pressure in gaseous and liquid media, among the most important indicators, the measurement of which is required for the maintenance and communication technology systems.By working objects include various filters, pipeline systems, devices for air conditioning and ventilation.Using a differential pressure gauge, the user reveals not only the characteristics of the current pressure, but also an opportunity to capture the difference between the dynamic performance.Knowledge of these data facilitates control of the system and increases the reliability of operation.In addition, differential pressure gauges are used for measuring the flow of liquid, gas or compressed air.
The principle of
Most gauge technology definitions and data calculation based on deformation processes in special measuring units, for example, in the bellows.This element acts as an indicator, the perceived pressure drops.And the inverter unit becomes the difference in pressure readings - the user is informed via the indicator arm moving on the device.In addition, data can be presented in Pascals, covering the whole measuring range.This method of displaying information, for example, provides a differential pressure Testo 510, which is in the process of measurement eliminates the need to keep it in his hand, as on the back of the unit are special magnets.
in mechanical devices as the main indicator of the location of the arrow is controlled by a lever system.The movement of the index takes place until such time as the system drops will not cease to influence a certain strength.A classic example of this system shows the differential pressure gauge DM Series 3538M, which provides proportional transformation of the delta (difference pressure), and provides a result of the operator in the form of unified signal.
Classification
Given the complexity of the processes pressure measurements, characteristics of working environment and further transformation, there are several variants of differential pressure to work under different conditions.By the way, differential pressure, the operating principle of which is largely determined by its design, on the device is focused on the possibility of applying in a particular environment - hence this is done and classification.Thus, manufacturers produce the following models:
- Group liquid differential pressure, which includes float, bell, tube and ring modification.They measurement process is based on indicators of liquid column.
- Digital differential pressure gauges.Considered the most functional, as they provide the ability to measure not only the characteristics of the pressure drop, but also the speed of the compressed air flow, humidity and temperature indicators.A good representative of this group is the differential pressure Testo, which is also used in the environmental monitoring system, in wind and environmental studies.Category
- mechanical devices.It bellows and diaphragm version capable of measuring performance by monitoring the pressure-sensitive element.
Two-pipe model
These instruments are used for measuring the pressure and determination of the differences between them.This device level is visible, which is generally in U-shape.According to the construction of such a differential pressure gauge is a unit of two vertical communicating tubes, which are fixed on a wooden or metal base.A compulsory component of the device is the plate with scale.In preparation for the measurement of the pipe is filled with the medium.
Next to one of the tubes starts feeding the measured pressure.Simultaneously, the second pipe communicates with the atmosphere.During the measurement of the delta, both measured pressure test tube.A two-tube differential pressure gauge with liquid filling is used for measuring vacuum pressure of non-aggressive gases and air pollution.
monotube model
monotube differential pressure gauges are commonly used when you want to get the result of high accuracy.In such arrangements and applies a vessel which is pressurized with the largest coefficient.Only the tube is fixed to the plate with a scale showing difference data, and communicates with the atmospheric environment.In the process of measuring the differential pressure interacts with it the smallest of pressures.Working medium is poured into a differential pressure gauge until until it reaches zero.
Under pressure certain percentage of fluid flows into the tube from the vessel.As the volume of fluid that has moved into the measuring tube corresponds to the volume withdrawn from the vessel, single pipe manometer provides a measure of the height of a single liquid column.In other words, the measurement error is reduced.Nevertheless, this type of devices and are not free from drawbacks.
deviations from the optimal values may be due to thermal expansion in the measuring instrument components, the density of the working environment and other errors, which, however, are common to all types of pressure switches.For example, a digital differential pressure gauge, even after adjusting for indicators of density and temperature coefficients as a certain threshold of error.
Diaphragm differential pressure gauges
main subtype of the mechanical differential pressure gauge, which is also divided into devices with metal and non-measuring elements.In devices with a flat membrane of metal calculations are based on the fixation characteristics of deflection in the measuring component.Common and differential pressure gauge, in which the membrane acts as a partition wall for the cameras.At the time of the deformation reaction force formed cylindrical coil spring discharged measuring element.So there is a comparison of two different pressure values.
also some modifications of membrane devices are provided with protection against unilateral effects - This feature allows the design to use them to measure the performance of overpressure.In spite of the active introduction of electronics industry in general metrology, measuring membrane remained in demand and even indispensable in certain areas.For example, high-tech differential pressure gauge DMC-01M digital type, in spite of the ergonomics and accuracy, has a number of restrictions on the use in environments where devices can be operated membrane.
Bellows version
In such models, the measuring element is a corrugated metal box, complete with a spiral spring.The plane of the bellows unit is divided into two parts.We have the greatest impact on the pressure chamber outside the bellows, and the least - the internal cavity.As a result of different pressure forces the sensor is deformed in accordance with a value proportional to the desired figure.This is the classic differential pressure gauges, showing the results of measurements of the arrow on the dial.But there are other members of this family.
Other mechanical versions
Less common ring, float and bell measuring device the differential pressure.Although some of them are relatively accurate besshkalnye recorders and models, as well as devices with electrical contact devices.Data are provided in the remote again by telecommunications or by pneumatics.To determine the expenditure indicators based on variables differences also produce mechanical devices with a summing and integrating additions.
Digital differential pressure gauges
Devices of this type in addition to the basic functions of measuring the difference in pressure can define dynamic performance environments.Such devices are indicated by marking DMC-01M.Digital Differential Pressure Gauges, in particular, is used in the control systems of ventilation of production facilities, allows to calculate parameters of gas consumption, taking into account the temperature adjustment, and to keep records of the average cost of the measured positions.The device is equipped with a microprocessor that automatically keeps a record of the measurements and accumulation of information on the gas duct.All received information about the results of the displayed.
Recommendations for choosing
Transactions with pressure indicators require the use of a reliable device that best meets specific conditions.In this regard, it is important to determine the list of functions to be performed by the device.For example, differential pressure Testo 510 is able to provide accurate readings with temperature compensation and to provide data on the digital display.In some cases, a signaling model, so you should take into account the availability of this option.
For the most accurate data in advance is necessary to compare the characteristics of the device with the ability to operate in a particular work environment.Not all devices can be used in oxygen, ammonia and freon atmospheres.At the very least, their accuracy may be low.
