Bimetallic, manometric, liquid (glass) thermometers. Indicating thermometers WIKA A43 - Bimetal thermometer for heating systems

One of the anachronisms that has migrated into the life of a modern person is a street thermometer, which, according to an established habit, is screwed or glued to a window frame in order to determine the air temperature on the street. Why an anachronism and why is it not needed? We will try to tell in the article brought to your attention. Street thermometers on plastic windows are installed everywhere. In most cases, without even thinking about whether it makes sense to waste time on this useless activity.

But, if such a need exists for a certain category of citizens, we, of course, will answer questions about how best to do this.

Do I need a thermometer behind a plastic window?

From the time of their invention and until the recent historical past, street thermometers, at the very least, coped with their duties - to show the air temperature on the street. Just like today and fifty and a hundred years ago, they shamelessly lied. This was due not to the peculiarities of the devices themselves, but to the fact that they were installed anywhere and anyhow. Therefore, there were cases of disputes about how cold or hot on a particular day. The debaters simply forgot that the outdoor thermometers, on whose readings they were guided, were placed in different conditions. For some, it is on a window illuminated by the Sun in the morning, for others it is on the frame of an eternally shaded balcony, and for others it is on a column in the courtyard of a private house.

In the 21st century, the need for this device outside the window has completely disappeared. Almost everyone has a cell phone or smartphone, which with one touch can show on the display absolutely accurate and objective data on air temperature, humidity, wind strength and "subjective" feelings of the weather, if necessary, adding to the readings the value of atmospheric pressure and precipitation forecast for the next day or a whole week.

But the force of inertia of thinking and habits is so strong that instead of getting out of bed to find out what the weather is waiting for you on the street, many wander to the street thermometer outside the window and find out with joy or sorrow that the weather is not at all like that outside, what they dreamed about in their dreams.

A little about thermometers (thermometers)

Traditionally, in everyday life, two types of thermometers are used to measure the air temperature on the street: alcohol and bimetallic.
The former is a hermetically sealed capillary tube with colored alcohol, which, as the temperature rises or falls, either expands or contracts, sliding along the capillary along the applied metric scale.

Bimetallic thermometers are a spring consisting of an alloy of two metals with a different coefficient of expansion, at the end of which an arrow is installed. When heated or cooled, the spring either contracts or uncoils. In accordance with this, the arrow located at the end of such a spring also moves, showing a certain value on an arcuate degree scale.

The third type of outdoor thermometers are electronic, which receive signals from an outdoor sensor and transmit it to an electronic device that displays the temperature digitally on an LCD display.

At present, these three models are distributed approximately equally and serve as the subject of endless complaints from the owners about the quality of the instruments and the reason for the mathematical calculations of the arithmetic mean, in the event of a discrepancy between the readings on two or more thermometers.

The most accurate readings under all equal conditions are given by electronic thermometers. Since their remote heat-measuring elements undergo stricter metrological control (except for Chinese ones) and their temperature sensors can be attached in places inaccessible to direct sunlight.

Bimetallic thermometers differ in the least degree of reliability. The middle and most popular position among the population is occupied by alcohol thermometers. But you should take into account the age of the device. The longer he serves you, the more he deceives you. This is due to the gradual evaporation of the alcohol liquid and its condensation in the upper part of the capillary.

As a result, the column of colored liquid becomes gradually shorter and shorter, and the temperature outside is getting “lower” and “lower”.

What to do so that the thermometer does not lie?

It is almost impossible to obtain absolutely reliable information about the air temperature from an outdoor thermometer located on the frame of a plastic window. The first reason is the thermal radiation emanating from the house. If it is known that up to 30% of heat is lost through windows, then, accordingly, the radiated heat will make adjustments to the thermometer readings in the direction of increasing temperature.

The second factor is the incorrect installation of the thermometer. They are usually mounted on windows that provide the easiest and most permanent access. These are kitchen windows or windows in the bedroom. At the same time, few people think about checking the compass or the 2GIS program before installing the thermometer and determining in which direction your plastic windows are oriented. If in the east - the thermometer will "lie" in the morning, if in the west - in the late afternoon, if in the south - throughout the day. It has to do with solar activity. Even in cloudy weather, the southern wall of the house will warm up more and the heat emanating from it will not allow your thermometer to show a reliable temperature.

