Hazardous Location (Hazloc) heaters provide a safe, reliable source of warmth in areas where volatile or flammable materials are present. They should not be confused with the brand Hazloc HeatersTM although the term hazloc can be used interchangeably.
From oil and gas operations to chemical storage, hazardous location heaters require a unique design to provide heat safely without an open flame or spark. This article provides an overview of explosion-proof heaters, their benefits, and what to look for when purchasing.
What are Hazardous Location Heaters?
Hazloc heaters, also called explosion-proof heaters, are electrically powered heaters that are intrinsically safe for hazardous or explosive environments. The difference is a typical electrical switch or motor creates sparks with enough heat to cause an explosion in a hazardous environment. An explosion-proof heater means the electrical current flow is limited or insulated to prevent sparks in a potentially combustible atmosphere.
Hazardous location heaters are modified to eliminate sparks or other sources of ignition.
How Do Hazloc Heaters Transfer Heat?
Explosion-proof heaters use a double-wall enclosure that creates a thermal break between the heat source and the external environment, preventing the heat source from reaching dangerous levels.
They transfer heat by convection or conduction. Convection heaters use fans to force air across the heating medium, such as tubing filled with a heated liquid. Conduction heaters such as tote and drum heaters contact the surface, transferring heat directly from the heating source to the wall of the drum or tank.
In both cases, the electrical components require heavy insulation to prevent a spark or the heating element from contacting the atmosphere or container. The heaters incorporate an automatic safety shut-off if the unit gets too hot.
Are Convection Heaters Energy Efficient?
Forced air convection heaters are energy efficient because they circulate hot air throughout space with an efficiency of 80% to 90%. Hazloc heaters offer Hazardous location freeze protection with high energy efficiency and safety.
Are Convection Panel Heaters Good?
Convection panel heaters are less expensive to run than electric radiators or forced fan-type heaters. They heat the air, which rises and pushes the cold air down, creating circulation. They are best for small areas like dressing rooms or offices.
Features and Benefits of Hazloc Heaters
Safe and reliable – Hazloc heaters can withstand hazardous environments and control temperatures.
Simple to install and operate – Most Hazloc heaters can be easily plugged into the system, allowing for easy installation and operation. They use a thermostat and work like any other heater.
Customizable to any application – Hazloc heaters come in various wattages and configurations to suit specific applications.
Energy efficient – Hazloc heaters operate at high efficiencies and run cooler than other heating systems.
Easy to maintain – Hazloc heaters have simple designs and can be easily maintained and repaired when necessary.
Types of Hazloc Heaters
For freeze protection and or to maintain a constant temperature, there are four primary hazloc heater types:
#1. IBC Tote and Drum Heaters
Hazardous area drum and tote heaters supply heat directly to containers by wrapping around them like a blanket. Some types use adhesive to permanently bond the heating element to the surface of the drum or tote. A better solution is a portable blanket or wrap that secures around the surface using straps allowing it to transfer to another container as needed.
#2. Gas Cylinders and Propane Tanks
Hazardous location freeze protection includes gas cylinders and propane tanks stored in areas prone to freezing conditions. Gas tanks can leak, creating a dangerous situation. Tank heating blankets are intrinsically safe, with built-in thermostats preventing sparks or overheating.
#3. Forced Air and Radiant Heaters
Liquid-to-air heat exchangers are the safest to heat large open areas that may pose a fire or explosion threat. There is no exposed electrical or gas flame heating element. The fan motor and the thermostat are enclosed to avoid contact with the ambient air.
#4. Trace Heating
Trace heaters are insulated wires that wrap around long lengths of pipes, valves, and other related equipment. The resistive element between two parallel copper conductors limits the heat of the trace heater corresponding to the ambient temperature.
Three brands that manufacture process heating for hazardous locations are Powerblanket, Hazloc, and Exheat. Powerblanket specializes in heat tracing, drums, and tote heaters. EX Heater manufactures portable explosion-proof electric heaters, and Hazloc Heaters™ specializes in permanent explosion-proof electric unit air heaters for hazardous locations.
Hazloc Heater Safety Considerations
When choosing a hazloc heater, it’s important to consider the hazards present in the system, such as dust or fumes, and their potential to cause a fire or explosion. Locations such as coal preparation areas, grain elevators, oil and gas drilling rigs, paint and chemical storage, or any place where flammable products exist require custom hazardous location solutions.
In the U.S., Article 500 of the National Electrical Code specifies the kinds of hazards using a Class/Division/Group system to identify threats in the atmosphere in the area.
- Classes – describes the general nature of the hazardous material
- Divisions – identifies the probability of hazardous material being present
- Groups – specifies the type of hazardous material
You can see specific examples in this chart.
Various system configurations are available for hazloc heaters, including full and partial flow. For more details, get the hazardous location unit heater spec sheet from Powerblanket.
When purchasing a hazloc heater, look for cCSAus Certified or cULus Listed. Underwriters Laboratories (UL) and CSA Group (CSA) are Nationally Recognized Testing Laboratories (NRTL). They test the quality of electrical components in their respective countries. Products must meet the U.S. standards of the National Electrical Code (NEC) or Canadian certification standards of the Canadian Electrical Code (CEC) before being installed in a hazardous location.
To find the best intrinsically safe heater for your operation, contact Powerblanket.