Using Flexible Heaters in Food Service
arcstone
Restaurants, hotels, cafeterias, and businesses that serve food may keep it in display cases, cabinets, or rolling racks. These areas hold a specific temperature to keep meals warm. Keeping food at a safe temperature is one of the most critical factors. Letting food become cold can promote bacteria growth, which can cause sickness. There are other times when items must be at a specific temperature. For packaging, liquids must be at a specific temperature to prevent solidification.
Why are flexible heaters ideal for food service display casing?
Flexible heaters provide efficient heat transfer and even heat distribution. They contain conductive heat spreaders to ensure consistent temperatures across the product. The lightweight and bendable construction provides the ability to conform to any surface.
They’re also moisture-resistant, making them ideal for applications in the food industry. Electronics are sensitive to temperature and can suffer damage from exposure to moisture.
Outstanding thermal stability and durability mean there is less equipment downtime. Flexible heaters are cost-effective and last longer than traditional heaters. Flexible heaters are corrosion-resistant, which helps them withstand harsher applications. When bent, the conductor won’t crack or break, which is the leading cause of heater failures. Their small, lightweight design adds to the versatility. Because of their flexibility, they conform to the shape of most surfaces.
Consistent heat transfer
Some products must be kept at a steady temperature for the food industry. This can be a challenge. A small heating source can focus too much heat in a specific spot or not enough. Flexible heaters are small and thin. But they can still provide enough localized heat to maintain a constant temperature.
Flexible heaters offer consistent thermal transfer since they consist of etched foil elements. They also allow the user to differentiate heat along the application. Consistent thermal transfer ensures that the heater provides the right amount of heat. The heater can offer consistent heat distribution along curved or custom surfaces. It can be placed on drums with liquid food products, bins, and rolling racks.
Low outgassing
The materials in flexible heaters have low outgassing from heat and extended use. So, there will be no released gasses that may infiltrate the cabinet and impact the taste and quality.
Viscosity control
Food that travels through a processor, such as sauces, must stay at a certain viscosity to travel through pipes and dispensers. If the food cools, it may become too solid to flow, gumming up packaging systems. Kapton flexible heaters maintain the viscosity of the food for processing.
Maintains food quality
Temperature changes can affect food quality and texture. Fast food and banquet food may sit out for lengths of time before serving. The food must stay warm until the customer consumes it. This food can enter a “danger zone” between 41°F and 135°F. The FDA states that food should never be within this range for more than four hours. Flexible heaters may be placed into food trays or warming cabinets to maintain temperatures above this range.
What heater is best suited for food service display?
Flexible heaters are made from silicone rubber, polyimide, or polyester film. Thin layers cover wire-wound or etched foil circuits to allow for rapid heat transfer.
Silicone rubber heaters
Custom silicone rubber heaters provide flexibility and performance.
Silicone rubber heating elements are versatile, lightweight, and efficient. The thin, flexible design allows rapid heat transfer and high dielectric strength.
Silicone rubber heaters can include a variety of temperature controls, including thermostats, sensors, and thermal fuses.
Thermostats provide safety and control. The thermostat can be placed over a heated section to prevent overheating so the heater doesn’t exceed a certain temperature. Engineers can also mount the thermostat to expose the sensing side to open air. This is best when the heater is used for condensation or freeze prevention.
Silicone heaters can also include temperature sensors. They may be mounted over a non-heated or heated section to control the heater’s temperature.
Thermal fuses are single-use devices. They act as a fail-safe device to shut down the heater during a control failure. As with the other devices, they can be placed over a non-heated or heated section.
Wire-wound heaters
Flexible silicone heaters use wire-wound elements laminated between silicone to ensure a uniform heat profile. This is best for large heating elements, low-watt densities, and small production runs. Wire-wound design is a solution to the limitations of etched foil technology. It’s easier to conform to the size and shape of the application or to concentrate the heat in a specific section.
Etched foil heaters
Etched foil heaters are superior for high watt density and higher temperature operation. They provide twice the output wattage of wire wound technology. Flexible heaters use etched circuits laminated between silicone to provide quick heat transfer. Etched foil circuits need wider widths to accomplish the same wire resistance. But, the process enables spacing between elements to be as tight as 0.004”.
Etched foil is made from aluminum, steel, chrome, copper, and constantan alloys. Silicone etched foil has internal element coverage of more than 50% of the heating area. This coverage lowers the internal heating element temperature, providing a longer heater life.
Polyimide heaters
Polyimide, or Kapton, flexible heaters provide temperature control for food industry applications. They’re used in food trays, heating and display cabinets, and other devices.
Polyimide heaters are the solution to heating curved and irregular surfaces. They’re constructed of a thin, etched-foil circuit laminated between two polyimide films. The design offers dimensional stability, dielectric strength, chemical resistance, and low outgassing. This increases flexibility while allowing proper thermal transfer between the heater and the surface.
Low outgassing means that the release of gas in the material is minimal. Outgassing can cause contamination if it condenses onto sensors in a closed environment.
Kapton heaters offer a quicker thermal transfer and lower temperature threshold than silicone. The ultra-thin, lightweight profile promotes efficient heat transfer and uniform distribution.
Polyimide heaters are both abrasion and acid-resistant. Because we can create designs of any shape, they are cost-effective and energy-efficient.
Why Hi-Heat?
Our customer had issues with their heater supplier’s ability to bond to stainless. We worked with their engineering team for weeks and provided samples. We provided a solution that guaranteed the heater would remain affixed to the component. Over the last 25 years, we have supplied them with thousands of heaters. To this day, we remain a top-tier supplier.