The most accurate, as far as possible, readings are given by outdoor thermometers located on the north side. They are objective because they are not affected by direct sunlight.
The third mistake that contributes to incorrect readings is ignoring the shielding requirements of the thermometer. It must be covered from the outside with a reflective screen that will protect it from the influence of direct solar radiation.

The fourth condition is the presence of a sufficient gap between the thermometer and the wall (not even the frame or glass) of the house.
It follows from this that if you do not observe these conditions, you will always receive very approximate readings in the range of +/- 3-5 ° C.

Installing a thermometer

If the above arguments did not convince you, and you still want to attach a thermometer outside your window, then carefully consider its choice. As already noted, bimetallic thermometers give the largest errors. This is due to the fact that it is very difficult to select and calibrate the scale for each specific spring located inside the device. It is enough to deviate the thickness of one of the strips of metal by a few microns so that the readings of the two thermometers differ. In mass production, no one makes their own scale for a particular spring. Therefore, the readings of thermometers are inaccurate.

The most common alcohol thermometers can serve you for many years, but every year their readings, as the liquid evaporates, will differ in the direction of “lowering” the temperature. When choosing an alcohol thermometer, one should strive to buy a device with the longest possible capillary tube. Numerous souvenir thermometers, equipped with paper scales inside the flask, are not initially calibrated and show the temperature with large errors.

If you opt for an electronic weather station, then its choice will depend solely on your financial capabilities and the number of functions that the device can perform.

It is best to fix the thermometer not on the frame of a plastic window, since reliable fastening is possible only by mechanical screwing with plastic screws. And spoiling the profile for the sake of installing a thermometer is hardly worth it. You can glue the thermometer, after washing and degreasing the PVC profile, on double-sided tape, but it is very short-lived and one day you may not find the thermometer outside your window, the reason for this may be birds, especially curious titmouses that are ready to perch on any surface .

Can be bonded with transparent construction adhesives used for PVC plastics or transparent plumbing silicone sealant. It is not recommended to glue with Sekunda adhesives containing cyanoacrylate. Despite its outstanding qualities in terms of the speed and strength of the initial setting, the substance itself decomposes rather quickly under the influence of air humidity and UV radiation and after about a year the adhesive ceases to hold.

Therefore, the best option would be to fix the thermometer on the wall of the house on an external bracket with fixing it with small screws or nails. Do not forget to supply the thermometer with the simplest home-made screen made of foil material, which will protect it from direct sunlight. The thermometer should be fixed on the side of the window sash that does not open, so that the sash that is slightly open for ventilation does not make adjustments to the readings of the device due to the warm air from the room.

This section presents manometric thermometers (gas-THP, condensation (vapor-liquid)-TKP) showing: TGP-100M1, TKP100(100S), TKP60-3M, TKP-60S, etc.

TGP-100-M1- thermometer showing gas (T up to 400C, diameter 100mm, 1; 1.5%, capillary from 1.6 to 25m, bulb 160-400mm).
TKP-100-M1- a thermometer showing condensation (T up to 300C, diameter 100mm, 1; 1.5%, capillary from 1.6 to 25m, bulb 160-400mm).
TKP-60/3M- vibration-resistant manometric thermometer (diameter 60mm, 1; 1.5; 2.5%, capillary from 1.6 to 25m, thermocylinder 100, 125mm, vibration resistance 5-700Hz, IP53).
TKP-60/3M2- vibration-resistant manometric thermometer (diameter 60, 100, 160 mm, accuracy class 2.5%, capillary from 1.6 to 16 m, bulb 100 mm).
TKP-60S- thermometer manometric showing condensation (diameter TKP60 - 60mm, capillary from 1.6 to 10m).
TKP-100S- a manometric indicating condensation thermometer (TKP100 diameter - 100mm, capillary from 1.6 to 10m).

It is also possible to supply other brands of manometric indicating condensation and gas thermometers.

The operation of thermometers, in modes with pressures of the measured medium exceeding the norms established for them, is possible only with the use of protective sleeves (up to 25 MPa (250 kgf/cm2)).

Time-tested technologies are used for mechanical temperature measurement. Such as bimetal and manometric measurement principles, made of various materials with scale ranges from -100 to +500 °C in various accuracy classes and response times. Options for process connections, diameters and stem lengths allow you to choose the right solution for any application.

WIKA mechanical indicating thermometers, with capillary, provide easy and comfortable handling. All WIKA thermometers can be equipped with a thermowell if required. Various models of thermomanometers are also available for selection - a combined pressure and temperature meter (100.12, MFT, etc.).

