Technical Learning

The same year (1821) that Thomas Seebeck made his discovery about thermoelectricity (Seebeck effect, see thermocouples), Sir Humphrey Davy announced that the resistivity of metals showed a marked temperature dependence. Fifty years later, Sir William Siemens proffered the use of platinum as the element in a resistance thermometer. His choice proved most propitious, as platinum is used to this day as the primary element in all high-accuracy resistance thermometers, Pt100, Pt1000 etc.

In fact, the Platinum Resistance Temperature Detector, or RTD Pt100, is used today as an interpolation standard from the oxygen point (-182.96°C) to the antimony point (630.74°C)...

What is pH? pH, which is the measurement of hydrogen ion concentration, describes the degree of acidity or alkalinity of a solution. pH measurement as well as pH control is a critical factor in a wide range of industrial applications – including pharmaceutical manufacturing, food and beverage production, dairy and agriculture, water treatment applications, and countless others.

pH control is often vital in ensuring the quality of a product...

A thermal mass flow meter measures the flow rate of gas mass based on the convective heat transfer of a heated surface to the flowing fluid. The components of a basic thermal mass flow meter include two temperature sensors with an electric heater between them. The heater can protrude into the fluid stream or can be external to the pipe.

In the past, mass flow was often calculated from the outputs of a volumetric flow meter and a densitometer. Density was either directly measured, or was calculated using the outputs of process temperature and pressure transmitters...

A signal conditioner is a device that converts one type of electronic signal into a another type of signal. Its primary use is to convert a signal that may be difficult to read by conventional instrumentation into a more easily read format. In performing this conversion a number of functions may take place.

Signal conditioning is a vital process performed within the Data Acquisition System. It involves the manipulation of the analog signal output from the sensors to prepare it for the next stage of processing. Signal conditioning amplifies and converts the signals from the sensors or...

It is not practical to compare RTDs (Pt100 and others) and thermocouples generally. However, if we compare their performance in terms of specific criteria, we can see which is best suited for specific applications. Thermocouples are best for working at high temperatures. New manufacturing techniques have improved the measurement range of RTD probes, but more than 90% of RTDs are designed for temperatures below 400°C.

In contrast, some thermocouples can be used at up to 2500°C. Thermocouples are generally cheaper than RTDs...

An infrared thermometer is a sensor that consists of a lens to focus the infrared (IR) energy on to a detector, which converts the energy to an electrical signal that can be displayed in units of temperature after being compensated for ambient temperature variation. This configuration facilitates temperature measurement from a distance without contact with the object to be measured (non-contact temperature measurement).

As such, the infrared thermometer is useful for measuring temperature under circumstances where thermocouples or other probe type sensors cannot be used or do not produce accurate data for a variety of reasons...

A pressure transducer, often called a pressure transmitter, is a sensor that converts pressure into an analog electrical signal. Although there are various types of transducers, one of the most common is the strain-gage wheatstone bridge pressure transducer.

The conversion of pressure into an electrical signal is achieved by the physical deformation of strain gages which are bonded into the diaphragm of the pressure transducer and wired into a wheatstone bridge configuration. Pressure applied to the transducer produces a deflection of the diaphragm which introduces strain to the gages. The strain will produce an electrical resistance change proportional to the pressure...

The thermocouple wire or cable is used to manufacture thermocouple probes in order to sense temperature using the point of cold junction compensation (cjc end). On the other side, as it has been explain in this other article, a thermocouple is a sensor for measuring temperature, that consists of two dissimilar metals that are joined together at the sensing end.

Different thermocouple types (e.g. J or K type thermocouple wire) use different mixtures of metals in the cable. At the cjc end, the millivolt value provided by the thermocouple represents the difference in temperature of the sensing end as compared to the cjc end (also called the reference end)...

Temperature can be measured via a diverse array of sensors. All of them infer temperature by sensing some change in a physical characteristic. Six types with which the engineer is likely to come into contact are: thermocouples, resistive temperature devices (RTDs Pt100 and thermistors), infrared radiators, bimetallic devices, liquid expansion devices, and change-of-state devices.

Choose the right temperature measurement instrument for your application...

A load cell (or loadcell) is a transducer which converts force into a measurable electrical output. Although there are many varieties of force sensors, strain gauge load cells are the most commonly used type.

Except for certain laboratories where precision mechanical balances are still used, strain gauge load cells dominate the weighing industry. Pneumatic load cells are sometimes used where intrinsic safety and hygiene are desired, and hydraulic load cells are considered in remote locations, as they do not require a power supply...

Industrial Internet of Things or IIoT is a prerequisite for industries looking to embrace digital transformation. It is through this connected ecosystem that businesses gain increased visibility in their processes, ensure equipment uptime, perform predictive maintenance, and increase productivity and profitability.

However, realizing these benefits through smart factory initiatives is more challenging than it may seem. The most common obstacle is collecting operational data from legacy machines and communicating that data to the cloud...

Industrial automation systems are expensive assets, designed to offer reliable performance for years. Typically, industrial systems last for decades. It is impractical than to discard these existing systems when new technology becomes available.

So, how do businesses remain competitive and efficient if they cannot afford to adopt new technology? The scenario is common today for most industrial setups...

A thermocouple is a sensor for measuring temperature. This sensor consists of two dissimilar metal wires, joined at one end, and connected to a thermocouple thermometer or other thermocouple-capable device at the other end. When properly configured, thermocouples can provide temperature measurements over wide range of temperatures.

Thermocouples are known for their versatility as temperature sensors therefore commonly used on a wide range of applications...

Technically speaking, a data logger is any device that can be used to store data. This includes many data acquisition devices such as plug-in boards or serial communication systems which use a computer as a real time data recording system. Most instrument manufacturers, however, consider a datalogger a stand alone device that can read various types of electrical signals and store the data in internal memory for later download to a computer.

The advantage of data loggers is that they can operate independently of a computer, unlike many other types of data acquisition devices. Data loggers are available in various shapes and sizes...