Relative the dielectric constant
Relative permittivity environment ε is a dimensionless physical quantity that characterizes the properties of an insulating (dielectric) medium. Associated with the effect of polarization of dielectrics under the action of electric field(and with the dielectric susceptibility of the medium characterizing this effect). The value of ε shows how many times the interaction force of two electric charges in a medium is less than in vacuum. The relative permittivity of air and most other gases under normal conditions is close to unity (because of their low density). For most solid or liquid dielectrics, the relative permittivity ranges from 2 to 8 (for a static field). The dielectric constant of water in a static field is quite high - about 80. Its values are large for substances with molecules that have a large electric dipole. The relative permittivity of ferroelectrics is tens and hundreds of thousands.
There is also a version with a coaxial rod, especially suitable for measuring media with poor reflective properties. Reflexometric waveguides are proven and affordable solutions, especially in large tanks. However, problems can be caused by the contact of the measured medium with the waveguide. In addition, when using a ball valve, it is possible to completely separate the sensor from the inside of the container.
Therefore, it is possible to install and remove the sensor without emptying the tank. It is ideal for measuring at extremely low operating temperatures. It doesn't matter if the environment is aggressive or corrosive. The company has special sensors for measuring the interface between liquid media in separators and for separating bottled media in pharmaceutical and petrochemical plants. It is able to detect where the interfaces of the two liquids in the container are to ensure accurate and reliable separation of the bottom during filling and furthermore to separate the emulsion as a result of their contact.
Measurement
Relative permittivity of a substance εr can be determined by comparing the capacitance of a test capacitor with a given dielectric (C x) and the capacitance of the same capacitor in vacuum (C o):
Practical use
The permittivity of dielectrics is one of the main parameters in the design of electrical capacitors. The use of materials with a high dielectric constant can significantly reduce the physical dimensions of capacitors.
The system continuously measures the probe's impedance interface rod, which gives a signal that is proportional to the interface height as the probe moves relative to the reference point. The impedance value represents the chemical and physical properties medium and the length in which the medium wets the active part of the probe. The impedance then changes depending on how the media interface is moved along the probe. This signal can be either relative or absolute position of the interface. Thus, moving the interface from 0 to 100% is converted to a 4 to 20 mA output signal.
The capacitance of capacitors is determined:
Where εr is the permittivity of the substance between the plates, ε o- electric constant, S- the area of the capacitor plates, d- distance between plates.
The permittivity parameter is taken into account when designing printed circuit boards. The value of the dielectric constant of the substance between the layers in combination with its thickness affects the value of the natural static capacitance of the power layers, and also significantly affects the wave resistance of the conductors on the board.
Bar probe for fluid interface measurement. Flow sensor for fluid interface. Flow sensor for measuring petrochemical products. Smoke detection sensor. Action. Due to their ability to work on a long-term basis without any problems, these switches are very well used in warehousing, but also in other industrial applications.
The switches are designed to determine the position of the volume and level of dust in all types of containers. Thanks to the wide range of types and variants of these limit switches, it is possible to choose the right tool for a given task or to make an individual switch according to customer requirements. 
Of course, there is a wide range of threads or flanges for process connections, as well as a range of so-called rotating blades. In cases where a very fast switch response is required, such as level position detection in bins, the speed motor version is five rpm.
Frequency dependency
It should be noted that the permittivity depends to a large extent on the frequency of the electromagnetic field. This should always be taken into account, since handbook tables usually contain data for a static field or low frequencies up to several units of kHz without indicating this fact. At the same time, there are also optical methods for obtaining the relative permittivity from the refractive index using ellipsometers and refractometers. The value obtained by the optical method (frequency 10 14 Hz) will differ significantly from the data in the tables.
Probes can be equipped with electronics according to customer's request. Limit rotary switches are designed to determine the position of the layers building materials and aggregates, various materials in chemical industry, food products, animal feed, synthetic materials, woodworking, rubber and other industries. 
The switches are also available as a 2m or 1m rope and a 0.5m long pivot. To mention the cost-effective measurement of limit values for cement, limestone, crushed aggregate and coal.
Consider, for example, the case of water. In the case of a static field (frequency is zero), the relative permittivity under normal conditions is approximately 80. This is the case up to infrared frequencies. Starting around 2 GHz εr starts to fall. In the optical range εr is approximately 1.8. This is consistent with the fact that in the optical range the refractive index of water is 1.33. In a narrow frequency range, called optical, dielectric absorption drops to zero, which actually provides a person with a mechanism of vision in the earth's atmosphere saturated with water vapor. As the frequency increases further, the properties of the medium change again. The behavior of the relative permittivity of water in the frequency range from 0 to 10 12 (infrared) can be read at (eng.)
