Circulation

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Section Page

Circulation HeatersOverview

• In-Line or Recirculating

• Water, Solutions, Oils, Steamand Gas Heating

• High Efficiency

• Packaged Heater, Vessel andControl

• ASME Certification

• Custom Designs

Applications

Typical applications include heating water, oils,heat transfer fluids, mild and corrosive fluids,gases and steam. Heaters can be mounted onthe side of tanks, inserted into closed-loopsystems or installed in-line for processheating.

Water Heating — Washrooms, dish washingand rinsing, process water heating, jacketedkettles, hot water storage tanks and hydronicheating systems.

Freeze Protection — Water cooled engines,stand pipe water tanks for fire protection, oilsump heaters.

Heat Transfer Oil Heating — Process kettles,molding dies and platens, mixing and blendingmills, closed-loop heat transfer systems forasphalt and heat sensitive materials.

Fuel Oil Heating — Preheating to pumpingviscosity, preheating for delivery to burners.

Steam, Air and Gas Heating — Steamsuperheating, air preheating for processequipment.

Special Features

Consult your Local Chromalox Sales office formore detailed information on many specialfeatures, larger kilowatt heaters and skidmounted circulation heater systems.

Section Outline

Circulation heaters are packaged unitsdesigned to heat a flowing medium using in-line or side-arm piping configurations.Complete units consist of built-in heatingelements, a heating chamber, thermostat and/or sensors (stock units), insulation, insulationjacket, mounting brackets and inlet and outletconnections.

Circulation heaters offer high efficiency sinceall heat is generated within the solution. Fluidsare directed past the heating elements givingfast response and even heat distribution.

A wide selection of kilowatt ratings, materials,vessel sizes, terminal enclosures, controlfeatures and mounting methods are availablefor all types of heating requirements.

SCR and Contactor Control Panels availablefor integral or remote mounting. ConsultControls section for details.

Application Engineering

The Chromalox sales and service organizationhas the technical capabilities and equipment tosatisfy virtually any circulation heatingapplication and to assist you in calculatingrequirements for the more common heatingprocesses.

The Chromalox organization is the mostexperienced and diversified manufacturer inthe electric heating business. Whatever yourheating requirements, you can depend on thetechnical know-how of your Chromalox fieldrepresentatives. Backed by the highly skilledengineers and modern manufacturingfacilities, Chromalox field sales engineers canhelp determine your requirements and provideyou with high quality equipment, properlyselected, sized and applied.

Features C-4Terminal Enclosures C-5Control Options C-6Clean Water Series C-7Oil Series C-16Steam, Air & Gas Series C-27Solution Water & Hi-Temperature C-34Gas SeriesCustom Engineering C-42

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Circulation HeatersSelection Guidelines

Typical Applications

Inline Heating — Where demands for heatedwater or oil are nearly constant, circulationheaters may be installed directly in the fluidline, eliminating the need for storage tanks andtheir related heat losses.

Closed-Loop Fuel Oil Heating — Require-ments may be provided by a number ofcirculation units individually adjustable totemperature and fluid flow, reducing electricaldemand on your utility bill.

Selecting a Circulation Heater

Selecting the proper circulation heatercomponent requires critical engineeringjudgement and careful evaluation of theapplication. After determining the heatrequirement for a specific heat application, theproper selection of the flange and vesselmaterial, heating element sheath material, andcorrect watt density is critical to achieve longheater life. The ultimate selection of equipmentis determined by the knowledge of the processand engineering acumen of the designer orplant engineer. Consult the Technical sectionof this catalog for circulation heater calcula-tions and guidelines.

Application Factors

Heater selection is influenced by the followingparameters.

1 The heated medium, viscosity, specificheat, density and corrosive properties.

2 The presence of contaminants in themedium.

3 The corrosion resistant properties of theheater sheath material.

4 The sheath watt density of the heatingelements — the watts per square inch, andthe flow rate of the heated medium.

5 The vessel design and material — pressureand temperature of the fluid being heated.

Corrosion Policy

Chromalox will not warrant any electric heateragainst failure by sheath corrosion if suchfailure is the result of operating conditionsbeyond the control of the heater manufacturer.It is the responsibility of the purchaser tomake the ultimate choice of sheath materialbased on his knowledge of the chemicalcomposition of the corrosive solution,character of materials entering the solution,and controls by which he maintains theprocess.

