Heat cards are a portable, wearable and inexpensive method of temperature tracking, making them a vital part of every heat safety program. Keeping your workers safe demands constant vigilance, as weather and worker conditions can change rapidly. The surest way of instilling this vigilance is giving everyone a tool they can use to monitor temperature. That includes safety personnel, supervisors and every worker who will be in the heat.

Temperature-monitoring heat cards are embedded with liquid crystals that respond as the temperature changes. It’s a solution that fits perfectly on any worksite, and heat cards can be customized with company branding and essential reference information.

How heat cards work

Heat cards are designed with temperature-sensitive areas that change color as the temperature changes. This is made possible with the use of thermochromic liquid crystals, or LCs. LCs are used in many applications and can be found in laptops and watches, though the LCs used in these applications are sensitive to voltage. The LCs used on heat cards are instead sensitive to temperature. When exposed to heat, LCs change their position slightly, which causes the LC matrix to absorb different wavelengths of light. To the human eye, this registers as a change in color.

The typical heat card comes with an embedded label that includes LCs. The label acts like a temperature spectrum, so as the temperature changes, different parts of the label change color. This makes it easy for people to read the temperature immediately, which may be critical in an emergency situation.

How accurate are heat cards?

In almost all typical work conditions, LCs are accurate within a degree of the actual temperature. When the temperature is below -22 degrees Fahrenheit or above 138 degrees Fahrenheit, LCs are accurate within two degrees.

Heat cards with embedded LC thermometers are designed for readability and can monitor temperatures in nearly any range, so they can be customized for particular applications. For example, heat cards given to construction workers might monitor temperatures between 90 and 104 degrees Fahrenheit.

LCs are flexible in their ability to monitor temperature, as they can detect a huge range of temperature values and can be customized to any range. They can also be customized for 2 or 5 degree increments, depending on what the client prefers. Finally, heat cards can display Celsius instead of Fahrenheit, should the client prefer that as well.

Why heat cards work

No other temperature-monitoring technology is as convenient as heat cards. They are lightweight and the card can be worn without causing an issue. The cards are easy to read and can be done so within seconds, so if there’s a sudden surge of heat, workers know exactly what they are contending with.

Heat cards can be used over and over, and without the need for power. That means no batteries, no recharging and no maintenance. LCs are accurate within a degree, which makes them a reliable option for monitoring temperatures and keeping workers safe.

Companies can also customize their heat cards to provide valuable reference information or instructions should there be an emergency. Reference information can include emergency contacts or procedures, information on hydration or rest breaks, or even a small map to show workers where to go when taking a break or when exhibiting signs of heat-related illness.

Why every worker should have a heat card

As workers are usually the first to experience the rigors of intense ambient heat, it makes sense that they should have the ability to monitor it. Once workers are accustomed to their heat cards, they can be checked in just a few seconds and anywhere the worker is. There’s no need to stop everything just to check the temperature.

Because workers are at the highest risk of coming down with heat-related illness, supervisors will often pair them together and make each accountable for the other’s safety. This can be a life-saving approach to employee safety, but it also requires workers to make judgment calls about when to seek help for their coworkers. Heat cards give workers more information to consider and can alert people when working conditions have become dangerous. The more people with heat cards, the more likely it is that workers will stay safe on the job.

It’s not easy for health and safety personnel to keep a close eye on every worker. When workers are high off the ground or underground, there may be no way for safety personnel to check them. Heat cards are a valuable resource to these workers, who may only have themselves or a coworker to rely on for safety. Heat cards are the canary in the coal mine in this context, alerting workers to dangerous conditions before anything or anyone else can.

Finally, heat cards remind workers of what symptoms or risks to pay attention to when assessing their own condition, or the condition of coworkers. Keeping this reference on hand ensures immediate action can be taken in case of an emergency.

Information is one of the best defenses against heat-related illness, including information about working conditions, what to do in the event of an emergency, and when an emergency is likely to occur. Heat cards provide this information in a format that is easy to carry, reference and use, keeping workers safe on the job.