Electric Immersion Heaters
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electric immersion heaters electric heating and controls Table Of Contents Selection Guide . 1-3. Quick Ship Screw Plug Heaters . 4-8. Construction Features . 4 1” Screw Plug Heaters . 5 1-1/4” Screw Plug Heaters . 6 2” Screw Plug Heaters . 7 2-1/2” Screw Plug Heaters . 8 Stock Screw Plug Heater . 9 Screw Plug Heaters . 10-17. 1” Screw Plug Heaters . 10 1-1/4” Screw Plug Heaters . 11-12. 2” Screw Plug Heaters . 13-15. 2-1/2” Screw Plug Heaters . 16-17. Heater Options . 17 Flange Heaters . 18-28. Construction Features . 18-21. Water Heaters . 22-24. Oil Heaters . 25-26. Heater Options . 27-28. Over-the-Side Heaters . 29-31. Construction Features . 29 Heater Options . 29 Water Heaters . 30 Oil Heaters . 31 CSA Listed Explosion-proof Heaters . 32-35. Construction Features . 32 Temperature Code Calculations . 33 Water Heaters . 34 Oil Heaters . 35 Tank and Basin Heaters . 36-38. Pipe Insert Heaters . 36 Deep Tank Heaters . 36 Cooling Tower Heaters . 37-38. Control Panels . 39-41. Contactor Control Panels . 39 SCR Control Panels . 40 Cooling Tower Control Panels . 41 Thermostats and Accessories . 42-44. Special Purpose Heaters . 45-46. Bottom-Mounted Heaters . 45 Rectangular Flange Heaters . 46 Series 770 Flange Heaters . 46 Dimension Sheet for Screw Plug Heaters . 47-48. Limited Warranty . Back Cover Selection Guide Selection Guide Heater construction is selected on the basis of the following criteria: Calculating KW Capacity • Space Available for both elements and headers. If a great In general, KW capacity will be determined by one of two fac- deal of heat must be concentrated in a small volume, one tors: the heat required to bring the process up to temperature, heater with multiple elements should be used. If it is desir- and the heat required to maintain the process at operating able to distribute the heat over a large volume, multiple temperature. Both requirements must be calculated; heat- heaters should be installed at intervals along the vessel. ers are selected on the basis of the method that results in the higher KW rating. • Watt Density or watts per square inch of element surface area, compatible with the fluid heated and the maximum For assistance in calculating the KW capacity for your job, con- fluid temperature. See Table I for recommendations. The sult your local Heatrex representative. lower the watt density required, the larger the physical size of the heater. Watt Density And Sheath Selection • Structural Strength of the vessel, both for supporting the Watt density and sheath material are the two most critical fac- heater(s) and to maintain system pressure. tors affecting immersion heater life. Watt density (watts per • Controllability, to determine how closely the temperature square inch of heater surface area) determines heater operat- will be maintained. In addition to the selection of a control ing temperature for a given set of fluid conditions. Sheath system it is often necessary to stage the heater to achieve material similarly determines the rate of corrosion. Both vary good control. Distribution of heat also affects controllability. with fluid temperature. Table I has sheath materials recommended for each fluid and Application Factors temperature. Those with an “A” rating have the best corro- Carry-over - Avoid contaminating the process with chemicals sion resistance, a “B” rating indicates fair resistance. Where a carried over from other processes. This can be particularly range of watt densities are shown, the lower end of the range critical in plating and cleaning lines where parts may be dipped represents a more conservative design. successively in different solutions. The maximum watt density shown is 75 watts per square inch. Sludge - Be sure that heaters are located above the point of In some applications, even higher watt densities may be suit- maximum sludge buildup since sludge will insulate the heater able depending upon the details of the application (fluid veloc- from the solution and cause premature failure. ity, contaminants in the fluid, space between elements, etc.). Consult your local Heatrex representative if a higher watt den- Temperature - Control the process temperature as closely as sity is desired. possible. Excess