Circulation Heaters — Selection Guidelines

Water Clean Water pH6 to pH8 (Neutral) Copper 45 - 100 Galvanized SteelMild Solutions Process Water and Very Weak Solutions pH5 to pH9 (2 - 3%) INCOLOY® 45 - 86 Stainless Steel

Weak Solutions 5 - 6% INCOLOY® 45 - 75 Stainless SteelDemineralized, De-ionized or Pure Water — INCOLOY® 45 - 75 Stainless Steel

Corrosive & Mildly Corrosive Solutions 5 -15% INCOLOY® 20 - 25 Stainless SteelHigh Viscous More Severe Corrosive Solutions 10 - 25% INCOLOY® 20 - 25 Stainless SteelSolutions Severely Corrosive Solutions 30 - 60% INCOLOY® 10 - 20 Stainless SteelOil Low Viscosity Oils — Steel 20 - 25 Steel

Medium Viscosity Oils — Steel 10 - 20 SteelHigh Viscosity Oils (Fuel Oil) — Steel 5 - 15 Steel

Air, Gases Medium Temperatures to 750°F — INCOLOY® 20 - 25 Steel& Steam High Temperatures to 1400°F — INCOLOY® 10 - 20 Stainless Steel

Solution or Alkaline or Acid Content Sheath Watt Density VesselApplication Heater Type (Est. % by Volume) Material (W/In2) Material

3

Strainerand Pump

(when used)

Inlet fromStorage Supply

Outlet toApplication

Shut Off ValvePressure Relief Valve

Drain

DrainThermostatBulbs

Pressure Relief Valves

Outlet

To FuelOil Burner

Pump

From FuelOil TankSump

Strainer

Storage Tank

Return Line to Tank

Side Arm — Requirements of large storagetanks can be satisfied by using a number ofcirculation heaters, providing flexibility intemperature control and reducing powerdemand.

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Codes & Standards

ASME Certification to Sections I, IV and VIII,Division 1 — Chromalox is the leader inproviding ASME (American Society ofMechanical Engineers) certification forpressure vessel applications.

Underwriters Laboratories — UL Listingavailable for many circulation heaters. Consultyour Local Chromalox Sales office.

Canadian Standards Association — CSAcertification available including NRTL/C.

National Electrical Code (NEC) — AllChromalox circulation heaters are built to allowNEC installation requirements.

Special Features

Kilowatt Ratings — Large kilowatt circulationheaters (500 kW and above) are available assingle chambers or with multiple chambers inseries. Skid mounting and integral controlpanels are also available.

Vessel Construction — Chamber size availablein 10, 12, 14, 16, 18" and above for largerkilowatt capacities.

Pressure Ratings — 150, 300, 400, 600, 900,1,500 and 2,500 Lb. Class.

Materials — 304, 316, 321, 347 StainlessSteel, INCONEL® and more.

Thermocouples can be provided on elementsheath for overtemperature protection and/ormounted in the outlet nozzle for processcontrol.

Inlet and Outlet Nozzles — Available withflanged or threaded connections, smaller orlarger pipe sizes and different orientations.

Baffles mounted on element bundle insidechamber to increase fluid or gas velocity.

Terminal Standoffs in 4, 6 and 8" allow theterminal enclosure housing and the fieldwiring connection to operate at lowertemperatures in high temperature heaters.Standoffs are frequently used in heat transferand gas heating applications.

Mounting Saddles for horizontally mountedcirculation heaters.

Weatherproof Insulation Jacket for outdoorunprotected installations.

