As a precision instrument, pressure transmitter plays an important role in the petroleum and petrochemical industry. The transmitter can not only convert some commonly used quantities into the required amount of electricity, but also amplify some commonly used quantities. In the current industry, from the perspective of function, the transmitter can be divided into pressure transmitter, integrated temperature transmitter, liquid level transmitter and so on. In the petroleum and petrochemical industry, pressure transmitters are often used in a wide range of applications and applications.
The pressure transmitter has the advantages of reliable operation, stable performance, convenient installation and use, small size, light weight and high performance-price ratio. Widely used in various industrial self-control environments, involving water conservancy and hydropower, railway transportation, intelligent building, production automation, aerospace, military, petrochemical, oil well, electric power, ship, machine tool, pipeline and many other industries, suitable for measuring liquid, gas or steam The level, density and pressure are then converted into a 4-20 mADC signal output.
First of all, the parameters that must be seen when purchasing a pressure transmitter are: pressure range, range, measuring medium, mounting method, threaded flange clamp, etc., installation size, temperature, whether with display, whether with HART protocol, only type, output Type, current output or voltage output, explosion-proof grade, degree of protection, with mounting accessories, mounting bracket.
Secondly, it is also necessary to pay attention to the environment in which the selected pressure transmitter needs to be measured. For example, in the industrial environment of petroleum, there is a possibility of explosion and toxic gas, and the temperature is also extremely high. Therefore, before selecting a pressure transmitter, be sure to know which product to work under.
In addition, it is necessary to consider the size and shape of the object to be inspected, as well as the accessory equipment therein, otherwise the selected pressure transmitter is likely to be unsuitable for use, thereby causing some adverse effects.
After that, you have to choose according to the actual situation, you must know the size of the object being tested. Relatively speaking, the volume of the tank is relatively large, the range of measurement will increase, and the volume of the tank will be much smaller, so the measurement will be smaller. If some equipment does not have the conditions for opening, it also has the option of selecting other products for measurement.
1. What kind of media is measured by the pressure transmitter, or media properties.
Viscous liquids and mud can block the pressure interface. Solvents or corrosive substances will not damage the transmitter. To be precise, it will destroy the material that is in direct contact with the medium. These factors will determine what material is used where the pressure transmitter is in contact with the media, or whether a direct isolation diaphragm is selected.
2, The measurement range of the pressure transmitter
This measurement range is one of the keys in the purchase process, which affects the price. Then determine the maximum value of the measured pressure in the system. Generally, you need to select a transmitter with a pressure range that is about 1.5 times larger than the maximum value. This is mainly due to the fact that in many systems, especially water pressure measurement and processing, there are peaks and constant irregular up and down fluctuations, which can damage the pressure sensor. A sustained high pressure value or slightly exceeding the transmitter's calibrated maximum will shorten the life of the sensor, which will also reduce accuracy. A buffer can then be used to reduce the pressure glitch, but this will reduce the sensor's response speed. Therefore, the pressure range, accuracy and stability should be fully considered when selecting the transmitter.
3. The ambient temperature range of the pressure transmitter
Usually one transmitter will calibrate two temperature segments, one of which is the normal task temperature, the other is the temperature compensation field, and the normal mission temperature field is the time domain of the transmitter that is not destroyed in the mission mode. When it exceeds the temperature compensation field, it can not reach the functional target of its use.
The field of temperature compensation is a typical area that is smaller than the task temperature field. In this area, the task transmitter will definitely reach its intended functional target. Temperature changes affect its input in two ways, one is zero drift, and the other is affecting full-scale input. For example, full-scale, reading, full-scale in the temperature field, reading in the temperature compensation field, if there is no such parameter, will lead to uncertainty in the application. The change in the input of the transmitter is caused by a change in pressure or by a change in temperature. Temperature effects are the most complex part of understanding how to use a transmitter.
Also consider: power supply form, voltage value, pressure pipe (corrugated pipe) material, output form
4, The accuracy of the pressure transmitter needs to be large, the company's maximum accuracy can reach 0.075%
Determine the accuracy, nonlinearity, hysteresis, non-repetition, temperature, zero offset scale, temperature effects. But mainly by nonlinearity, hysteresis, non-repetition, the higher the accuracy, the higher the price. The company's high-precision pressure transmitters are guaranteed at an affordable price.
5. What is the output form?
mV, V, mA and frequency input digital input, the choice of input depends on a variety of factors, including the gap between the transmitter and the chip controller or display, whether there is "noise" or other electronic disturbance signal, can you demand Reducer, reducer status, etc. The most economical and useful approach to transmitters with mA inputs for many OEM devices with short inter-controller and controller spacing.
If the demand narrows the input signal, the best picker has a built-in reduced transmitter. The mA level input or frequency input is best used for long interval transmission or for strong electronic disturbance signals.
In addition to the need to select mA or frequency input in an environment with high RFI or EMI targets, consider special maintenance or filters.
6, The type of output form determines the choice of excitation voltage
Many transmitters have built-in voltage-conditioning installations, which make them a large supply voltage field. Some transmitters are quantitatively configured and require a stable task voltage. Therefore, the task voltage determines whether a sensor with a conditioner can be used. When selecting a transmitter, it is necessary to comprehensively consider the task voltage and the cost.
7. After the transmitter times out the task, the demand adheres to the stability.
Most of the transmitters will “drift” after experiencing excess tasks, so it is necessary to understand the stability of the transmitter before purchase. This after-the-fact task can increase the troubles that will be displayed in future applications.
8. Do you need an interchangeable transmitter?
Determine if the required transmitter can accommodate multiple operating systems. This is generally important, especially for OEM products. Once the product is delivered to the customer, the cost of the customer's calibration is considerable. If the product is interchangeable, even changing the transmitter used will not affect the overall system.
9. What is the connection between the transmitter and other electronic devices?
Can you demand a short interval? If a long interval is used, can you use an adapter?
10, The transmitter packaging problem
The package of the transmitter is often negligently neglected by its frame, but this will gradually reveal its defects in later applications. When purchasing a transmitter, you must think about the task environment of the future transmitter, how to humidity, how to install the transmitter, whether there will be intense impact or vibration.
In the production innovation of industrial instruments, in consideration of the actual production needs, it is necessary to pay attention to professional standards with practical functions and high precision. As a special instrument product with practical functions, pressure transmitter can transmit pressure information in different environments in a timely manner, which can bring better choice and design to production, and guarantee good product quality. In terms of brand-based production, Huaheng Instrument has become an industry-specific instrument that meets the needs of practical applications.