Chromalox PQ410-4 User's Manual
Contents
1. Chromalox SERVICE MANUAL SERVICE REFERENCE omision 4 secron SALES REFERENCE Supersedes PQ410 3 PQ410 4 161 048978 001 pate JULY 2009 Electric Fluid Heat Transfer Systems GENERAL This Service Manual is furnished as an aid to help start up and service 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 earth to 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 spontaneously if 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 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 manufac turer to determine the following A Is the new fluid compatible with the old B What is the recomm2. e from a packed pump is unacceptable in the application mechanical seal pumps are available at extra cost Contact factory 10 OPERATING ABOVE THE MAXIMUM ALLOWABLE TEMPERATURE OF THE HEAT TRANSFER SYSTEM OR HEAT TRANSFER FLUID DO NOT attempt to operate any heat transfer system or heat trans fer oil at temperatures higher than those recommended by the man ufacturer Chromalox heat transfer systems are designed for a particular maximum temperature If you do not know this design tempera ture check with the Chromalox factory or consult the individual instruction sheet for that system Exceeding the designed tem perature of the heat transfer system will void our warranty 11 The following are the major causes of insufficient heat A Low voltage B Blown fuse in heater circuit CAUTION Hazard of Electrical Shock Make sure all electrical power is disconnected before servic ing or replacing any electrical component C System too small for application not enough kW 1 Increased work load 2 Changed product or process 12 Leaking pipe joints can be caused by poor threads using the wrong or old gaskets and unsupported piping New gaskets should be used whenever a flanged pipe joint is made A good rule of thumb for systems operating above 350 F is to use flanged or welded connections on all pipe larger than 3 4 On high temperature systems threaded pipe will loosen with heat ing and cooling of system and i
3. eat transfer fluid to process See No 3 Piping Restrictions Thermostat set too low Piping or process not insulated This is a common fault The piping in heat transfer systems is shipped from the factory uninsulated only the heating chamber is insulated The piping in the heat transfer system should be insulated at the same time the piping from the system to the process is insulated E F MISCELLANEOUS PROBLEMS 3 Misalignment of pump will cause high leakage of oil pack ing type stuffing box and complete failure of mechanical seal type 4 Unusually high back pressure at high temperature C Pump bearing failure 1 Misalignment 2 Cavitation for causes of pump cavitation see sections 3 4 and 9 3 Excessively high pressure at operating temperature Can be caused by incorrect or poor quality heat transfer fluid Water in a heat transfer fluid can also cause high pressure D Spillage from expansion tank 1 Tank too small to accept expansion of liquid in system 2 Expanding pocket of air or steam in system forcing heat transfer fluid to back up into expansion tank E Sludging of heat transfer fluid is caused by either too high a heating element temperature or improper materials used in cus tomer s piping or process DO NOT use brass valves or fittings Generally speaking on oil type systems no copper or copper bearing alloys should be in contact with the heat transfer fluid START UP SUPERVISION Contac
4. ended 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 stress es 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 out let of the heat transfer system at operating temperature this is probably due to a piping restric
5. ill cause the pump to vapor lock due to insufficient NPSH net positive suction head On hot oil heat transfer systems this pressurizing is usually done with nitrogen as this eliminates the possibility of the hot fluid coming in contact with oxygen thus reducing the possibility of oxidation extending the life of the heat transfer fluid This pressure should be 5 10 PSI above the vapor pressure of the heat transfer fluid at its operating temperature 7 EXPANSION TANK LOCATION DO NOT pressurize expansion tank or system unless proper safe ty relief valves are provided WARNING If expansion tank is to be pressurized then it must be equipped with safety relief valve s If this pressure exceeds 15 PSIG then the heat transfer system and expansion tank should be ASME coded DO NOT mount expansion tank directly on top of system unless absolutely necessary If mounted on system provisions must be made for cooling of the expansion tank line Maximum safe oper ating temperatures are reduced when expansion tank is mounted on system unless positive suction pressure of 2 to 3 psig is main tained on pump SYSTEMS MOUNTED ABOVE PROCESS EQUIPMENT Ceiling or Platform mounted When mounting system above process equipment check to be sure the pump will not be vapor locked The cause for vapor lock is insufficient NPSH net positive suction head This problem is particularly prevalent on systems with centrifugal pumps but also can appear
6. ion 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 tem perature sealants compatible with heat transfer oils DO install bleed valves on all process piping The presence of air in the system is indicated by a knocking or hammering of the pump Air bleed valves should be provided at all high points in the system and every place where the heat transfer fluid flow drops in the vertical plain These are the places where air pockets will form The presence of water does not apply to water or water glycol systems in the system would not normally be noticed until a tem perature above 212 F is reached Its presence would be indicated in exactly the same manner as air in the system Follow the air removal procedure CAUTION During the initial start up operation the liquid level in the expansion tank must be checked DO mount expansion tank 15 feet above system Mount the expansion tank so it is the highest point in the sys tem and if possible at least 15 foot above the height of the pump To safeguard employees and equipment run the vent line either out of the building or down into a 55 gallon drum This vent line
