Temperature telemetry systems let you measure the temperature of just about anything, when you either can’t be there or don’t want to be... or perhaps you just want to measure the temperature of something that moves!
Temperature telemetry means measuring temperature at a distance. But in a wider definition we often consider it to be two-way data communications where, in addition to temperature measurement data, there is often an exchange of operational information and control commands.
For example, if something gets too hot, assuming it's something we can control, we can remotely command it to turn off or cool down.
Telemetry brings temperature information back to you,
to wherever and whenever you want it. Want to measure the temperature
of something in the next room, in the next building, across town, in
another country… or even on Mars?
Wireless Telemetry is the answer.
No need to wait. Receive your temperature measurement information in near real-time.
Whether it’s a rotary kiln, the brakes or the engine of a racing car, or the muscle temperature of a swimming seal.
And if it moves, you need a wireless connection. The information is usually carried by radio – that is, electromagnetic radiation in the radio part of the electromagnetic spectrum. This is sometimes just called RF (Radio Frequency).
Temperature affects our lives so much that it’s important to be able to measure it. If you measure it, you can control and manage it.
With temperature telemetry you don’t have to go and get the data... it comes to you!
This reduces travel costs and greenhouse gas emissions if you don’t need to use a vehicle to collect it. It may even allow you to measure things you wanted to before, but couldn’t, because it was too expensive.
Assure yourself that the data is of good quality. You don’t want to find, at your next monthly data download, that nothing was recorded. It’s reassuring to see good data coming in, in real time, especially when it’s coming from somewhere far away.
When you want to know the temperature of blizzards or blast furnaces, you really don’t want, or need to be there carrying out the measurements yourself. A temperature telemetry system will let you stay at a safe distance.
When you free yourself from the constraint of wires, the applications are only limited by your imagination…
Here are the benefits. Wireless temperature telemetry can…
And yes, there are some disadvantages with wireless temperature telemetry...
... however, the advantages easily outweigh the disadvantages and these can usually be minimized or overcome.
Here’s the big picture...
Temperature telemetry lets you wirelessly monitor the temperature of many things continuously, 24/7, freeing up hospital staff for more productive tasks.
Set alarm thresholds so that relevant response personnel can be deployed in an emergency.
Staff can also be alerted to non-urgent tasks automatically. This can help bring certainty and order to a potentially chaotic situation.
Here are some practical temperature monitoring applications…
Temperature telemetry lets you monitor items such as food or medicines. Many chemical reactions double in speed for a 10 degree C rise in temperature. Temperature affects the storage time of perishable goods such as food and medicines.
If you don’t know the temperature history of these items, you can’t have confidence in their quality and may have to dispose of them simply because you can’t guarantee that quality.
You can track this in real time, locally or even from country to country, allowing food, medicines and other perishable products to be moved internationally - with confidence that their quality is being maintained – or know when it hasn’t been!
It’s essential not to "break the cold chain" when food, especially meat, poultry and egg products are being produced, processed, transported and distributed.
Keeping food products at a low temperature is the best way to prevent the growth of bacteria that could lead to food poisoning. Wireless temperature telemetry makes this practical.
Body temperature is vitally important to all animals, so the more we can learn about their dependence on it, the easier it is to understand their behaviour and how to manage them.
Here are some things you can do with animal temperature telemetry…
A temperature telemetry system starts with a temperature sensor...
Decide what type of sensor is best for your measurement
Most temperature sensors are designed to be in close contact (thermally coupled) to the thing they’re measuring.
These are good for measuring the temperature of specific objects, such as a pump or motor, or the air temperature in specific locations such as a factory or laboratory.
If you want to measure environmental temperatures, say between –20C and +50C, then an electronic linear sensor is a good choice.
However, if you want to measure higher temperatures, say up to 500C, then a thermocouple is a better choice. Unlike an electronic sensor, it will work happily at higher temperatures.
But there is a downside to using thermocouples...
Thermocouples aren’t linear (output doesn’t follow temperature directly). However, some temperature telemetry modules are specially made to use thermocouples and these convert the non-linear output to a linear one.
