Heater Catalog - Watlow

Circulation HeatersWATROD and FIREBARCirculation HeatersTechnical DataMaximum VelocitiesThe rate at which a gas or liquid flows through inlet andoutlet pipes is critical to maintaining the desired outputtemperature. Pressure drop through the circulation heatermust be considered to properly size blowers or pumps.The Maximum Velocity to Avoid Excessive Pressure Dropchart gives recommended maximum velocities, in feet persecond and meters per second of gas or liquid beingheated and nominal pipe size.Maximum Velocity to Avoid Excessive Pressure DropNominal Pipe Size Maximum VelocityFluid in. ft/sec (m/sec)Gases All 200 (61.0)Liquid 4 and smaller 10 (3.0)Liquid 6-8 15 (5.0)Liquid 10-12 19 (6.0)Liquid 14-16 21 (6.4)Liquid 18-20 23 (7.0)Liquid 24 24 (7.3)Vessel Orientation GuidelinesCorrectly orienting the heating vessel assures lowerterminal enclosure temperatures and element immersion.Detailed instructions on vessel orientation are containedin the Installation and Maintenance Instructions thataccompanies all circulation heaters.The following are guidelines for vessel orientation in liquidand gas heating applications.LiquidsOrient circulation heater:• Horizontally with inlet and outlet pipes pointing up• Vertically with the terminal enclosure up and the inletpipe on the bottomThese orientations ensure the heating elements will beimmersed at all times and help prevent premature failure.Air or GasesOrient circulation heater:• Horizontally with the inlet nozzle closest to the terminalenclosure• Vertically with terminal enclosure at the bottom of thetank. Use the nozzle nearest the bottom as the inletconnectionIf installation constraints do not allow mounting inaccordance with these guidelines, contact yourWatlow representative.WATLOW ®Application Hints• Select the recommended heating element sheathmaterial and watt density for the substance beingheated. Use the Supplemental Applications Chart onpages 555 to 558. If unable to determine thecorrect heating element type and material, contactyour Watlow representative.• Assure selecting proper vessel by considering thepressure or flow rate, process temperature andcorrosiveness of the media being heated. If assistancewith vessel selection is required, contact your Watlowrepresentative.• For maintenance/replacement procedures, retain anarea twice the circulation heater’s overall length topermit easy removal and inspection of screw plugor flange heater assemblies.• Choose a FIREBAR assembly when you require:• A smaller package• More kilowatts or lower watt density in an equallysized WATROD circulation tank• Minimize problems associated with low flow or lowliquid level conditions with a low liquid level sensorand/or sheath high-limit control.• Ensure wiring integrity by making sure terminal enclosuretemperature does not exceed 400°F (205°C).• Size power feeder wires in accordance with nationalelectrical code guidelines and other applicable codes.• Protect against electrical shock by properly groundingthe unit per NEC requirements.• One or more circulation heaters may be connected inseries to achieve the desired total kilowatt ortemperature output.335