7. n off switch in off position Turn switch to on Process control ITC 1 set too low No oil flow Set process control to desired temperature See items pump noisy see O insufficient suction pressure see J high discharge pressure see K Process piping too small or restricted Check process piping check heat transfer area of platen etc Heater fuses blown Check and replace fuses Heater elements burned out Excessive operating pressure over 40 psig Check continuity and resistance of elements See K Packing gland loose Check and adjust packing gland nuts per manufacturer s recommendations Wrong pump specified Use mechanical seals or sealless pumps where no oil leaks can be tolerated Improper cooling of seals Rough handling during shipment Expansion and contraction due to temperature has loosened connections Mechanical seals on pumps should be water cooled over 350 F Failure to do so will cause seal failure and leaks Check piping and flange alignment retighten and torque all bolts to specifications Check all flange bolts and connections retighten and torque to manufacturer s specifications Wrong gasket materials 5 Replace gaskets as necessary use spiral wound or Grafoil gaskets 14 STANDARD HEAT TRANSFER SYSTEM TROUBLE SHOOTING CHART Problem Insufficient suction pressure 0 or vacuum pump noisy gauges vibrating discharge pressure l
8. n time will leak Excessive leakage at stuffing box of pump 1 Packed type normal leakage rate is approximately five 5 drops per minute when cold 1 2 when at operating temperature Note Improper tightening of stuffing box gland will always cause abnormal leakage and possible shaft damage see Instruction Sheet for unit 2 Mechanical seal type water cooling of mechanical seals is recommended when operating over 350 F Most types should not leak either water or oil However some water cooled high temperature seals are designed to leak steam or water at a constant rate DO NOT connect cooling water to flush ports of mechanical seal pumps Water will be forced thru the seals and contaminate the oil Check manufacturer for proper connections 13 Factory trained personnel are available upon request for those customers who are unfamiliar with the initial start up 4 Exceeding the temperature limits of the heat transfer fluid will cause its thermal breakdown or degradation This will result in the formation of sludge in the system and carbon on the heating elements and eventually cause pump and heater failure If you do not know this maximum temperature check with the fluid manufacturer WARNING In hazardous or explosive areas the pipe surfaces of oil type heat transfer systems could achieve temperatures higher than allowed for Class I Group D Division I INSUFFICIENT HEAT D Restriction in flow of h
9. nd reset Pressure switch not closed Switch set wrong See N Set pressure switch to approximately 5 psi over suction gauge pressure Pump running backwards Check pump amp motor rotation see arrow on motor reverse phase lead on circuit breaker Not enough or no fluid in system Check fluid levels in expansion tank make sure all valves are open Pump cavitating Air or steam in system See O Bleed system periodically until all air or stem is removed Insufficient bleed valves in process piping to remove trapped air Contaminated oil Change oil Pump damaged by overtightened packing gland Replace pump Insufficient suction pressure Limited Warranty Suction pressure should be 4 5 psig Please refer to the Chromalox limited warranty applicable to this product at http www chromalox com customer service policies termsofsale aspx Chromalox PRECISION HEAT AND CONTROL 2150 N RULON WHITE BLVD OGDEN UT 84404 Phone 1 800 368 2493 www chromalox com
10. on systems with positive displacement pumps The things to check when a system is mounted above the process equipment are as follows A Piping Eliminate all unnecessary turns and restrictions in the return piping which could cause a vapor lock DO NOT allow pump to hammer or cavitate Excessive vibration will damage pump and may break pump castings CAUTION All pump and motor mounts and motor belt should be checked and tightened if necessary These sometimes loosen dur ing transit Belt Driven The belt has been properly aligned and adjusted for the proper deflection prior to shipment from the Chromalox factory The proper deflection is 1 4 Direct Coupled The pump and motor on each Chromalox heat transfer system is factory aligned prior to shipment However as recommended in our instruction sheet on each particular heat transfer system the pump and motor could become misaligned in transit and therefore should be realigned in the field after the unit has been permanently set in place Misalignment can cause wear on the pump shaft packing or mechanical seal and bearings It will cause excessive stuffing box leakage and will eventually cause complete failure of the pump and in turn the system To check alignment A Place a straight edge across the coupling it should be in full contact with both rims at the top bottom and both sides Rotate coupling by hand and repeat this check 9 Pumps with packed stuffing box o
11. ow below 20 psig High discharge pressure over 40 psig pressure gauges fluctuating rapidly pump noisy expansion tank normal system operating on bypass relief valve Expansion tank overflows or burps over 220 F Control relay 1 will not close Pressure switch will not close Pump noisy and or cavitation System temperature too high for oil causing vapor lock Corrective Action See fluid manufacturer s data for maximum oil temperature Vapors lock due to steam or air in oil Bleed air amp steam from system change oil if problem continues Net positive suction pressure too low Raise expansion tank to increase suction head static head should be 4 5 psig See expansion tank location No 6 Strainer plugged Remove and clean strainer Valve closed System piping blocked or restricted Check all valves Check all valves check strainer Process piping blocked or restricted Steam or water in oil Check process piping sizing check for closed valves or improperly installed automatic valves check all bleed valves for air or steam Bleed system change oil Expansion tank too low Expansion tank should be mounted 15 ft above system Expansion tank line too short Lengthen expansion tank line to cool oil and provide cold oil seal Tank too small for system Over temperature control open Check volume on process piping Set thermostat above process temperature a
