The more you know about temperature sensors the more likely you are to choose the right one, and to ensure its accuracy. Here are three common types of temperature sensors that you may want to consider:

• Thermocouples. These are generally the most common type of temperature sensor used. It is easy to use, affordable, and durable. Thermocouples are often used in places that will be permanent, because they may be destroyed if they are used moved. Because of their design and usage they are not usually considered to be the most accurate types of temperature sensors available.
• Platinum RTDs. The Resistance Temperature Detectors (RTDs), provide more accurate and reliable results. They are fragile and provide a higher e.m.f. output.  They are usually inexpensive and easy to use. It is important that the platinum RTDs are calibrated to continue providing accurate temperature readings.
• Thermistors. While these temperature sensors are not as rugged as some of the others, they can be used in industrial settings and beyond. Thermistors are considered to be highly accurate for both freezing and boiling temperatures, are small in size, and are also inexpensive.

When it comes to determining which type of temperature sensor is ideal for meeting your needs get professional advice if you are not sure. Being able to let them know what your temperature sensor needs are they can help you choose the best option. Speaking with a temperature sensor professional will also provide you with information about calibration and servicing that they may need in order to keep the one you choose working accurately.

However, with radio frequency (RF) technology having become more evolved and sophisticated in recent years, in many situations temperature monitoring is capable of being performed wirelessly. For example, wireless temperature sensors are now being used to monitor cold storage containers in laboratories and hospitals where materials such as blood and tissue samples, organs for transplant and pharmaceuticals must be kept within a very specific temperature range.

Advantages of Remote Temperature Monitoring

Wired temperature measuring instruments that not only take up space within a storage container or refrigeration unit but must also be manually monitored are slowly being replaced by more compact, less cumbersome systems. Wireless, RF-equipped thermistor sensors can be strategically placed within a storage unit, which will facilitate the continuous measurement of interior temperatures and relay that information to monitoring devices in real time. Even if a storage unit is mobile, temperature information can still be monitored, and that unit’s movements tracked.

Wireless systems such as these eliminate the need for cabling to be strung through refrigeration unit doors, where even the slightest gap in a door seal may compromise or decrease the effectiveness of an interior cold storage environment. Wired temperature monitoring systems also limit the range of recording device and monitoring station placement—among other peripheral equipment—which generally cannot be situated too far from where temperature sensors are located.

In addition to giving monitoring personnel the ability to access vital temperature information remotely, if a storage unit or container fails, becomes unplugged or for any reason falls out of a prescribed temperature range, alerts can be set up to be sent to just about any type of mobile device, including phones. The methods that we use to measure temperature and transmit data are changing for the better. Not only have wireless technologies added flexibility to these endeavors and made them much more efficient, but especially in the medical and pharmaceutical industries, they are enhancing our ability to preserve life and limb.

Temperature measuring and monitoring on an industrial level is of course a much “different animal” than that which we are aware of in domestic circles, and in our everyday lives. Although the thermocouple temperature sensors in our home ovens, for instance, are accustomed to measuring temperatures in the 400 to 500 degree range, this is nothing compared to the excessively harsh environments to which higher grades of these sensor types are exposed on a daily basis. Temperatures exceeding 2000 degrees Celsius are not uncommon in many of these settings.

The Critical Role of Temperature Calibrators

Depending on the application, even the slightest deviation from a mean temperature value on a sensor can lead to serious issues from either a safety or a productivity perspective, or both. Therefore, temperature monitoring equipment must be under constant scrutiny, and temperature sensors themselves must be continuously calibrated.

Very basically, when it comes to industrial temperature sensors, calibration consists of establishing a fixed point, or “reference point,” and taking multiple considerations into account in order to verify the accuracy of a sensor. Some of these considerations include noise levels, “drift” potential, sensor type and tolerance and how the sensor is affected by the surrounding environment, and by the devices to which it is attached.

There are a variety of techniques and systems used to ensure that temperature sensors are properly calibrated. In many situations, a “dry block calibrator” may be used to ensure sensor temperature uniformity, and the “liquid bath” is also a very popular method for calibrating sensors. Some sensors can also be connected to devices that will automate the calibration process. But regardless of the approach to calibrating an industrial temperature sensor, a high degree of vigilance and consistency must be employed in this area. Especially in potentially volatile situations, any neglect in the careful monitoring of temperature measuring equipment can end up being very costly on a number of levels.

A Thermistor vs. Thermocouple Comparison

Thermocouples are the most popular and widely-used temperature sensors in the world. They are common in industrial and scientific circles, and come in a number of “types,” consisting of a variety of different metals and configurations.

Thermocouples are built to suit applications ranging from sub-zero to extremely high temperatures. In fact, one of the major advantages of the thermocouple is its ability to measure higher temperatures than any other sensor. Higher-end thermocouples are designed to measure temperatures well over 2,000 degrees Celsius.

