| | | All industrial heating elements inherently pose burn, fire and electrical shock hazards. These can result in injury to personnel, or damage to plant and process. The user is responsible for determining heater-to-application suitability. Care should always be exercised in heater selection, installation and use. Each shipment comes with Installation and Maintenance Instructions. This document is specific to the heating element or assembly. Take time to review and understand the Installation and Maintenance Instructions. This useful information will maximize safety, heater performance, efficiency and life. All Watlow heaters should be installed by qualified personnel in accordance with the National Electrical Code and any applicable state or local codes. The following recommendations apply to all Watlow heating elements and assemblies: | | • Carefully read, understand and follow the Installation and Maintenance Instructions. • Always disconnect electrical power prior to installing, servicing or replacing electric heating elements and/or assemblies. • All heaters should be used with appropriate and approved temperature sensor/control device(s). • Do not use industrial thermostats for high-limit sheath protection. Thermostats fail in a closed circuit mode and will not cut power to the heaters. Limit control should be provided by an isolated, redundant sensor and control system of the appropriate type, design and installation. • Electrical termination enclosures should be selected to match the application's environment and be able to withstand worse-case failures especially in hazardous locations. | | • Avoid fire hazards. Electric heaters can develop temperatures that produce an auto-ignition© source. Avoid mounting heaters in atmospheres containing combustible gases, vapor or dust. Article 501 of the National Electrical Code (NEC) requires that maximum sheath temperature, when the heater is continuously energized, not exceed 80 percent of the surrounding atmosphere's auto-ignition temperature. • Avoid contact with, and keep heaters far enough away from, combustible materials. • Element watt density should not exceed the recommended upper limit for the substance being heated. • Elements used in clamp-on applications should have sufficient contact with clean metal surfaces for efficient thermal conductance. | | |
| | | ©Auto-ignition is the minimum temperature required for a flammable substance to ignite or cause self-sustained combustion independently of the heating element (see National Fire Prevention Agency (NFPA) 325M, Fire Hazard Properties of Flammable Liquids, Gases and Volatile Solids). | | |