As an important measuring instrument in the industrial field pressure transmitters rs485 has been widely used in thermal power, nuclear power, chemical industry, steel, aerospace and other fields. Because the output signal of the sensor is varied, in order to enhance the versatility of the sensor in practical applications and simplify the transmission and recording of the signal, usually need a circuit to convert the output signal into a standard signal. Pressure transmitter rs485 is a fluid pressure sensor measurement signal into a standard signal device. Pressure transmitters are mainly divided into adiabatic pressure transmitters, gauge pressure transmitters and differential pressure transmitters and other types. Absolute pressure transmitters are used in applications where atmospheric pressure cannot affect the measurement process, such as vacuum distillation columns. Gauge pressure transmitters use atmospheric pressure instead of absolute vacuum and are used in a wider range of applications. Differential pressure transmitters are used to measure pressure differences.
Differential pressure transmitter in addition to measuring the differential pressure value of the two measured pressures, it can also be used with a variety of other throttling instrumentation to measure the flow rate, can be directly measured by the level of the pressurized container and atmospheric pressure container level as well as pressure and negative pressure.
Pressure Transmitters rs485 and Differential Pressure Transmitters rs485 are explained from the term alone is the measurement of pressure and the difference between the two pressures, but they indirectly measure a lot of parameters. Such as pressure transmitters rs485, in addition to measuring pressure, it can also measure the liquid level inside the container equipment. When measuring the liquid level in an atmospheric pressure vessel, a pressure transmitters rs485 is required. When measuring the level of pressurized containers, it is necessary to use two pressure transmitters, that is, a measurement of the lower limit value, a measurement of the upper limit value, the output signals of the two pressure transmitters for subtraction operation, you can measure the level, the general selection of differential pressure transmitters. It can also be used to measure the density of the medium in the case of constant level and pressure in the vessel equipment. pressure transmitters rs485 can do a wide range of measurements, generally from the absolute pressure of 0 can be done to 100MPa.
Selection Principles of Pressure/Differential Pressure Transmitter
Selection of pressure and differential pressure transmitter is usually based on installation conditions, environmental conditions, instrument performance, economy and application media and other aspects of comprehensive consideration. Practical applications can be divided into direct measurement and indirect measurement; its use in process measurement, process control and device interlock. Common pressure and differential pressure transmitters are common pressure transmitters, differential pressure transmitters, single flange transmitters, double flange transmitters, inserted flange transmitters and so on.
Selection of pressure/differential pressure transmitter RS485:
(1) the measurement range, the required accuracy and the function of the measurement: in order to ensure the accuracy of pressure measurement, the minimum pressure measurement value should be higher than 1/3 of the measurement range of the pressure gauge; for the occasions that require long-distance measurements or high requirements for the accuracy of the measurement, pressure transmitter rs485 or pressure and differential pressure transmitters should be selected;
In the case of low requirements for the accuracy of the measurement, the resistive or inductive, Hall effect type can be selected Remote pressure gauge.
(2) measuring instrument surface to the environment: such as petrochemical industrial environment, the presence of combustible (toxic) and explosive hazardous atmospheres, high ambient temperatures, etc.; pressure transmitter rs485, pressure switches should be based on the installation of explosion-proof requirements of a reasonable choice.
(3) the physical and chemical properties and state of the measured medium: such as strong acids, strong alkalis, viscous, easy to solidify and crystallize and gasification conditions.
(4) Changes in operating conditions: e.g. changes in medium temperature, pressure, concentration. Sometimes also take into account from the start to the parameters to reach normal production, the gas phase and liquid phase concentration and density changes;
(5) The structure, shape, size of the object being measured container, container equipment accessories and a variety of import and export material orifices should be considered: such as towers, solution tanks, reactors, boiler steamer, vertical tanks, spherical tanks and so on.
(6) engineering instrumentation selection to have a unified consideration: the requirement to minimize the variety of specifications, reduce spare parts, in order to facilitate the management.
(7) The actual process situation: should consider the object to be measured belongs to which category of equipment. Such as tanks, tanks, tank volume is small, the measurement range will not be too large, tank volume is larger, the measurement range may be larger.
