. In this case, a better ground is required and a direct connection between the metal pipe and the ground wire may be necessary. This type of grounding is extremely uncommon unless the soil is very dry of the detectors output is low. Correct voltage output for a given thickness of coating has long been a matter of controversy.
Recent formulas have been suggested which may be used as a guide for correct peak voltages on various coating thickness. The calculation is as follows:
V = K √T WHERE
V = Peak voltage in volts.
√T = Squareroot of the Thickness of bonded coating in mils (not including outer wrappers).
K = Constant of 1,250 for coatings over 30 mils and 525 for fusion bonded epoxy coatings.
These formulas when applied to a coating of 3/32" thickness and with a constant of 1,250 would indicate an applied voltage of 12,500 volts peak or a coating of 16 mil thickness and with a constant of 525 would indicate an applied voltage of 2,100 volts peak. A common practice used in setting inspection voltages in the field I s to adjust the output voltage by visual observation. It is the general consensus that spark discharge at least twice the thickness of the coating will give adequate inspection voltage and compensate for any irregularity in coating thickness and grounding conditions. If this practice is desired for determining inspection voltage, it should be done while the electrode is in the normal operating position and under actual grounding conditions. The formulas and suggestions for setting voltage are supplied as a guide, and are not recommended by the manufacturer of this detector. Unless output voltage is specified, the voltage is factory set at 14,000 volts at time of shipment. Consult the coating manufacturer for recommended voltage applications.
5. INSTRUMENT SERVICING INSTRUCTIONS. A. Cleaning: Keep the instrument clean and dry. Clean the instrument case with a soft cloth dampened with kerosene, then wipe dry. Do not use solvents such as lacquer thinner, methyl ethyl keytone, etc. KEEP ALL ELECTRICAL CONTACTS CLEAN. B. Voltage Output Checks A. In case of LOW output voltage: a. Check position of voltage selector switches. b. Check battery (is it fully charged?). c. Check for "parted conductor in voltage probe and/or ground trail. B. In case of NO output voltage: a. Check battery. b. Check for "parted" conductor in voltage probe and/or ground trail. c. Check battery contacts. MAKE SURE THEY ARE CLEAN.
6. BATTERY CHARGING INSTRUCTIONS. A. Use ONLY the battery charger provided. B. Charge battery nightly after use. C. To charge battery in the instrument. a. Connect plug of the battery charger to jack on battery through access door. b. Plug AC power cord into proper outlet. C. Charger indicator light is on during charging. It will begin to flash on and off when battery is fully charged. D. To charge battery OUTSIDE the instrument: a. Remove battery through battery access door. b. Connect battery charger plug to battery jack and follow steps b and c above (C). E. Charge battery at temperatures above 45 degrees F for best results. F. Always disconnect charger from battery and AC outlet when not in use.
7. BATTERY MAINTENANCE INFORMATION. A. When instrument fails to operate normally the battery may be fully discharged. Recharging battery nightly will extend battery life. B. Store at room temperature 68 degrees F (20 degrees C) or below when not in use. NOTE: DO NOT STORE BATTERY IN A DISCHARGED STATE. RECHARGE AT LEAST EVERY 30 DAYS WHEN NOT IN USE.
8. FACTORY REPAIRS. Holiday Detectors returned to the factory for repairs should be sent TRANSPORTATION PREPAID. The Detector can be repaired and returned the same day it is received at the factory.
WHEN ORDERING PARTS FOR YOUR DETECTOR OR REQUESTING FURTHER INFORMATION ALWAYS GIVE THE DETECTOR'S SERIAL NUMBER.
D. E. Stearns
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