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SERVICEMANUAL

(Supersedes PQ410-3)

PQ410-4

161-048978-001NOVEMBER, 19854CES

Electric Fluid Heat Transfer Systems

GENERAL

This Service Manual is furnished as an aid to help start-up andservice Chromalox Heat Transfer Systems. Listed below are con-ditions which could occur during start-up and operation. CAUTION: Hazard of Electric Shock. Any installa-tion involving electricity must be grounded to earthto eliminate shock hazard.

1.USE THE RIGHT HEAT TRANSFER FLUID

DO read manufacturer’s technical bulletins and instructions care-fully. Some heat transfer fluids may ignite or burn spontaneouslyif not properly used.Chromalox Fluid Heat Transfer Systems are designed for a par-ticular heat transfer fluid or a class of heat transfer fluids. If you are not sure you are using an accepted heat transfer fluid, checkwith your local Chromalox sales and application engineering office listed on back cover or consult Chromalox Bulletin PQ301for the correct heat transfer fluid. A. Is the new fluid compatible with the old? B. What is the recommended cleaning method to remove the oldfluid, its sludge, or any deposits remaining in the system? C. Does the fluid manufacturer have a reclaiming service for usedfluid? Do they have a recommended procedure for disposal of used or old fluid? CAUTION: To avoid possible damage to the heatersdo not energize the heater unless the system isfilled with fluid. DO NOT mix heat transfer fluids unless authorized and approvedby the fluid manufacturer.All heat transfer fluids are not compatible with each other,whether made by the same manufacturer or a different manufac- turer. If you plan to switch fluids, check with the fluid manufac-turer to determine the following. DO

2.PIPE STRAIN

provide for expansion and contraction of process piping andconnections to the system. Piping strains can cause pump andmotor mis-alignment, excessive wear on pump body, bearings and stuffing box packing or mechanical seal and will eventually causefailure of the pump and system.Piping should be properly supported so pump can be removedwithout changing the position of the piping. If piping moves whenthe pump is removed, pump malfunction is probably due to stress-es and twisting caused by the piping. These stresses will multiply when the system is hot due to thermal expansion. DO

3.PIPING RESTRICTIONS

provide sufficient cross sectional area in the process pipingconnections equivalent to the system pipes. In order to preventundue pressure drop, maximum velocity in all piping should beless than 10 feet per second. A. Inlet and outlet pipes smaller than provided on the system. B. Piping many processes in series with one another. To reducethe pressure drop of the system, equipment should be re-piped in balanced parallel flow. DO NOT use process piping connections smaller than the pipesused in the system.If there is a high differential pressure between the inlet and out-let of the heat transfer system at operating temperature, this isprobably due to a piping restriction. A continuing high differentialpressure can cause excessive wear on the pump and pump stuffingbox packing or mechanical seal and will eventually cause prema- ture failure of the pump. The major causes of restrictions are:
© 1985 Wiegand Industrial Division, Emerson Electric Co.