(8) but also look at the physical and chemical properties of the medium and the degree of cleanliness, the preferred conventional differential pressure transmitter rs485 and float level transmitter, but also to contact the media part of the material selection; and for some suspensions, foams and other media can be used in a single-flange differential pressure transmitter. Some easy to precipitate, easy to crystallize with the insertion of double-flange differential pressure transmitter rs485.
(9) for some high-viscosity media level and high-pressure equipment level, due to the equipment can not open the hole, you can choose the radiation level meter to measure.
1, Pressure Transmitters RS485 measure what kind of media, or media properties.
Viscous liquid, mud will plug the pressure interface, solvents or corrosive substances will not destroy the transmitter, to be precise, will not destroy the material in direct contact with the medium. These factors will determine the pressure transmitter in contact with the media where the use of what materials, or whether to choose a direct isolation membrane.
2, Pressure Transmitters RS485 measurement range
This measurement range is one of the key in the purchase process, which affects the price. Then first determine the maximum value of the measured pressure in the system, generally speaking, you need to choose a transmitter with a pressure range of about 1.5 times larger than the maximum value. This is mainly because in many systems, especially water pressure measurement and processing, there are peaks and continuous irregular up and down fluctuations, and such momentary peaks can destroy the pressure sensor. Continuously high pressure values or slightly exceeding the calibrated maximum value of the transmitter can shorten the life of the sensor, and in doing so can also degrade the accuracy. A snubber can then be used to reduce the pressure burr, but this reduces the response speed of the sensor. Therefore, when selecting a transmitter, it is important to give due consideration to the pressure range, accuracy and its stability.
3, Pressure Transmitters RS485 ambient temperature range
Usually a transmitter will be calibrated for two temperature segments, one of which is the normal task temperature, the other is the temperature compensation field, the normal task temperature field refers to the temperature field of the transmitter in the task form is not destroyed when the temperature field in excess of the temperature compensation field can not reach the use of its functional objectives. Functional objectives.
Also consider: power supply form, voltage value, pressure tube (bellows) material, output form.
4, the output form is how
mV, V, mA and frequency input digital inputs, the choice of what kind of input depends on a variety of factors, including the transmitter and the fragmentation of the controller or monitor between the interval, whether or not there is a “noise” or other electronic interference signals, whether or not the need to reduce the device, reduce the position of the device and so on. For many OEM devices with short distances between the transmitter and the controller, the mA input transmitter is the most economical and useful way to deal with the problem.
If you need to reduce the input signal, it is best to use a transmitter with built-in reduction. On the long-distance transmission or the existence of strong electronic interference signal is best to use mA-level input or frequency input.
5, the type of output form to determine the choice of what kind of excitation voltage
Many transmitters have a built-in voltage regulator installation, and therefore its power supply voltage field is larger. Some transmitters are quantitative configuration, the need for a stable task voltage, therefore, the task voltage to determine whether the use of sensors with a regulator, the choice of transmitter to consider the task voltage and fractional cost.
6, Pressure Transmitters RS485 accuracy needs to be how much, the company’s maximum accuracy of up to 0.075%
determine the accuracy of non-linearity, hysteresis, non-repeatability, temperature, zero bias scale, the impact of temperature. But mainly by the nonlinearity, hysteresis, non-repeatability, the higher the accuracy, the higher the price. ARTang’s high accuracy pressure transmitter price guarantees a good price.
7, the need for interchangeable transmitters
Determine whether the required transmitter can be adapted to multiple use of the system. This is generally important, especially for OEM products. Once the product is delivered to the customer then the customer used to calibrate the cost is quite large. If the product is interchangeable, then changing the transmitter used will not affect the effectiveness of the entire system.
8, Pressure Transmitters RS485 encapsulation problems
transmitter encapsulation, often easily overlooked is its rack, but this point in the later use will gradually reveal its defects. In the purchase of transmitters must think about the future mission environment of the transmitter, how humidity, how to install the transmitter, there will be no intense impact or vibration.
9, Pressure Transmitters RS485 overtime task after the need to maintain the stability of
most of the transmitter in the experience of excessive tasks will occur after the “drift”, so it is necessary to understand the stability of the transmitter before the purchase of this task after the fact can increase the future use of all kinds of trouble will be shown.
10, in the transmitter and other electronic equipment between the use of what kind of connection
whether the need to use a short distance connection? If the use of long-distance connection, can we need to use a connector?