This lightweight material is often measured in dusty environments. Even here, the devices maintain sufficient measuring sensitivity. The reliability of the switches has also proved useful in measuring the level of quartz sand in the pressure drums. High pressure in combination with abrasive material requires a mechanically strong and sufficiently tight device. Less demanding applications include, for example, extreme measurements of the height of polystyrene granules, grain or even flour.
Customers can expect fast response to demand, high quality products, a wide range of products and consistent service. Employees with many years of experience will help in the selection and development of the right solution, even during installation and commissioning of the device. All supplied devices comply with current Czech and European standards.
Notes
see also
- Vacuum permittivity (electrical constant)
Dielectric Constant Values for Some Substances
| Substance | Chemical formula | Measurement conditions | The characteristic value ε r |
|---|---|---|---|
| Aluminum | Al | 1 kHz | -1300 + 1.3 10 14 i |
| Silver | Ag | 1 kHz | -85 + 8 10 12 i |
| Vacuum | - | - | 1 |
| Air | - | Reference conditions, 0.9 MHz | 1.00058986±0.00000050 |
| Carbon dioxide | CO2 | Normal conditions | 1,0009 |
| Teflon | - | - | 2,1 |
| Nylon | - | - | 3,2 |
| Polyethylene | [-CH 2 -CH 2 -] n | - | 2,25 |
| Polystyrene | [-CH 2 -C (C 6 H 5) H-] n | - | 2,4-2,7 |
| Rubber | - | - | 2,4 |
| Bitumen | - | - | 2,5-3,0 |
| carbon disulfide | CS2 | - | 2,6 |
| Paraffin | C 18 H 38 - C 35 H 72 | - | 2,0-3,0 |
| Paper | - | - | 2,0-3,5 |
| Electroactive polymers | − | − | 2-12 |
The dielectric constant environment - a physical quantity that characterizes the properties of an insulating (dielectric) medium and shows the dependence of electric induction on the strength of an electric field.
Compact ultrasonic level meter for continuous level measurement. This level meter is suitable for measuring the height of liquids and bulk materials. 
All necessary cables and adapters are located inside the transmitter and are included. An additional 4 to 20 mA signal is available on the transmitter. 
This provides easy and reliable radio transmission, also suitable for industrial environments, but does not require license registration or subscription registration.
It is determined by the effect of polarization of dielectrics under the action of an electric field (and with the value of the dielectric susceptibility of the medium characterizing this effect).
There are relative and absolute permittivities.
obstacles such as streets, railways, rivers and buildings can be easily crossed and at minimal cost. 
All supplied devices comply with the relevant Czech and European standards, and their reliability is confirmed by many years of operation in our country and abroad.
With a measuring range of up to 70 m and a wide temperature and pressure range, this level meter represents a new class of instrument for measuring bulk solids. Within three years he has built a very good name among clients all over the world. However, there is still room for measurement with a smaller measuring range in standard applications with normal operating conditions.
The relative permittivity ε is dimensionless and shows how many times the interaction force of two electric charges in a medium is less than in vacuum. This value for air and most other gases under normal conditions is close to unity (because of their low density). For most solid or liquid dielectrics, the relative permittivity ranges from 2 to 8 (for a static field). The dielectric constant of water in a static field is quite high - about 80. Its values are large for substances with molecules that have a large electric dipole moment. The relative permittivity of ferroelectrics is tens and hundreds of thousands.
However, the core of the device remains a proven method for measuring radar pulses with high signal sensitivity, which works with an echo estimation method optimized for measuring bulk materials. 
It is suitable for most standard applications where bulk materials are handled, from the food industry, through the storage of plastics, to the production and processing of building materials. The small, lightweight sensor is ideal for installation into existing mounting holes.
The absolute permittivity in foreign literature is denoted by the letter , in the domestic literature, the combination is mainly used ε ε 0 (\displaystyle ~(\varepsilon )(\varepsilon )_(0)), where is the electric constant. Absolute permittivity is used only in the International System of Units (SI), in which induction and electric field strength are measured in different units. In the CGS system, there is no need to introduce the absolute permittivity. The absolute dielectric constant (as well as the electric constant) has the dimension L −3 M −1 T 4 I². In units of the International System of Units (SI) : [ ε 0 (\displaystyle ~(\varepsilon )_(0))]= / .
Due to its two-wire connection, it can be easily chosen as a replacement for legacy systems, since existing cable lines can be used. The measurement results do not affect even strong fluctuations in dust and temperature. Possible questions can be found on site with the technical and commercial staff of the company with many years of experience in the field of industrial automation. 
