Pressure gauge and control valve of Shanghai automation instrumentation Co., Ltd.
90 years of hard work, 90 years of hard work. Shanghai Automation Instrument Co., Ltd. (referred to as “Shanghai ziyi”), which completed the asset restructuring and undertaken all the assets (including qualifications), liabilities, business and personnel of Shanghai Automation Instrument Co., Ltd., soon ushered in the 90th anniversary.
90 years is a period of glory and a glorious history. Shanghai ziyi experienced the tide of reform, the wind and the rain, the tides and the tides, from a seedling to today's towering trees, became the backbone of the national automation instrument industry.
Review the 90 years of Shanghai self-instrument. Before and after the founding of New China at the beginning of the last century, Shanghai's self-owned enterprises started from the workshop-style factory, producing the first generation of electric meters, pyrometers, thermocouples, power factor meters, road code meters, pressure gauges, thermometers, Measuring instruments, flow meters, etc., formed the prototype of the Chinese instrument industry.
In the 1970s, Shanghai's self-owned enterprises continued to work hard to produce all kinds of instruments and meters that represent the advanced level at that time, and became the leader in the production of Chinese instruments. At the same time, Shanghai Self-Improvement has produced a large number of instrument products for the development of national defense construction, and has made tremendous contributions. It has been commended and rewarded by the central, local and relevant departments.
In the 1980s and early 1990s, Shanghai Ziyi introduced 24 product technologies from developed countries such as the United States, Japan, Britain, Germany and France, which enabled the main products to be upgraded in terms of variety, quality and technical grade. The overall technology has reached the level of the international 70s。
Entering the 21st century, Shanghai ziyi is a two-level development system headed by a national-level enterprise technology center, stepping up product innovation and improvement, and continues to maintain its leading position in China. A total of more than 60 national standards and industry standards have been completed; a total of 71 projects have been completed, such as the “National Ministry of Science and Technology Major Projects, the National Economic and Trade Commission Major Technology Equipment Localization Innovation Project, and the National Development and Reform Commission Major Technical Reform Project”; 228 national patents.
At present, Shanghai Self-Equipped with the internationally advanced instrument control products and technologies, has formed a self-contained closed-loop product group of Shanghai self-instrument control system, instrumentation and actuators, providing users with the ability and business of automation solutions. Features; relying on powerful and well-equipped product clusters and categories, it can provide complete instrument control and complete sets of services for users in industrial processes and other fields, to meet the different needs of users from field instruments to solutions.
In the face of the ever-changing market, Shanghai Ziyi will unremittingly strive to build the strongest manufacturer of instrument control products in China, and continue to struggle with the development of China's automated instrument industry. We will always keep in mind social responsibility, help low-carbon economy as the yardstick, carefully build green manufacturing, actively participate in public utilities, strive to achieve development with customers, grow together with employees, and make progress with society, and provide customers with advanced technology. Value-added products and services make new contributions to the development of China's instrumentation industry.
Pressure gauges are instruments that use elastic components as sensitive components to measure and indicate above ambient pressure. Applications are extremely common and are found in virtually all industrial processes and research areas. In the field of heat pipe network, oil and gas transmission, water supply and gas supply system, vehicle maintenance and repair shop, etc. can be seen everywhere. Especially in the process of industrial process control and technical measurement, mechanical pressure gauges are more and more widely used due to the high mechanical strength and convenient production of elastic sensitive components of mechanical pressure gauges.
Working principle: The pressure gauge passes through the elastic deformation of the sensitive components (Bourdon tube, bellows, bellows) in the watch, and then the pressure deformation is transmitted to the pointer by the conversion mechanism of the movement inside the watch, causing the pointer to rotate to display the pressure.
Main structure: overflow hole: If an emergency occurs in the Bourdon tube burst, the internal pressure will be released to the outside through the overflow hole to prevent the glass panel from bursting. Note: In order to maintain the normal performance of the overflow hole, it is necessary to leave at least 10mm space behind the table, and the overflow hole cannot be modified or plugged.
Pointer: In addition to the standard pointer, other pointers are also optional.
Glass panel: In addition to standard glass, other special materials such as tempered glass and non-reflective glass are also available.
Performance classification: normal type (standard), ordinary type (M) for steam, heat-resistant type (H), vibration-resistant type (V), vibration-resistant type (MV) for steam, heat-resistant type (HV).
Treatment: Oil-free/water-free treatment Remove water or oil remaining in the wetted parts during manufacture.