Thermistors are “resistance” temperature measuring devices that conduct electricity in proportion to changes in temperature. In this sense, they are “self-regulating,” used in applications requiring operation in very specific temperature ranges.

Thermistors are used in power supplies, heaters, freezers, circuit breakers and numerous industrial settings. Although they are unable to measure temperatures at the range of a thermocouple, thermistors are much more accurate and stable than their counterpart.

Additionally, a more complex process is often required in the setup of a thermocouple. The actual operation of a thermocouple is not linear with temperature due to the fact that a signal must travel over a certain distance as it is processed, increasing the possibility for errors and inaccuracies.

Thermocouples are durable; generally less expensive than thermistors; and able to perform in situations that thermistors cannot. However, in the appropriate setting, thermistors offer a level of precision and sensitivity that the thermocouple is unable to attain.

These temperature measuring instruments are commonly referred to as “smart sensors” for their ability to gather and digitally transfer temperature-related information to some form of monitoring device or station. Each of these sensors has its share of advantages and disadvantages. Each is very efficient when used in applications for which it is well suited. But other than under circumstances in which extremely high temperatures are in play, the RTD is considered to be the most stable and accurate of the three.

RTDetails

RTDs come in various styles and configurations, including 2-wire, 3-wire and 4-wire versions. There are many variables in regard to levels of accuracy within the different types of RTDs. But generally, the more wires, the greater the accuracy of the RTD.

A basic RTD consists of a thin wire coiled around a non-conductive base often composed of ceramics. It contains a resistance element made from materials such as platinum, nickel or copper. This element measures the temperature of a source and weighs it against a known resistance value.

Unlike other self-acting sensors, RTDs must be connected to a power source to function. The resulting low-level current enables the voltage to be properly processed and the resistance to be calculated. The resistance element will adapt to whatever temperature changes occur.

Depending on the temperature measuring and monitoring requirements of a particular application, higher-end RTDs are capable of measuring temperatures as high as roughly 850 degrees Celsius or as low as -200 degrees Celsius. Although they may be more expensive than other smart sensors, RTDs are preferred over their counterparts in situations that necessitate extreme accuracy and consistency.

The very special sensors used for industrial-level temperature measuring and monitoring endeavors basically boil down to three main types: The thermocouple, thermistor and the resistance temperature detector (RTD). From situations that demand acute precision at relatively moderate temperatures to those calling for stability and accuracy under extreme temperatures, just about any temperature measuring requirement can be satisfied between these three sensor types.

Metals Make the Difference

Thermocouples, thermistors and RTDs all possess certain strengths and weaknesses, and one may be better suited for a particular application than the other. For instance, though RTDs and thermistors are generally known to be more sensitive and accurate than thermocouples, no other sensor can compete with the thermocouple when it comes to operating under conditions in which temperatures are excessively high.

However, one thing these three sensors do have in common is that they are at least partially constructed of various metals or metal alloys. Metals are highly reactive to temperature changes. In the case of resistance-based sensors such as RTDs and thermistors, these sensors operate on the very principle that the electrical resistance within metals will increase or decrease according to the temperatures to which they are exposed.

Thermocouples consist of two dissimilar metals that are joined at one end and generate a voltage when the joined end is exposed to heat or cold. This voltage is eventually converted into a temperature reading. Thermocouples are made up of metals and alloys such as nickel, iron, chromium, constantan and alumel. Thermistors contain conductive sintered oxides consisting of elements such as manganese, nickel and chromium. RTDs are constructed of metals that include nickel, copper and platinum, with platinum being by far the most preferred metal for this type of sensor.

The metals and alloys used in these devices vary according to the temperature range and accuracy requirements of a given application. But these materials are essential components within the temperature probes and sensors that are entrusted to effectively and efficiently perform industrial temperature monitoring functions, day-in and day-out.

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This blog is written and published by Instrulab Inc.

Thermocouples are sturdy, dependable, fast-responding and are quite cost-effective compared to many of other sensors. They consist of two dissimilar metals joined together at one end. The joined end is called the “hot junction” and the other end is called the “cold junction.” The temperature difference between the hot or “measuring” junction and the cold or “reference” junction creates an electric current from which application temperatures are determined and are subsequently sent to a temperature monitoring apparatus.

There are a fairly wide range of thermocouple types available to suit whatever a particular application may require. Some thermocouple types are even capable of measuring temperatures of up to roughly 3000 degrees Celsius. However, due to the non-linear nature of thermocouples and the way that they are configured, these sensors often require the assistance of peripheral devices to assure that they remain precise, consistent and properly calibrated.

Cold Junction Compensation

Temperature readings from thermocouples and other types of sensors must be transmitted to monitoring equipment via electronic signal. Therefore, devices that not only facilitate signal conversion — such as analog-to-digital converters (ADCs) — but also process and condition signals for maximum transmission strength and reporting accuracy are often attached to and work in conjunction with sensors.