Demonstration visits may be recommended to workers involved in measurement and regulation, for example, in the chemical, petrochemical, food, pharmaceutical, heating, cement, water and other industries.
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Generally speaking, the permittivity is a tensor determined from the following relations (the notation uses the Einstein convention):
D i = ε 0 ε i j E j (\displaystyle ~D_(i)=\varepsilon _(0)\varepsilon _(ij)E_(j)) D = ε a E (\displaystyle ~\mathbf (D) =(\boldsymbol (\varepsilon ))_(a)\mathbf (E) ) E = E 1 e 1 + E 2 e 2 + E 3 e 3 (\displaystyle ~\mathbf (E) =E_(1)\mathbf (e) _(1)+E_(2)\mathbf (e) _ (2)+E_(3)\mathbf (e) _(3))- electric field strength vector, D = D 1 e 1 + D 2 e 2 + D 3 e 3 (\displaystyle ~\mathbf (D) =D_(1)\mathbf (e) _(1)+D_(2)\mathbf (e) _ (2)+D_(3)\mathbf (e) _(3))- electric induction vector, ε a = ε 0 ((ε a) i j) (\displaystyle ~(\boldsymbol (\varepsilon ))_(a)=\varepsilon _(0)((\varepsilon _(a))_(ij))) is the absolute permittivity tensor.More detailed information the location of the demo vehicle can be obtained from your regional sales representatives or directly from the company's headquarters. The need for such a device is a perfect seal. Ammonia is a colorless, highly corrosive and irritating gas. Already in small concentrations, the environment makes it a pungent odor. It also dissolves easily in water. Ammonia solution in water is highly alkaline and corrosive.
Ammonia storage tank: on the left in the bypass radar position sensor, directly in the container. Limit switch. Ammonia is used in many processes in the chemical industry. It serves as a starting material in the production of industrial fertilizers, but is also used in many chemical reactions. Therefore, high requirements are required for the design of level transmitters for measuring ammonia, whether it is anhydrous or its solution in water. Ammonia is usually stored in pressurized tanks equipped with a service pressure gauge and an independent safety switch.
E = E 0 e i ω t ⇒ ∂ E ∂ t = i ω E (\displaystyle ~\mathbf (E) =\mathbf (E) _(0)e^(i\omega t)\ \Rightarrow \ (\frac (\partial \mathbf (E) )(\partial t))=i\omega \mathbf (E) )
Measurement
Relative permittivity of a substance εr can be determined by comparing the capacitance of a test capacitor with a given dielectric (C x) and the capacitance of the same capacitor in vacuum (C o):
ε r = C x C 0 . (\displaystyle \varepsilon _(r)=(\frac (C_(x))(C_(0))).)Reflectometric level meters use the propagation of an electromagnetic pulse in a body immersed in a medium in a tank. Microwave impulses are reflected in the place where permissiveness changes environment? i.e. on the surface. The intensity of the reflected signal depends on the relative permissiveness of the medium: the higher the dielectric constant, the more intense the reflection. The time between the impulse sending and receiving the reflected impulse is estimated. For measuring ammonia, these levels are suitable because, unlike pulsed radar level meters, there is no signal attenuation when passing through ammonia vapor.
Practical use
The permittivity of dielectrics is one of the main parameters in the development of electrical capacitors. The use of materials with a high dielectric constant can significantly reduce the physical dimensions of capacitors.
Limit measurement with vibration switches
In addition, the process connection seal must be made from materials that do not emit ammonia. Since ammonia is a dangerous, poisonous substance, more stringent safety conditions must be observed when storing it. Therefore, as a rule, therefore, it is necessary to install reliable limit switches in tanks that provide a warning signal when a certain level is reached.The capacitance of capacitors is determined:
C = ε r ε 0 S d , (\displaystyle C=\varepsilon _(r)\varepsilon _(0)(\frac (S)(d)),)Where εr is the permittivity of the substance between the plates, ε o- electric constant, S- the area of the capacitor plates, d- distance between plates.
Due to the complete separation of the electronics from the measuring plug, there is no risk of ammonia getting into the electronics of the sensor, which will lead to its certain destruction. At the same time, it guarantees greater resistance to adverse operating conditions - temperature and pressure. For use with ammonia containers, it is important that the sensor process connection is absolutely tight so that the ammonia cannot dissipate it.
They are suitable for level measurement of liquids and bulk solids and are especially suitable for level measurement of aggressive liquids.The dielectric constant parameter is taken into account when developing printed circuit boards. The value of the dielectric constant of the substance between the layers in combination with its thickness affects the value of the natural static capacitance of the power layers, and also significantly affects the wave resistance of the conductors on the board.
