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Weatherex® Code Beacon Lamps were developed in 2004 by Don Northrop, former engineer at Duro-Test Corp. while under contract with WSI Lighting with the project managed by Randy Doremus, Sales and Marketing Director.
TWR Lighting of Houston, TX provided the certification testing in their certified lab so as to be approved by the FAA.
Per Certified Advisory Circular 150/5345-43E
Weatherex® was developed with the intent of providing the most robust, reliable, and cost effective Code Beacon lamp for the tower obstruction lighting industry.
The real cost of obstruction lighting maintenance is the labor to climb the tower. So if you reduce the number of times that you have to climb the tower especially the nonscheduled events caused by premature failure the excessive costs are reduced.
The minimum requirements to meet this goal were to:
Don spent many hours at the manufacturing facilities to ensure that every procedure was understood and precise per specification. In addition, he developed a final inspection process to ensure that any issues with the lamp would be corrected before the lamp was shipped out. These requirements were exceeded with the expert knowledge and capabilities of Don Northrop and utilizing the following materials and procedures.
The Standard-sized PS40 “hard-glass" bulb is made of Pyrex-like glass. Since the thermal expansion rate of this particular glass is much lower than the standard “soft” glass, it withstands greater thermal and mechanical shock– such as when a hot bulb comes in contact with water or the bulb is bumped against metal. The hard glass allows for higher lamp processing temperature, which can produce a cleaner lamp.
To achieve the optimal light for the preferred life of the bulb, the tungsten filament is designed with a variety of balancing criteria. Improved light efficiency is accomplished by closely coiling the filament turns to conserve radiated heat. The closeness of the individual turns is limited by physical touch and arcing between the turns.
The exact mixture of fill gas is chosen to minimize tungsten evaporation, reduce convection cooling, and prevent arcing between coil turns and wires. For safety purposes, the lamp fill pressure is controlled to provide a neutral lamp operating pressure.
Lead-In and Support Wires
Larger current-carrying wires, called lead-in wires, are used for dependable, low-electrical contact resistance for holding the hot coil ends. Where they pass through the glass, these nickel-plated, iron lead-in wires contain a special section of tungsten wire that
is compatible with the expansion of the glass and maintains the hermetic bulb seal. The thinner, coil support wires are made of molybdenum, which withstands contact with the high temperature of the lit filament. The springiness of the wires is tuned to suppress vibrations of the entire clamped filament and enable it to move in unison during shocks common during shipment and operation of the lamps.
The Brass, two-piece, pre-focus base allows precise centering of the filament when the lamp is completed. A minimum amount of high temperature solder connects the base to the base eyelet. The flux is removed to prevent possible corrosion or “welding "of the base to the receiving socket.
A getter is material which absorbs gaseous impurities from the inert lamp fill gas. It works much the same way that an open box of baking soda does when it is placed in a refrigerator to absorb odors. Once open, the baking soda can only hold a limited amount of odor. Similarly a getter must be placed within a lamp in a sufficient quantity and in the correct location to be effective throughout the lamp’s life
The Weatherex® brand uses an exclusive combination of zirconium-aluminum alloy getters. First, a fine granular mixture is painted onto the metal lead wire structure, beginning close to the filament and leading away to the cooler base of the lamp. Next, two ST101 high temperature getter tabs are welded onto the lead wires at different locations. This is done to optimize the getter action of the tabs for base up and base down burning. The ST101 getter is the optimum alloy ratio for absorption of hydrogen and carbon dioxide under the most severe conditions.
Each of these getters are designed to withstand lamp-processing temperatures and become active at lamp light-up. Initially the getter near the filament gobbles up the residual hydrogen, oxygen, and carbon trace gases from the internal lamp atmosphere.
During hours of burning, hot metal parts, as well as the bulb glass, liberate molecules of water. These molecules then breakup into hydrogen and oxygen on the hot tungsten filament. Left unchecked, these trace gases will gnaw away the filament and lead to early lamp failure. Commonly, this process is referred to as the “water cycle”. The getter intercepts the trace gases and permanently removes the impurities from the lamp atmosphere, allowing the lamp to age properly.