12. r seals may require adjust ment during system start up Packed seals are designed to leak some oil for proper lubrication of the pump shaft Drip pans and drain connections are provided on these pumps to contain the oil and allow convenient removal Packed pumps will frequently leak oil at start up until the sys tem reaches operating temperature and the seals seat on the shaft 3s B The expansion tank should be connected into the pump suction line and be located high enough to create the necessary NPSH See No 6 If the expansion tank cannot be elevated then it should be pressurized with air or nitrogen to obtain the neces sary NPSH This will create a positive head on the pump and prevent the heat transfer fluid from flashing into vapor at the pump suction when the system is operating at temperatures equal to or exceeding the vapor temperature of the heat trans fer fluid PUMP ALIGNMENT B Check the ends of the meshed teeth on the coupling jaws with a feeler gage The ends of the teeth should be equidistant around the circumference of the coupling Do not rotate shaft when making this check Allowance must be provided for pump shaft and motor shaft expansion Figure 1 PUMP PACKING ADJUSTMENT When system reaches temperature tighten the two packing gland nuts evenly approximately 4 turn at a time until the shaft seal leaks 1 to 2 drops per minute Do not overtighten or shaft damage will occur Note If normal oil leakag
13. should be a minimum of 4 internal pipe size AIR WATER OR FOREIGN LIQUID PIPING RESTRICTIONS These should be sized properly for the pumping rate to give a minimum pressure drop 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 electrical ly operated process valves System damage may occur if process piping return lines are restricted or blocked by closed valves PIPING GENERAL 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 air and sludge can block critical piping Blocked vent tubes may cause excessive system pressures and or an explosion DO retighten all bolted connections and joints at operating tem perature Joints will expand and leak as they get hot Check all threaded connections on controls gauges etc for leaks DO vent all systems operating at atmospheric pressure properly Vents must be rigid metal piping terminating outside the building or into a suitable container The vent line should never be made of plastic rubber or other low temperature material and should be inch or larger pipe WARNING Oil saturated insulation on piping may ignite spontaneously at elevated temperatures Repair leaks and replace oil soaked insulation immediately IN THE HEAT TRANSFER FLUID contin
14. t your local Chromalox sales and application engineer list ed on back cover and request Bulletin PQ901 14 STANDARD HEAT TRANSFER SYSTEM TROUBLE SHOOTING CHART Problem Power light off Power light on pump will not start Power light on pump light on motor not running Power light on pump light on motor running pump not running Power light on pump light on motor running pump running heat will not come on Insufficient heat Pump packing gland leaking System leaks when filling System leaks at temperature and after cool down Main power feed off Corrective Action Turn on main power Circuit breaker off Turn on circuit breaker Control transformer Primary fuse blown Secondary fuse blown Transformer bad Replace fuse Replace fuse Check and or replace Pilot light blown Float switch open Replace bulb Add oil to system If no float switch jumper terminals 4 amp 5 Motor overloads tripped Reset overloads check running current Motor starter bad Motor fuse blown Check motor starter coil Replace fuse check motor overloads Motor burned out Broken belt Replace motor check motor for overload Check and replace belt Broken coupling Check and replace coupling Pump jammed by slag or foreign object Control relay 1 not closed Turn off system and rotate pump by hand if jammed disassemble and clean pump Check and clean strainer See M Heat o
15. tion A continuing high differential 2010 Chromalox Inc pressure can cause excessive wear on the pump and pump stuffing box packing or mechanical seal and will eventually cause prema ture 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 3 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 Small inlet and outlet nozzles on jacketed vessels or the use of an agitating nozzle on the inlet of a jacketed vessel 4 DO NOT use Magnesium bed or porous insulations which can absorb oil When oil soaked these insulations may ignite sponta neously 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 Expans
16. ually This level should not exceed the three quarter mark on the glass nor drop below the one quarter mark Note If abnormal expansion of fluid is detect ed this is probably due to a pocket of air or steam still present in the system Check all bleed valves If problem continues de ener gize pump and check bleed valves Foreign liquids in the heat transfer fluid may not cause trouble immediately However after this system has been in operation for a period of time at the normal operating temperature the foreign liquid could cause a chemical change in the heat transfer fluid which could lead to sludging the formation of carbon on the heat ing element and eventually failure of the heating element and pump EXPANSION TANK LOCATION CAUTION To avoid possible rupture of expansion tank due to pressure vent line should be checked on a regular basis to be sure it is always open to the atmosphere Failure to do so may result in rup ture of the expansion tank or other parts of the sys tem causing injury or hazard of fire Note If the expansion tank cannot be mounted above the highest point in the system or if the system is going to operate above the boiling temperature of the heat transfer fluid the expansion tank will have to be pressurized with air or nitrogen This eliminates the possibility of heat transfer fluid flashing into vapor in the heater at the point of high velocity in the system or at the suction of the pump which w
Download Pdf Manuals
Related Search