Leveling the Magnetic Playing Field

When the Olivenhain Municipal Water District (OMWD) in Encinitas, Calif., recently mandated a rehabilitative painting of its massive 10 million-gallon, 300-foot diameter Black Mountain Norte potable water tank, it gave advance notice of ?removal/reinstallation? to the multitude of cell phone companies that used the tank as a telecommunications hub for their antennas and cable trays.

Since draining was required of the tank?s contents prior to epoxy coating and painting of its interior/exterior steel, the cable trays for the transmission lines had to be removed prior to the process. The request stated that this was required and essential in order to not adversely affect the tank?s protective coatings and seals.

The OMWD, which covers 48 square miles of northern San Diego County and serves a population of approximately 68,000 residents, received delayed response and coordination with the carriers to reinstall the equipment. In fact, painting had already begun and the carrier?s welders weren?t able to replace the tray holders that run the cable up the legs, sides and across the curvature of the tank, thus rendering re-welding a non-viable option. At this juncture, OMWD?s Operations Supervisor Eric Phillips was faced with finding a non-invasive solution to advance the project?s timeline for completion.

Phillips quickly sought council with the project?s Construction Manager, Chris Stump of Broken Arrow Communications (Carlsbad, Calif.), to develop a solution for the application with Metal & Cable Corp. Inc. of Twinsburg, Ohio, which had expertise in non-invasive magnetic design configurations. The ensuing invention was the patent-pending Magnemount cable/cable tray holding system that presented a non-penetrating
option to the welding and epoxy attachment methods that were delaying the project.

Designed to withstand winds up to 150 mph, the Magnemount system presented OMWD with a high-capacity magnetic solution to securely carry the cables and trays across and down the curvatures of the steel water tank. Most importantly, it presented no damage to the water tank?s interior/exterior surface; providing a fast, clean on-site installation that allowed the flexibility to remove-and-attach at will without welding.

Cable Tray Holding System Design/Assembly

Designed to conform to the varying curvature of steel water tanks via independently mounted magnets, the Magnemount system eliminated the need for Broken Arrow?s carrier installers to weld, cut cable trays or add additional hardware to accept the arc of the tank. This is accomplished by placing one Magnemount cable/cable tray mount on each end of every length of cable tray. The final system leverages the originally patented Magnemount attached to 304 grade stainless steel ?Unistrut.?

Furthermore, Stump worked with Metal & Cable Corp.?s President and Magnemount inventor, David Klein to provide specific revisions to the system?s unique combination of magnets, hardware and neoprene washers. According to Klein, ?The adjustments involved using longer hex head cap screws (up to 5 inches long) so the cable trays can adjust farther off the tank. These act like refrigerator leveling feet so the end of one tray can mate with the new end by adjusting the height of the acorn nut that supports the whole apparatus.?

Stump noted that, ?The new configuration made it even easier for our installers; once the Magnemount cable tray holders are placed on the tower it takes no more than one minute to make adjustments, if necessary. It also accommodates existing surface painting under the system on the water tower tanks and may eliminate the need to remove it during future painting processes.?

Results

Broken Arrow completed the first installation of the Magnemount system for national wireless carrier Cricket Communications Inc. of San Diego, Calif., in August 2010 using approximately 250 feet of cable tray and 100 Magnemount cable/cable tray holders in the installation. The OMWD has also required installers for all of the tank?s wireless carriers (including Verizon, Sprint and T-Mobile, etc.) to incorporate non-weld systems and all are in the process of implementing and installing these systems to meet compliance.

According to OMWD?s Phillips, ?This system is easy, flexible, maintenance-free and eliminates permanent welding. Also, with multiple wireless carriers on the tank it simplifies the logistics of coordinating whose tray goes where because the Magnemount is not a permanent weld and adjustments can be made ?on-the-fly.?

Broken Arrow?s Stump also noted, ?The system provides an outstanding alternative to welding, which is often not allowed by certain water districts. More importantly this magnetic solution allows for a much less invasive installation process, which provides cell phone companies with a viable option to present water municipalities who are averse to welding on their tanks. Ultimately, it?s a win-win for water districts, cell phone companies and the contractors performing the work.?

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