Some sensors, such as Infra-Red thermal imaging types, are non-contact, and can give a good big-picture view of temperature variations over a wider area such as a room or a building.
Other types of IR sensor can be used for non-contact monitoring of point sources of heat. Both types sense the electromagnetic radiation emitted from the heat source – in the IR part of the electromagnetic spectrum.
Consider what you need now... but also consider your future needs. If you make the right choice now you may not have to purchase another bigger system later.
Initially you may only want to measure one temperature point at one location but want to add more points later, as the size of your operation (or budget) increases.
Or you may want to measure several temperature points at each of a number of different places.
A good temperature telemetry system should be scalable (up and down) and easy to reconfigure when you want to add new temperature measurement points, or remove them.
There are many types of temperature sensor available and one size does not fit all.
You’ll need sensors that are suitable for the range of temperatures that you want to measure, otherwise…
When carrying out temperature telemetry you should ideally select a temperature sensor range that’s slightly wider than the range of temperatures you want to measure.
Say you want to measure temperatures between zero and 20 degrees. Select a sensor with a range as close as possible to this, but a little wider, say 0 – 25 degrees, depending on what’s available. Don’t select a sensor with a range of –50 to +150 degrees as you’d only use 10% (20 degrees out of 200) of the available range and the temperature changes would be under-represented.
With a temperature telemetry system, or any air temperature measurement, you need to mount the sensor...
Say you want to measure outside air temperature.
All you want to measure is the temperature of the air! It’s obvious, but sometimes people think they are measuring air temperature but may be also measuring the heat contributed by the sun’s direct radiation… or measuring heat re-radiated from the wall that the sensor’s mounted on, after the sun’s gone down.
This is one reason why there’s so much variation in (unofficial) reported temperatures.
When you measure air temperature you need to screen the sensor from any direct radiation from the sun, or re-radiation from nearby objects, especially concrete, brick or stone walls that can absorb and store solar energy during the day and re-radiate it at night – sometimes for hours!
It’s the temperature difference that drives heat flow. Put two things at the same temperature together and what happens?
Nothing. No heat flows from one to the other because there’s no temperature difference to drive it.
But if one of those things is a degree hotter than the other, heat will flow… from the hotter one to the colder one, until they are at the same temperature. Then there’s nothing left to drive the heat flow, so the flow stops... equilibrium!
On a good temperature telemetry system, the air temperature sensor will come with a screen to reflect the sun’s rays away from the sensor, so that direct radiation can’t significantly raise the temperature of the sensor.
You want the sensor to respond to ambient air temperature so the only thing around it should be air! The sensor should be out in the open and air should be allowed to flow freely over it. If the sensor is in an enclosure, this needs to be vented to allow airflow.
And if air circulation is poor...
Mount the sensor in an enclosure with a fan, to draw the air over the sensor. This is sometimes called an aspirated system. And because a fan may get warm during use, it’s important that it draws the air in and doesn’t blow fan-heated air over the sensor or the temperature may appear to be higher than it really is (in error).
For an aspirated wireless temperature telemetry system, you may want to use a solar panel and battery to power a small fan.
If your temperature telemetry system won’t be monitoring a critical process then you probably won’t want to do anything. However if you happen to be monitoring the core reactor temperature of a nuclear power plant!! then you’d want to generate alarms and initiate an automatic shutdown.
But there are lots of options between these extremes. Here are some for alerts and alarms that can be sent automatically...
Decide what’s appropriate for you and check that the temperature telemetry system has what you want before you buy it.
If raw temperature data consisting of rows of numbers doesn’t do it for you...
there are alternatives. Look for a temperature telemetry system that delivers an intuitive colorful graphic display right to your PC screen.
Choose a system with a good software
package that processes the raw temperature data right on your PC and
presents it as a graph or bar chart, showing minimum, maximum, average,
trends and other statistics, and maybe even generates a
professional-looking report that can be pulled out of the printer...
...and handed straight to the boss! And if you can customize your reports, better still.
Read more about wireless telemetry systems.