![]() Protection from thermal effects is best provided by covering the gauges with a layer of insulating material such as Polystyrene foam or fiberglass. Therefore, always shield strain gauges from direct sunlight. If sunlight is allowed to impinge directly onto the gauge, it could elevate the temperature of the wire above the surrounding steel and cause large changes in apparent strain. However, this is only true if the wire and the underlying steel structure are at the same temperature. ![]() This means that no temperature correction for the measured strain is required when calculating load-induced strains. If attached to a steel structure, the thermal coefficient of expansion of the steel vibrating wire inside the instrument is the same as that for the structure. Doing so will cause the instrument cables to pick up the frequency noise from the power cable, and this will likely make obtaining a stable reading difficult.Ĥ.6 Protection From Sunlight and Temperature Changes Cables should never be buried or run with AC power lines. Apply a coat of paint over the primed areas.īe sure to install instrument cables as far away as possible from sources of electrical interference such as power lines, generators, motors, transformers, arc welders, etc. Be sure to spray beneath the coil housing, if applicable do not worry if the primer also coats the instrument.Ĥ. It is important to completely cover mounting tab edges, paying attention to where the tab is under the instrument. The idea is to protect substrate weld points. Spray self-etching primer (available locally) over mounting tab areas and all exposed bare metal areas. Mask off the areas where spot welds are needed.ģ. The glue will wick into the gap between the mounting tabs and the substrate and provide the first line of defense.Ģ. ![]() Apply several drops of cyanoacrylate adhesive to the edge of all spot welded mounting tabs. geokon recommends you follow this procedure:ġ. Stainless steel instruments will not corrode, but the substrate can corrode, especially at weld points, unless they are covered by a waterproofing layer. It is imperative that installation weld points, if any, be protected from corrosion. (The geokon cover plate has a stamped knockout which, when removed, provides a hole for connecting the conduit connector.) ) The conduit can be connected via conduit bulkhead connectors to the cover plates. (Flexible conduit is available from geokon. This is best accomplished by putting the cable inside flexible conduit and positioning the conduit in as safe a place as possible. The cable should be protected from accidental damage caused by moving equipment or fly rock. Cables must be restrained using welding studs, to which the cables can be tied at three-meter intervals.įigure 10: Cover Plate Installation, Side View Note: It is not necessary to use continuous welds tack welding is sufficient as long as it holds the angles or channels firmly in place. To accomplish this, leave windows in the steel over the gauge locations. To avoid damaging the cables, the protection should be welded on before the gauges and cables are installed. Gauges can be further protected by welding cover plates composed of 101 x 38 mm (4" x 1.5") channel iron or 64 mm (2.5") or larger angle iron over the top of the gauges. Alternatively, use a connector to plug directly into the readout box or to a receptacle on a special patch cord. Terminate a cable by stripping and tinning the individual conductors and then connecting them to the patch cord of a readout box. ![]() Contact geokon for splicing materials and additional cable splicing instructions. When properly made, this type of splice is equal or superior to the cable in strength and electrical properties. Splice kits recommended by geokon incorporate casts that are placed around the splice and are then filled with epoxy to waterproof the connections. Always maintain polarity by connecting color to color. When splicing, it is very important that the shield drain wires be spliced together. The cable used for making splices should be a high quality twisted pair type, with 100% shielding and an integral shield drain wire. Contact geokon for specific application information.īecause the vibrating wire output signal is a frequency rather than a current or voltage, variations in cable resistance have little effect on instrument readings therefore, splicing of cables has no ill effects, and in some cases may in fact be beneficial. The interior panel of the terminal box can have built-in jacks or a single connection with a rotary position selector switch. These allow many instruments to be terminated at one location with complete protection of the lead wires. Terminal boxes with sealed cable entries are available from geokon for all types of applications.
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