What is a thermometer and what is it used for
A thermometer is an instrument that shows the temperature of a liquid, gas, steam or surface. In industry and heating, temperature is, alongside pressure, the most important process parameter: it governs the safety of boilers and heat exchangers, product quality in the food and chemical industries and energy consumption in heating systems. Analogue thermometers are read directly on site and need no power supply, while electrical sensors (resistance thermometers and thermocouples) send a signal to the control system.
How industrial thermometers work
A bimetal thermometer has a measuring coil made of two metal strips with different coefficients of thermal expansion. When the temperature changes, the coil twists and turns the pointer directly, with no transmission mechanism, which makes the instrument robust and reliable. A glass thermometer works on the expansion of liquid in a capillary and offers high accuracy and long-term stability. A resistance thermometer measures the change in electrical resistance of a metal sensor with temperature, and a thermocouple measures the voltage generated at the junction of two dissimilar conductors, which is why it covers the highest temperatures, up to 1600 °C.
Types of thermometers in the Fadip range
Standard bimetal thermometers (TBAS back entry and TBRS bottom entry) have a black powder coated steel case and are designed for non-aggressive fluids under pressure.
All stainless bimetal thermometers (TBAN, TBRN) and every-angle stainless thermometers (TBZG), whose case can be rotated to the best reading position, are designed for aggressive media and aggressive environments.
Bimetal thermometers for heating (TBAS KT1S with brass pocket), capillary thermometers and thermo-manometers, which show temperature and pressure on a single dial, cover boilers, hot water cylinders and heat substations.
Glass thermometers in brass cases measure from -40 to +400 °C with accuracy class 1.0, while resistance thermometers and thermocouples provide an electrical signal for automation. For pipe surface temperature without cutting into the installation, use a clamp-on pipe thermostat.
How to choose a thermometer
Five parameters need to be defined. The measuring range should be chosen so that the working temperature falls in the middle third of the scale, where accuracy is highest and the instrument is not constantly running at its limit.
The dial size (63, 80, 100 or 160 mm) depends on the reading distance, and the connection position (back entry, bottom entry or every-angle) on the installation point.
The stem length and diameter (Ø6, Ø8, Ø10 or Ø12 mm) must ensure that the tip of the stem sits in the flow of the medium rather than in a dead zone near the pipe wall. The medium and pressure determine the material (steel or stainless steel) and whether a thermowell is needed, which also allows the thermometer to be replaced without draining the installation.
Technical specifications
Bimetal thermometers are made to EN 13190 with 80, 100 and 160 mm dials, in accuracy classes 1.0 and 2.0, for ranges from -20 to +400 °C and working pressures up to 40 bar without a thermowell (60 bar on request). The connection is fixed or sliding (adjustable), in brass or stainless steel, with the thread to order. The heating version comes with 63, 80 and 100 mm dials, class 2.5, for -20 to +120 °C and pressures up to 6 bar with a pocket and G1/2" connection. Resistance thermometers and thermocouples have an aluminium connection head and a G1/2, G3/4 or M20x1.5 thread, and resistance thermometers work at pressures up to 20 bar in ranges up to 400 °C.
Thermometer applications by industry
In heating and heat substations, thermometers and thermo-manometers monitor flow and return temperatures, boilers and hot water cylinders. The food, pharmaceutical and chemical industries use all stainless bimetal thermometers on reactors, pasteurisers and pipelines. Power generation, refineries and boiler making require thermometers with thermowells for steam and high pressures, while thermocouples are used in furnaces, on exhaust gases and in metallurgy. Resistance thermometers are the standard in automation, HVAC systems and cold stores, where an electrical signal is needed.
Thermometer calibration and servicing
Fadip operates a laboratory accredited by the Accreditation Body of Serbia to SRPS ISO/IEC 17025:2017, including temperature instruments. The scope covers liquid-in-glass thermometers and bimetal thermometers, so we issue calibration certificates for new and existing instruments. The recommended interval is 12 months, and more often for instruments exposed to vibration, thermal shock or used in safety functions.
Why buy from a manufacturer
As a manufacturer, Fadip supplies standard thermometers from stock and adapts the stem length, dial size, range, connection and material to the customer's requirements at short notice. Calibration and servicing are carried out in-house.
Alongside thermometers we offer pressure gauges, temperature transmitters and sensors for systems with an electronic signal, and digital indicators.
For a quotation, send us the measuring range, medium, pressure, dial size, stem length and connection. Our technical team will recommend a suitable thermometer within 24 hours. Contact us.