Circulation Heaters — Selection Guidelines

Clean Water Copper/Galv. 3 - 5 Oval Flange NWHA C-8Steel 3 - 18 Screw Plug NWHMT C-9

6 - 500 Flanged NWH C-10Copper/Steel 1.5 - 3 Booster NWHJR C-12or Brass

Clean Water INCOLOY®/ 0.5 - 40 Field Adjustable NWHSRG C-13& Oil Cast Iron NWHORG C-14

or GalvanizedPure Water & Stainless/ 3 - 18 Screw Plug NWHMTSS C-35Mildly Corrosive StainlessCorrosive & INCOLOY®/ 6 - 200 Flanged NWHIS C-36High Viscous Stainless 2 - 30 Reduced Watt Density NWHOIS C-37Solutions INCOLOY®/ 1.5 - 3 Non-Metallic Body CVCHS C-15

CPVCOil Steel/Steel 1.5 - 2.5 Oval Flange NWHOA C-17

Light 3 - 9 Screw Plug NWHMTO C-18Medium 1 - 9 Reduced Watt Density NWHMTOR C-19

3 - 120 Flanged NWHO C-2030 - 120 Baffled NWHOB C-22

Heavy 3 - 120 Reduced Watt Density NWHOR C-2320 - 70 Baffled NWHORB C-25

Fuel Oil 30 - 40 Suction, Pump Mount SHO C-26& AsphaltSteam, Air & Gas INCOLOY®/ 1 - 1.5 Oval Flange GCHAI C-28

Med. Temp Steel 1 - 9 Screw Plug GCHMTI C-291 - 9 Reduced Watt Density GCHMTIR C-30

3 - 350 Flanged GCHI C-31High Temp INCOLOY®/ 2 - 200 Flanged GCHIS C-38

Stainless 30 - 50 Baffled GCHISB C-380.5 - 3.0 Low Flow GCHCIS C-40

Pre-engineered Packages — Wired & Skid Mounted C-41ASME & Custom Engineering Specifications (SDS) C-42

Heater/Vessel kWApplication Material Rating Feature Model Page

Circulation HeatersSelection Guidelines (cont.)

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• Kilowatt Ratings from 0.5 kW(500 W) to Over 500 kW (500,000 W)

• Voltage Ratings to 600V

• Pressure Ratings from150 - 2,500 psig

• Temperatures to 1500 °F (815°C)

• Pipe Chambers 1 - 18" NPS (orLarger)

• Quality Heating Elements inScrew Plugs or Flanges for Easeof Installation

• Sheath Materials include Copper,Steel, Stainless, INCOLOY ® andINCONEL® to Suit Most Operating orCorrosive Environments

• Vessel Materials include CarbonSteel, 304 or 316 Stainless Steel,Non Ferrous Alloys and HighTemperature Plastics

• Terminal Enclosures for GeneralPurpose, Moisture Resistant andExplosion Resistant Applications

• Thermocouples and RTD Sensorsfor Process and OvertemperatureControl

• Wide Range of Mechanical andSolid State Electronic Controlsincluding Temperature Controllers

• Contactor or SCR Power Panels forClose Temperature Control (seeControls section)

• Vertical or Horizontal Mountingwith Mounting Lugs or SaddleSupports

• Available with High TemperatureStandoffs and Internal ElementBaffles

• Custom Designed SkidMounting,Multiple Chambers and IntegralControl Panels

• ASME Certification Section I, IVor VIII, Division 1

• UL, CSA and Other Third PartyApproval, Listing or CertificationAvailable on Many Models

Circulation HeatersFeatures

Basic Construction

Terminal Enclosures — E1 General Purpose,sheet metal, painted with red enamel, E2Moisture Resistant/Explosion Resistant, E3Explosion Resistant, E4 Moisture Resistant.

Controls — Stock and assembly stock NWH,NWHO and GCH circulation heaters, models -A,-MT, -3 and -6, are provided with a thermostatmounted on the heater.

Mounting — Small units supported by inletand outlet piping; larger units provided withmounting lugs for support.

Outer Jacket — Constructed of heavy gaugepainted steel sleeving which contains hightemperature thermal insulation to reduce heatlosses from heating chamber.

Heating Chamber — Pipe chambers (150 Lbwelded construction, standard) have a flanged

or threaded end to receive heater assemblyand are closed at the opposite end. Largerunits have drain connections to allow sludgeremoval. Inlet and outlet nozzles are providedfor circulation of fluid or gas through heaterchamber. Chamber material available in Steel,Galvanized Steel or Stainless Steel dependingon the application.