In thermocouples, it is imperative the temperature of the reference junction be known in order to accurately calculate temperature differential. Maintaining a cold junction temperature of zero degrees is optimal, but is often quite difficult to achieve, especially in situations where a thermocouple is located in extreme temperature environments. In order to address this issue, a technique called “cold junction compensation” is used.

Cold junction compensation is a method by which another sensor such as a thermistor is connected to the thermocouple’s reference junction. Whenever the reference junction temperature strays from zero, a compensating voltage is administered to the thermocouple to correct the reference temperature and generate precise readings. In essence, cold junction compensation acts as a built-in calibrator to ensure optimal thermocouple performance, even under the most demanding conditions.

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This blog is written and published by Instrulab Inc.

There are a few types of temperature sensors built to handle the rigors of temperature measuring and monitoring on an industrial scale. Two of these are the thermistor and the resistance temperature detector (RTD). Unlike their thermocouple counterpart, these two sensor types are not equipped to withstand environments inordinately harsh or where excessively high temperatures exist. But both have their share of distinct advantages.

The Thermistor versus the RTD

There are two types of thermistors: Positive temperature coefficient (PTC) and negative temperature coefficient (NTC). The electrical resistance within PTC thermistors increases along with increasing temperatures. The resistance within NTC thermistors decreases as temperatures increase.

Thermistors are very sensitive to temperature changes and stable and extremely accurate at limited temperature ranges. They are also relatively inexpensive compared to other sensor types.

RTDs are not quite as sensitive as thermistors. But they are generally the most reliable and accurate sensors available. Although they cannot compete with the thermocouple when it comes to measuring extremely high temperatures, the temperature range at which they are capable of functioning very effectively is still significant; between roughly -200 to 700 degrees Celsius.

Interested parties must be very discerning when it comes to selecting temperature probes and sensors for temperature-sensitive industrial equipment and processes. There are a wide variety of RTD and thermistor configurations to choose from, all possessing a diverse array of capabilities. Along with thermocouples, these two sensor types provide coverage for just about any industrial temperature monitoring endeavor.

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This blog is written and published by Instrulab Inc.

Recent generations of sensors are often referred to as “smart sensors” due to the functionality that has been added to them over time. The technology surrounding temperature sensors in particular has evolved at a steady pace and has greatly enhanced these devices in terms of efficiency, convenience and overall performance.

Improvements across the Board

Industrial temperature sensors such as the thermocouple, thermistor and the resistance temperature detector (RTD) are capable of processing temperature measurement data faster and with more precision than ever before. They can also transfer that information to various types of monitoring apparatuses in real-time. The latest signal conditioning and processing equipment not only adds strength to a signal being transmitted by one of these temperature sensors, but also increases its linearity, which results in improved accuracy.

Additionally, with the wireless, fiber optics, Internet and DSL systems available today, temperature data can be accessed anytime, anywhere from a variety of devices. Critical temperature-sensitive processes or applications can be remotely monitored from personal computers, laptops, tablets and even mobile phones. These devices can also be set up to receive warnings or alerts via instant messaging or text messages.

For situations in which temperature uniformity and stability are imperative, much work is being done to increase the reliability and effectiveness of temperature measuring and monitoring systems. But for now, where potentially volatile or even life-threatening circumstances could ensue if temperatures within a certain process or piece of equipment should stray out of a prescribed range, the aforementioned developments in smart sensor technology have been a tremendous boon.

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This blog is written and published by Instrulab Inc.

The Mission of the Wastewater Treatment Plant

Basically, wastewater treatment facilities use various methods to clean and purify wastewater. Sewage and water that has been used in industrial operations is filled with bacteria, chemicals, particulates, microorganisms and other contaminants that must be eradicated or reduced to acceptable levels before it is reusable or environmentally sound.

Ensuring a Smooth Operation

There are many aspects within the wastewater treatment process that requires measuring and monitoring, such as water levels, flows, pressures and pH levels. But pumps, boilers, processing areas and settling tanks must operate within very specific temperature ranges. Therefore, it is crucial that steadfast and reliable temperature measuring, monitoring and controlling apparatuses are in place.

In order to ensure accuracy and consistency in the monitoring of wastewater treatment plant temperatures, sensors such as the thermocouple and the thermistor are often used. Thermistors are extremely accurate at lower temperatures. Thermocouples are sturdy and dependable in harsher environments where temperatures reach levels that no other sensor could withstand.

Wastewater treatment facilities operate under strict regulatory guidelines, and for good reason. Sewage and contaminated water must go through a multi-stage progression before it is fit to be reintroduced into the environment. This process includes the trapping and straining of larger objects and particles, the separating of harmful bacteria and organic matter from the wastewater and ultimately the oxygenation, chemical treatment and purification of the wastewater. Tried and true procedures and controls, including sturdy and precise temperature sensors, make this process possible.

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This blog is written and published by Instrulab Inc.