WIKA A43 - Bimetal thermometer for heating systems

The bimetal thermometer model A43 has been designed for simple measurements in heating systems.

The design is prefabricated, thanks to which various combinations of body materials, nominal sizes, measuring ranges and stem lengths can be made. This allows you to save the customer's design, without making additional changes.

A thermowell is included as standard with the A43, which allows measurements up to a maximum pressure of 6 bar.

Model A43 is manufactured with accuracy class 2 in accordance with EN 13190, which ensures the required indication accuracy for heating technology.

WIKA 46 - Bimetal thermometer with pocket, range up to +120 °C

The model 46 bimetal thermometer is primarily used in heating, air conditioning and refrigeration systems for monitoring process temperatures.

To measure the temperature, a bimetal thermometer is installed in the process together with a thermowell. On the one hand, this protects the thermometer from damage, and on the other hand, it does not require cleaning the heating system to replace it.

WIKA 50 Bimetal thermometer with pocket, range up to +200 °C

Thermometer, Model 50 is designed for use in heating, air conditioning, ventilation and refrigeration technology, for measuring ranges up to 200 °C. To measure the temperature, a bimetal thermometer is screwed into a protective sleeve and placed into the process. This protects the thermometer from damage, on the one hand, and on the other hand, it is not necessary to replace it.
you need to stop the process.

WIKA 52 - Bimetal thermometer for axial and radial process connection, range up to +500 °C

The bimetallic thermometer of this series was designed specifically for installation in pipes and tanks.

Bimetallic thermometer uses bimetallic plates as a measuring element. Bimetal plates are metals that have different coefficients of linear expansion when measuring temperature. They are twisted into a helical spiral, the other end is fixed to the movable axis. When measuring temperature, the spiral rotates in proportion to the magnitude of the change, the transmission occurs through the axis and then through the tube-sector mechanism to the arrow.

WIKA 70 - Liquid thermometer with capillary, stainless steel case

Thanks to its versatile design, this type of liquid thermometer has found wide application in mechanical engineering, the refrigeration industry and air conditioning systems. A liquid thermometer can be installed at almost all measuring points. The capillary model is used for measurements at points that are difficult to access or that are at a considerable distance.

The body, capillary and stem are made of stainless steel. For optimal adaptation to the measuring process, various capillary lengths are available, up to a maximum length of 10 mm, and connection forms.

WIKA 32 - Industrial glass V-shaped thermometer

Industrial glass thermometers - Model 32 are mainly used in various industries such as mechanical engineering, energy, refrigeration.

A feature of these thermometers is high accuracy and durability (due to the absence of mechanical wear parts).

WIKA 100.12 - Thermomanometer, pressure and temperature measurement in one device

The thermomanometer with bimetal system is installed directly at the measuring point through the stem. The presence of the valve allows you to unscrew the measuring device without draining the water from the heating system. Thanks to the combination of pressure gauge and bimetal thermometer, the measuring instrument can be used in a wide range of applications.

WIKA IFC - Manometric thermometer with capillary

Capillary thermometer model IFC is a universal manometric thermometer for mechanical engineering, refrigeration and food industries, as well as heating, ventilation and air conditioning systems.

Temperature measurement occurs due to the expansion of the thermometric liquid in the capillary.

This type of capillary thermometer is used to measure temperature in hard-to-reach places, as well as in places that are at a considerable distance.

Thanks to its simple design and plastic housing, the IFC capillary thermometer is an inexpensive and very reliable measuring instrument.

WIKA TF58, TF59 - Manometric thermometer with capillary

Liquid thermometer, models TF 58 and 59, are drum-type measuring instruments.

Different versions have different accuracy, scale range, dimensions, mounting and panel frame design.

WIKA MFT - Thermomanometer with remote line and capillaries, pressure and temperature measurement in one device

The thermomanometer is installed in the panel and allows you to measure pressure and temperature simultaneously. The thermomanometer has a compact design with a front flange and side latches, making it easy to install and integrate into the ergonomics of dashboards. The capillary simplifies the possibility of remote mounting of the indicating part of the device and the measuring point.

The thermomanometer has a Bourdon tube as a sensitive element for measuring pressure. A manometric thermometer filled with liquid is used to measure temperature. A liquid-filled pressure gauge thermometer converts the change in pressure within a closed system of hollow tube and capillary into temperature and transmits this rotation to the pointer.