Service Bulletin: SB 056.1
Subject: Tubular Heater Installation
An improved method of installing bottom station tubular heaters has been developed so as to minimize heater failure caused by hot spots,extreme internal temperatures, and mechanical failure caused by poor heater retention.
By using a product known as Heat Transfer Cement T-63 manufactured by Thermon manufacturing Company, 100 Thermon Drive, San Marcos, Texas 78666, U.S.A. (Phone 512-392-5801/Telex 77-6461). This material is intended for high temperature applications, such as packing high temperature electrical resistance heaters. When a tubular heater is imbedded in this material inside the heater holder ring excellent heat transfer is obtained with minimum internal temperature demand placed on the heater itself. The higher the wattage of the heater used the more important it is to have total heater body contact to the body (heated ring) to be heated. The thermal cement fills all air voids or gaps between the heater body and the machined groove in the holder.
To install pack the Holder groove about half full with Transfer Cement T-63. Press the Heater into the groove and pack cement around the rest of the Heater and trowel flush with the back of the Holder. Mount the Heater Holder Ring over the back of the Holder.
Using temperature control unit and regulated 120 volt power source set the controller for 100OF (400C) for one hour. Then raise temperature to 130&Mac251; F (55&Mac251; C) for thirtT minutes and then raise temperature to 160&Mac251; F (70&Mac251; C for twelve hours. The cement is then cured and the assembly can be installed at any time in the station assembly. when replacement is necessary use the front tapped holes in the Holder Ring as jack screws to push the heater and cement out. Any remaining cement may be easily removed after soaking in water.
With tubular heaters installed by this method and the heater leads supported as described in Service Bulletin 54-10-78 and 56-11-78 heater life will be greatly extended.
For those who may wish to purchase spare components for this assembly specify Heater Holder Ring part number, tubular heater, and tooling heated ring referencing the cup number.
It is necessary that all installations use the described heater support and retention methods in order that machines requiring heated bottom stations may perform satisfactorily.