Classification and introduction of pressure transmitters Gauge pressure transmitter:
Gauge pressure transmitters are pressure transmitters with local atmospheric pressure as the reference zero.
2. Absolute pressure transmitter:
是以真空度为参考零点的一款压力变送器。 Absolute pressure transmitter is a pressure transmitter with vacuum as the reference zero. During use, the reference zero point of the sensor can be adjusted automatically with the change of location and area without correction. The appearance is the same as the gauge pressure transmitter.
3． Differential pressure transmitter:
The differential pressure transmitter is a pressure transmitter that measures the pressure difference between the two pressure chambers. The differential pressure transmitter has two pressure chambers, "+" and "-". It accepts two pressures as comparison values, and usually uses the larger end as the "+" pressure cavity.
4． Input / plug-in level transmitter:
The level transmitter is divided into two types: input type and plug-in type. The two forms are the same, and both convert the pressure to the liquid depth. When the water depth is 1m, the pressure on the transmitter is 10KPa, pay attention when ordering such sensors:
1. The measured liquid density shall be notified to the production unit.
2. The production unit shall be notified when the measuring medium is corrosive.
3． The production unit is notified when the temperature of the measuring medium exceeds -10 ° C and 60 ° C.
5. Medium and high temperature pressure transmitter:
In order to measure the ambient temperature of the field is too high or the temperature of the measuring medium is too high, a medium-high temperature pressure transmitter must be used. The transmitter has a good zero temperature coefficient and sensitivity temperature coefficient, which can ensure measurement accuracy in high temperature environments. . When ordering this type of transmitter, you must inform the temperature of the measurement medium and the ambient temperature in order to facilitate the producer to respond reasonably.
是专业用于真空测量控制的新系列产品，完全解决了真空测量难的问题，广泛应用制药，医疗设备，航空航天，科研，检漏，自动化设备配套等领域。 Absolute pressure transmitter, also known as absolute pressure transmitter, is a new series of products specialized in vacuum measurement and control, which completely solves the difficult problem of vacuum measurement. It is widely used in pharmaceutical, medical equipment, aerospace, scientific research, leak detection, and automation equipment. Supporting areas.
Features: ● High accuracy
● Continuously adjustable external range and zero
● Good stability
● Up to 500% of positive migration and 600% of negative migration
● Second-line system
● Adjustable damping and resistance to over-voltage
● Solid sensor design
● No mechanical moving parts, less maintenance
● Light weight (2.4kg)
● Full series of unified structure and strong interchangeability
● Miniaturization (166mm total height)
● Optional diaphragm material
● Unilateral anti-overpressure
● Low-pressure cast aluminum alloy shell
● Super measurement performance for pressure, differential pressure, liquid level, flow measurement
● Digital accuracy: + (-) 0.05%
● Simulation accuracy: + (-) 0.75% + (-) 0.1% FS
● Full performance: + (-) 0.25FS
● Stability: 0.25% for 60 months
● Range ratio: 100: 1
● Measurement rate: 0.2S
● Miniaturized (2.4kg) all stainless steel flange, easy to install
● The process connection is compatible with other products to achieve the best measurement
● The only sensor (patented technology) with H alloy sheath in the world, which achieves excellent cold and heat stability
● Smart transmitter with 16-bit computer
● Standard 4-20mA, with digital signal based on HART protocol, remote control
● Support for upgrading to fieldbus and field control-based technologies. Performance specifications
被测介质的两种压力通入高、低两压力室，作用在δ元件（即敏感元件）的两侧隔离膜片上，通过隔离片和元件内的填充液传送到测量膜片两侧。 Absolute pressure transmitter The two pressures of the measured medium are passed into the high and low pressure chambers, acting on the isolation diaphragms on both sides of the delta element (that is, the sensitive element), and transmitted to the measurement through the spacer and the filling liquid in the element. Diaphragm sides. The measuring diaphragm and the electrodes on the insulating sheets on both sides constitute a capacitor.
When the pressure on the two sides is inconsistent, the measurement diaphragm is displaced. The displacement is proportional to the pressure difference, so the capacitance on both sides is not the same. Through the oscillation and demodulation links, it is converted into a signal proportional to the pressure. The working principle of pressure transmitters and absolute pressure transmitters is the same as that of differential pressure transmitters, except that the pressure in the low-pressure chamber is atmospheric or vacuum.
The A / D converter converts the current of the demodulator into a digital signal, and its value is used by the microprocessor to determine the input pressure value. The microprocessor controls the operation of the transmitter. In addition, it performs sensor linearization. Reset the measurement range. Engineering unit conversion, damping, square root, sensor fine-tuning, and diagnostics and digital communications.
This microprocessor has 16 bytes of program RAM and three 16-bit counters, one of which performs A / D conversion.
The D / A converter fine-tunes the data from the microprocessor and the corrected digital signal. These data can be modified by the transmitter software. The data is stored in the EEPROM, and it is stored intact even if the power is off.
The digital communication line provides the transmitter with a connection interface to external devices (such as a Model 275 intelligent communicator or a control system using the HART protocol). This line detects the digital signal superimposed on the 4-20mA signal and transmits the required information through the loop. Communication type is frequency shift keying FSK technology and according to BeII202 standard
The 1151 GP pressure transmitter provided by the Shanghai Automation Instrument Co., Ltd. marketing center to our customers has a very rich variety, which can accurately measure micro differential pressure to large differential pressure, low pressure to high pressure, liquid level, vacuum degree and specific gravity . With the throttling device, the flow can also be measured without using a square.
Flange type liquid level transmitter with flat flange and plug-in flange; mounting flanges include 4 #, 4 #, 150 # (working pressure is 1.89Mpa) and 300 # (working pressure is 4.95Mpa). Combinations are available for users to choose from. Wetted materials in addition to 316 stainless steel, Hastelloy, Monel and tantalum can be used in corrosive media.
The metal-sealed delta chamber is used as the sensing element, so that the transmitter eliminates the problems of resistance to shock and vibration when transmitting force mechanically; it eliminates errors caused by external stress and torque, and ensures that the transmitter has high stability performance. Reduce the error caused by static pressure (13.79Mpa ～ 31.0Mpa); because each species uses a delta chamber with approximately the same external dimensions, the entire 1151 series has measured from the differential pressure type of 0.12Mpa to the pressure type of 41.37Mpa. Has roughly the same shape and weight.
The Model 1151 transmitter has a compact design and is explosion-proof and weatherproof. Installation, use and adjustment are easy and simple. Terminals and amplifier circuits are placed in the upper, hermetically sealed electrical chamber and are separated from each other. So when field wiring, the amplifier is still working in a sealed state. The amplification circuit has reverse polarity protection to prevent damage to the transmitter due to incorrect connection. The volume change of the 1151 during operation is less than 0.16 ml, which can prevent the liquid column of the measured medium from changing too much, so it is not necessary to add a condenser or a liquid level tube to compensate for the volume change. Anti-corrosive materials such as tantalum, Hastelloy and Monel alloy are used to adapt to the measurement of corrosive media. The use of integrated circuit components and plug-in printed circuit boards results in fewer failures, convenient maintenance, reduced spare parts and maintenance costs.