valutazioni - 4, GPA: 3.8
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Listed below are con-tion involving electricity must be grounded to earth ditions which could occur during start-up and operation. to eliminate shock hazard. 1. USE THE RIGHT HEAT TRANSFER FLUID DO read manufacturer’s technical bulletins and instructions carefully. Some heat transfer fluids may ignite or burn spontaneously if not properly used. Chromalox Fluid Heat Transfer Systems are designed for a particular heat transfer fluid or a class of heat transfer fluids. If you are not sure you are using an accepted heat transfer fluid, check with your local Chromalox sales and application engineering office listed on back cover or consult Chromalox Bulletin PQ301 for the correct heat transfer fluid. DO NOT mix heat transfer fluids unless authorized and approved by 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 manufacturer to determine the following. A. Is the new fluid compatible with the old? B. What is the recommended cleaning method to remove the old fluid, its sludge, or any deposits remaining in the system? C. Does the fluid manufacturer have a reclaiming service for used fluid? Do they have a recommended procedure for disposal of used or old fluid? CAUTION: To avoid possible damage to the heaters do not energize the heater unless the system is filled with fluid. 2. PIPE STRAIN DO provide for expansion and contraction of process piping and connections to the system. Piping strains can cause pump and motor mis-alignment, excessive wear on pump body, bearings and stuffing box packing or mechanical seal and will eventually cause failure of the pump and system. Piping should be properly supported so pump can be removed without changing the position of the piping. If piping moves when the pump is removed, pump malfunction is probably due to stresses and twisting caused by the piping. These stresses will multiply when the system is hot due to thermal expansion. 3. PIPING RESTRICTIONS DO provide sufficient cross sectional area in the process piping connections equivalent to the system pipes. In order to prevent undue pressure drop, maximum velocity in all piping should be less than 10 feet per second. DO NOT use process piping connections smaller than the pipes used in the system. If there is a high differential pressure between the inlet and outlet of the heat transfer system at operating temperature, this is probably due to a piping restriction. A continuing high differential pressure can cause excessive wear on the pump and pump stuffing box packing or mechanical seal and will eventually cause premature failure of the pump. The major causes of restrictions are: A. Inlet and outlet pipes smaller than provided on the system. B. Piping many processes in series with one another. To reduce the pressure drop of the system, equipment should be re-piped in balanced parallel flow. © 2010 Chromalox, Inc. 3. PIPING RESTRICTIONS C. The use of globe valves in the system. Globe valves have a much higher pressure drop than gate valves. Therefore use globe valves only for balancing parallel flows. D. Small inlet and outlet connections on customer’s process. Examples being: 1. The use of small rotary unions on roll applications. These should be sized properly for the actual pumping rate to give minimum pressure drop. 2. Small inlet and outlet nozzles on jacketed vessels or the use of an agitating nozzle on the inlet of a jacketed vessel. These should be sized properly for the pumping rate to give a minimum pressure drop. 3. The passageways or coring of a platen manifolded in series. These should be re-manifolded for parallel flow to give a minimum pressure drop. DO provide for bypass of oil when using pneumatic or electrically operated process valves. System damage may occur if process piping return lines are restricted or blocked by closed valves. 4. PIPING GENERAL DO NOT use Magnesium bed or porous insulations which can absorb oil. When oil soaked, these insulations may ignite spontaneously and burn at temperatures as low as 400°F. DO NOT permit leaks of any heat transfer fluid to continue unat tended. Periodic inspection of piping and insulation is essential. DO NOT insulate expansion tank lines or the expansion tank. These components must be kept cool and below 130°F for most heat transfer oils. (See #6 Expansion Tank Location) DO NOT insulate flanges, valves or other connections which may leak without being observed. DO NOT use screwed pipe connections on any piping over 1 inch diameter. Use flanges for connections with spiral wound or Grafoil® gaskets. DO NOT use Teflon tape or pipe seal on threaded connections on hot oil systems. Use Copalite® or SilverSeal® or other high temperature sealants compatible with heat transfer oils. DO check all vent tubes, purge valves, and bypass relief valves at least once a month. All heat transfer oils oxidize in the presence of ai...