Technical Learning

Origin Story of the RTD / Pt100

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)...

Common Techniques to Calibrate Thermocouples

Temperature measurement is possible through several means. We commonly use thermometers for measuring temperature. However, for precision measurements, where even a small spike in temperature requires to be recorded, we use advanced forms of measurement devices like thermocouples. Thermocouples are measurement devices that can read very slight temperature changes. Hence, they are widely used in applications where accuracy is of utmost importance.

However, like any measurement device, the efficiency of thermocouples will deteriorate overtime under constant use. At this point, the thermocouple needs recalibration...

An Introduction to Industrial pH Measurement

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...

What is a mass flow meter and how does it work?

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...

What is a Signal Conditioner?

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...

RTD Pt100 vs Thermocouple

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...

What Are Common Applications for Thermocouples?

Thermocouples are the most widely used temperature sensors on the planet due to their combination of wide temperature capabilities, ruggedness, and low cost. Thermocouples are used in applications that range from home appliances to industrial processes, to electric power generation, to furnace monitoring and control, to food and beverage processing, to automotive sensors, to aircraft engines, to rockets, satellites and spacecraft.

When it comes to high temperatures, small size, fast response, high vibration or shock, most times you will find thermocouples providing the temperature measurements.

What are Infrared Temperature Sensors?

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...

What is a Type K Thermocouple?

Pressure Transducers and Transmitters

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...