temperature reduces heater life. Since we specialize in custom-built industrial heating equip- Heater Cycling - Match the heater wattage as closely as pos- ment, Heatrex can review your applications that are out of the sible to the actual load requirements to limit on-off cycling. ordinary, including heaters for immersion in fluids not shown Galvanic Action - Between the heater and adjacent metallic in the table. surfaces will cause premature heater failure and may similarly While Table I represents our most current knowledge, many corrode the tank. application factors are beyond our control. Thus, this table Maintenance - Routine heater maintenance will help prevent should be used only as a guide. Heatrex cannot be responsible small problems from becoming serious. Heaters should be for heater failures due to corrosion. examined at regular intervals for corrosion and scale buildup. Iron Content - In critical processes where no trace of iron can be tolerated, stainless steel heaters can be electropolished before installation. Headers - In some applications, the header material can be as critical as the sheath material. In those cases, specify the header to match the sheath and specify “welded joints” if the solution will attack silver solder. www.Heatrex.com 800-394-6589 Selection Guide Recommended Sheath Material Table I Recommended Recommended Sheath Materials Sheath Materials Max. Max. Boiling Fluid Boiling Fluid Watt Watt Fluid Point Temp Fluid Point Temp Density Density °F °F 6 °F °F 6 W.Sq.In. W/Sq.In. Copper Steel Steel 304 Stainless Steel 316 Stainless Monel 400 Titanium 800 Incoloy 600 Inconel Copper Steel Steel 304 Stainless Steel 316 Stainless Monel 400 Titanium 800 Incoloy 600 Inconel Acetic Acid 100 50-65 B A B 225 100 55-60 A A A (50%) 200 20-25 B A B 200 40-50 A A A Dowtherm-A 495 Acetic Acid 100 30-40 B A B 300 20-35 A A A 244 (100%) 200 10-15 B A B 500 3-5 A A A Acetone A A 100 A A A (100%) 200 A A A Dowtherm-E 356 Alcohol 300 A A A 117 110 5-7 A A (Butyl)1 350 A A A Alcohol 100 5-7 A A 200 A A A 1 173 (Ethyl) 150 3 A A 300 A A A Dowtherm-G 572 Alcohol 100 10-12 A A 400 A A A 152 (Methyl)1 150 5 A A 500 A A A Ammonia 200 30-40 A A A 5 120 10-12 B B A A Ethylene Glycol (Sat. Liquid) 392 300 20-30 A A A (100% Solution) Ammonia 390 5-10 A A A A A Chloride (50%) 200 35-45 B A A Gasoline1 100 40-55 B A A 405 300 15-25 B A A Aniline (Cracked) 363 200 30-55 B A A 400 3-6 B A A (Commercial)1 300 10-15 B A A 300 15.20 B A A Asphalt (Tar) 400 300 5-9 A A Glycerin1 554 500 3-5 B A A 100 20-25 A A 100 40-50 A A A Benzene 176 A Humbletherm 150 10-15 A A 300 40-50 A A A 500 720-950 500 30-40 A A A Calcium Chloride 200 100 20-25 B A (Aliphatic Oil) (30% Solution) 190 5-8 B A 700 5-12 A A A Caustic Soda 215 180 25-40 B Jet Fuel JP-4 A Chloroform 142 100 10-15 A A 100 15-20 A A A Kerosene 176 140 5-8 A A 150 5-10 A A A Diphenyl C12H10 610 600 10-15 A A A Methanol A A Oil (Paraffin) 572 400 15-20 A A A 1Lead sheath can be used satisfactorily with this solution up to a temperature of 250° F. 4Higher watt densities could be applied depending upon specific application. 2Inconel sheath can be used satisfactorily with this solution. 5Boiling point of ammonia at 14.7 PSI is 28° F and at 292.5 PSI. 3Copper sheath can be used satisfactorily with this solution. 6Incoloy can always replace steel or stainless steel. 2 www.heatrex.com 800-394-6589 Selection Guide Recommended Sheath Material Table I Recommended Recommended Sheath Materials Sheath Materials Max. Max. Boiling Fluid Boiling Fluid Watt Watt Fluid Point Temp Fluid Point Temp Density Density °F °F 6 °F °F 6 W.Sq.In. W/Sq.In. Copper Steel Steel 304 Stainless Steel 316 Stainless Monel 400 Titanium 800 Incoloy 600 Inconel Copper Steel Steel 304 Stainless Steel 316 Stainless Monel 400 Titanium 800 Incoloy 600 Inconel 100 30-35 A A 100 A A A 300 15.20 A A 4 Oil (Vegetable) 550 Therminal 60 200 A A A 400 5-10 A A (Max. Bulk 741 300 25-30 A A A 550 2 A A Temp. 600° F) 500 A A A Oil (Fuel) 600 A A A 200 15-20 A A A 1&2 220 200 5-12 A A A 100 25-30 A A A 5&6 4 160 5-12 A A A Therminal 66 300 25-30 A A A Bunder B&C (Max. Bulk 745 500 25-30 A A A Oakites Temp. 650° F) 600 20-25 A A A 210 210 30-40 A A A 20,23,24,30,51,90 650 10-15 A A A Oil (Lubricating) Therminol 88 SAE 10-20 350 250 15-20 A A A (Max.