Heating Elements — Flange or screw plugmounted tubular type heating elementsoffered in Stainless Steel, Copper, Steel orINCOLOY® sheath to suit corrosive resistancerequirements.

Wiring Connections — All Chromaloxcirculation heaters are provided with internalwiring and power connections that are sized inaccordance with wiring tables in the NationalElectrical Code. For safe operation of theheaters, all external wiring should also be inaccordance with NEC, state and local codes.

Basic Construction

Terminal Enclosure

To Power Supply

Thermostat (type AR)

Outer Jacket

Heating Chamber

Heavy Duty Heating Elements

SedimentDrain Plug

Mounting Lugs

Pipe Inlet (Std.)

Insulation

Pipe Outlet (Std.)

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• E1 General Purpose

• E2 Moisture Resistant/ExplosionResistant

• E3 Explosion Resistant

• E4 Moisture Resistant

• Conduit Openings Matchedto the Number of Circuits

Circulation HeatersTerminalEnclosures

Applications

The versatility of electric heaters permitsthem to be used in almost any conceivablelocation indoors or outdoors, exposed to theweather. Chromalox provides a variety ofelectrical terminal enclosures to match theunique requirements of virtually anyenvironment.

Features

E1 General Purpose Enclosure — Suitablefor most indoor or protected commercial andindustrial applications.

E2 Combination Moisture Resistant andExplosion Resistant and E3 ExplosionResistant Enclosures — Type E2 and E3explosion resistant terminal enclosures areintended for use in hazardous locationsincluding:

• Class I Groups C & D, Div. 1 & 2

• Class I Group B1, Div. 1 & 2

• Class II Groups E, F & G, Div. 1 & 2

• Class III, Div. 1 & 2.

Type E2 terminal enclosures are providedwith gaskets and are suitable for outdoor orwet locations as well as hazardous areas.

E4 Moisture Resistant Enclosure — Suitablefor outdoor or wet locations. The terminalcovers are provided with water-tight gasketsto seal the electrical terminals and connectionsfrom the environment.

Special Requirements for ElectricHeaters & Terminal Enclosures inHazardous Locations:

Wiring — The proper use of Type E2 and E3terminal enclosures on electric heaters locatedin hazardous areas requires that all electricalwiring comply with National Electrical Code(NEC) requirements for hazardous locations.

Maximum Temperatures — Safe operation ina hazardous location requires the maximumoperating temperatures of all exposedsurfaces of the heater including temperatureson the outside of the vessel, piping, flanges,screw plugs, enclosures and other heatconducting parts be limited. The maximumsurface temperature permitted in anyhazardous location is determined by theflammable liquids, vapors or gases present.The end user or purchaser of the electricheating equipment is responsible for deter-mining the proper classification of an area andfor providing Chromalox with hazardous areaspecifications and requirements for properequipment design. (NEC Articles 500 and 501provide guidelines for evaluating andclassifying hazardous locations.)

Safety Devices — Approved pressure and/ortemperature limiting controls must be used onelectric heaters and heating elements toensure safe operation in the event of systemmalfunctions.

Note 1 — Class I Group B locations includeHydrogen gas. These areas require additionalconduit seals and thread engagement. Contactyour Local Chromalox Sales office for heatersand terminal enclosures suitable for Class IGroup B hazardous locations. Moisture Resistant, Type E4

typical for all heaters except Series 3

B

Typical Terminal Enclosures

General Purpose, Type E1

Explosion Resistant, Type E2/3for Series 3 heaters

Explosion Resistant, Type E2/3for Series 8 and larger

Explosion Resistant, Type E2/3for Series 6 heaters

A

B

B

B

No.Series Elements A B A B A B

3 3 4 3-1/2 4-1/4 5-3/8 4-1/4 5-3/86 6 6-11/16 3-1/2 5-3/4 6-15/16 3-9/16 6-3/4

18 18 9-13/16 5-3/8 9-1/2 10 10 5-11/1627 27 11-3/16 6-9/16 10-1/2 9-1/8 12 5-11/1636 36 13-3/16 6-9/16 12 9-1/8 12 6-5/1645 45 15-3/16 6-9/16 14 9-1/8 14 6-5/1672 72 17-3/16 6-9/16 18 10-1/8 18 7

