Silicone rubber heaters

Silicone rubber heaters derive their adaptability from their thin profile, low weight and capacity to fit in small spaces. While these flexible workhorses are durable, stable and capable of outlasting many of the component parts that surround them, they also require delicate care during installation to prevent damage and avoid premature failure. Bernardo Molina runs through the key considerations that must be made when applying silicone rubber heaters

Silicone rubber heaters boast a rapid warmup and efficient heat transfer, capable of operating at temperatures up to 260˚C, which provide consistent temperature uniformity while decreasing wattage requirements. They boast a wide range of industrial applications, used to protect liquid and viscous materials from cold temperatures, prevent condensation and prevent corrosion. 

Thanks to their pliant nature, silicone rubber heaters are conducive to fitting in tiny notches or isolated nooks. While this is a major advantage, this size and placement necessitate caution.

Safety considerations

When installing silicone rubber heaters, it is imperative to follow the instructions carefully to preserve the heaters’ structure and longevity. Though silicone heaters are pliant, they are prone to harm from over-flexing, pulling and cutting, which are the biggest causes of damage-related, pre-installation returns.

In this instance, it’s important to understand safety concerns to make handling as efficient as possible. After verifying the circuit integrity, installers should ensure the corresponding metal part for the heater is clean and smooth — metallic ‘burrs’ could penetrate the heater surface and cause a malfunction.

A critical step before heater placement is to remove any labels from the part. Failure to remove labels can create heat-related problems that impair heater function and even cause a fire hazard.

If a label is not rated for a heater’s operating temperature, the label becomes a fuel source. Certain types of labels can cause a chemical reaction that releases chlorides and breaks down the silicone rubber. Over time, this can lead to arcing or combustion.

Prior to installation, the heater should also be inspected for any damage, particularly on the ends and the interior surface that will contact the part. Never install a damaged heater.

Damage prevention

Silicone rubber heaters most often sustain damage during the installation process or when they are removed for maintenance on surrounding modules. Damage typically occurs when the heater is bent, pulled, twisted or trimmed.

These heaters are designed to fit tightly for optimal heat transfer, but should also fit without cutting and with minimal insulation compression and limited strain on the fasteners. 

Watlow, which manufacturers silicone rubber heaters, recommends a second fitting after the initial installation to ensure uniform contact to the part. It may be necessary to adjust the heater fasteners, but a thorough fit is important to prevent hot or cold spots, maintain steady heat transfer and prevent premature heater failure.

As an integral part of the machines that make semiconductors, silicone rubber heaters often operate in cleanroom environments where operating temperatures are stable and dust is negligible. Medical, food processing and aerospace applications often have similar requirements, but to a lesser degree, making silicone rubber heaters ideal for multiple industries and applications.

Although silicone rubber is water-resistant, the heaters should not be sprayed with or immersed in liquid and should remain dry to protect their long-term functionality.

Heater maintenance

Even with a life expectancy that can exceed ten years, silicone rubber heaters do not have a periodic maintenance schedule. However, there may be occasional maintenance issues that arise with the equipment in which the heaters are installed and may require the removal and reinstallation of the heaters.

Before removing the heaters from parts, allow them to cool completely as silicone rubber heaters are particularly vulnerable to damage from rough handling when hot. The removal should not require tugging or extreme bending.

It’s important to remain attentive of the bracket points and edges when removing the heaters as there may be additional fasteners or other protrusions that could harm the heaters.

Prior to reinstallation, silicone rubber heaters should be assessed for discolouration or brittleness, which are indicators of over-temperature exposure, as well as tiny punctures or other signs of damage that may have been caused by handling or contact with interference points within the equipment where the heater resides.

Silicone rubber heaters are flexible in more ways than one, from the applications they can be used in, to the pliable nature of them. However, while these heaters are durable and offer superior heat transfer, they must be handled carefully to prevent damage and equipment malfunctions.

Bernardo Molina is silicone rubber heater product manager at industrial electric heater manufacturer Watlow.