108 108 19-3/16 7-7/8 20 10-1/8 20 7

Dimensions (In.)E1 General Purpose E2/3 Moist./Explos. Resistant E4 Moisture Resistant

Terminal Enclosure — Dimensions (Inches)

A

B

A

A

A

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• Wide Range of Mechanical andElectronic Control Options

• NEMA 1, 4, 7 and 12 Enclosures

• Process Controllers - Integral orRemote with the Sensor in theHeater Thermowell (AR Control)or in the Heater Outlet

• High Limit Controllers - Integralor Remote, Sensor in the HeaterThermowell (AR Control) orWelded to Element Sheath

• Type J or K Thermocouples(Std.) RTD’s and Other TypeThermocouples Available

• Mechanical and ElectronicControls can be Combined

• Magnetic Contactors for MultipleCircuits and High Amperages

Circulation HeatersMechanical & Elec-tronic Control Options

Applications

Mechanical and Electronic Controls &Thermal Sensors can be provided for allcirculation heaters for overtemperatureprotection for the heater and fluid mediumand/or for process control.

Control Selection Guidelines

AR Controls — Type AR bulb and capillarycontrols are standard on many stock heaterswith temperature ranges as indicated in theproduct descriptions. These rugged non-indicating controls are suitable for mostapplications. Optional temperature ranges areavailable. Consult the Controls Section fordetails.

Electronic Controls — Electronic processcontrols provide greater control accuracy andoperating system flexibility than is availablewith mechanical controls. Consult theControls Section for details.

Control Panels — Integral or remote mountedcontrol panels with electronic controls andsolid state (SCR) or contactor power control-lers can be provided using virtually anycombination of control devices. Consult theControls Section for details.

Overtemperature Protection —De-energizing the heating elements whensheath temperatures exceed recommendedlimits can prevent element damage and extendthe life of the heater. A thermal sensor can beattached to the element sheath for overheatprotection. Properly connected to a solid statehigh limit controller, the sensor will turn theheater off in the event of a low-flow or no-flowcondition. Type J thermocouples are recom-mended for liquid and type K for gas applica-tions.

High Limit Controls — Electronic high limitcontrols can be mounted on the heaterchamber with an overheat thermocouplewelded to heating element sheath inside thechamber. This arrangement provides protec-tion by shutting down the heater at a predeter-mined element sheath temperature. Optionalso available with thermocouple only, weldedor clamped to heater element sheath as shownabove.

Magnetic Contactors — Heaters utilizing twoor more circuits or with amperage draw thatexceeds the thermostat rating will require acontactor(s). Contactors are ordered sepa-rately and mounted remote to the heater.Consult the Controls Section for details.

Electronic Process Control Thermocouples— Thermal sensors can be mounted in a teeon the heater outlet nozzle. Electroniccontroller is remote mounted. Option alsoavailable with process controller mounted onthe heater insulation jacket.

Ordering Information — To order circulationheaters with electronic controls, specifymodel, volts, kW and provide the followinginformation.

Overtemperature thermocouple: Yes No

High temperature limit controller: Yes No

Controller Model No.

Mounting: Integral Remote

Process control thermocouple: Yes No

Type:

Location:

Process controller: Yes No

Controller Model No.

Mounting: Integral Remote

Electronic Control Check List

Assembly Stock Delivery — Where heatersare listed as Stock (S) or Assembly Stock (AS),electronic control options are available asassembly stock delivery. When heaters arelisted with a standard mechanical Type ARthermostat, the thermostat will be provided onthe heater unless otherwise stated.

Note — Circulation heaters with a screw plugheader - Series NWHSSMT, NWHMT,NWHMTO and GCHMT are not available asassembly stock with a thermocouple welded tothe element sheath.

Outlet

High LimitController

Sensor

Stn. Stl. Sheath

1/8" Dia.

Expansion Loop

Element

Optional Controller Location

Tee

Outlet

T/C

2

Remote Mounted Electronic Control

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