Exterior designation: The color of the housing must be specified in addition to the standard color.
Throttle (optional): To reduce the pulsation pressure, the throttle is installed at the pressure inlet.
Note: 1. The meter must be vertical: it should be tightened with a 17mm wrench when installing.
Do not twist the case strongly; avoid collision when transporting;
2, the instrument should be used in the ambient temperature of -25 ~ 55 ° C;
3, using the working environment vibration frequency <25HZ, the amplitude is not more than 1mm;
4. In use, because the ambient temperature is too high, the instrument indication value does not return to zero or the indication value is out of tolerance. The sealing rubber plug on the upper part of the case can be cut open to make the inner cavity of the instrument pass through the atmosphere;
5. The scope of use of the instrument should be between 1/3 and 2/3 of the upper limit;
6. Isolation devices should be added to the corrosive medium, the medium that may crystallize, and the medium with higher viscosity;
7. The instrument should be checked frequently (at least once every three months), and repaired if it is found to be faulty;
8. The instrument shall be repaired or replaced by the company if it is found to be ineffective or damaged due to poor manufacturing quality within half a year from the date of leaving the factory;
9. Instruments that measure corrosive media are required, and the requirements should be indicated when ordering.
The selection of the pressure gauge should be based on the production requirements of the process and specific analysis for the specific situation. Under the premise of meeting the requirements of the process, it should be considered comprehensively and comprehensively in accordance with the principle of economy. Generally, the following aspects should be considered:
1, the choice of type
The type of instrument must be selected to meet the requirements of process production. For example, is it necessary to remotely transmit, automatically record or alarm; whether the nature of the measured medium (such as the temperature of the measured medium, the viscosity, the corrosiveness, the degree of contamination, whether it is flammable or explosive, etc.) imposes special requirements on the instrument. Environmental conditions (such as humidity, temperature, magnetic field strength, vibration, etc.) requirements for the type of instrument. Therefore, the correct selection of the instrument type according to the process requirements is an important prerequisite for ensuring the normal operation and safe production of the instrument.
For example, spring tubes of ordinary pressure gauges are mostly made of copper alloy (high-pressure alloy steel), while materials for ammonia pressure gauge spring tubes are made of carbon steel (or stainless steel), and copper alloy is not allowed. Because ammonia reacts with copper and can explode, ordinary pressure gauges cannot be used for ammonia pressure measurement.
Oxygen pressure gauges and ordinary pressure gauges can be identical in structure and material, except that oxygen pressure gauges must be banned. Because the oil enters the human oxygen system, it is easy to cause an explosion. When using the oxygen pressure gauge, it is not possible to use oil as the working medium like the ordinary pressure gauge, and the oxygen pressure gauge should strictly avoid contact with oil during storage. If it is necessary to measure the oxygen pressure with an existing oil pressure gauge, it must be repeatedly cleaned with carbon tetrachloride before use, and carefully checked until there is no oil.
2. Determination of measurement range
In order to ensure that the elastic element can work reliably within the safe range of elastic deformation, when selecting the gauge range, it is necessary to leave sufficient space according to the magnitude of the measured pressure and the pressure change. Therefore, the upper limit of the pressure gauge It should be higher than the maximum possible pressure value in the process. According to the "Technical Regulations for Chemical Self-Control Design", when measuring stable pressure, the maximum working pressure should not exceed 2/3 of the upper limit of measurement; when measuring the pulsating pressure, the maximum working pressure should not exceed 1/2 of the upper limit of measurement; When measuring high pressure, the maximum working pressure should not exceed 3/5 of the upper limit of measurement. Generally, the minimum value of the measured pressure should not be less than 1/3 of the upper limit of the meter measurement. Thereby ensuring the linear relationship between the output of the meter and the input
After calculating the upper and lower limits of the meter according to the maximum and minimum values of the measured parameters, this value cannot be directly used as the measuring range of the meter. When selecting the upper limit of the scale of the instrument, we should select it in the standard series specified by the state. China's pressure gauge measurement range standard series are: -0.1-0.06, 0.15; 0-1, 1.6, 2.5, 4, 6, 10X10" MPa (where n is a natural integer. It can be positive or negative).
3. Selection of accuracy level
According to the maximum absolute error allowed by the process production and the selected instrument maximum range, calculate the maximum reference error allowed by the instrument, and determine the accuracy of the instrument in the accuracy level specified by the state. In general, the more precise the instrument selected, the more accurate and reliable the measurement. However, it cannot be considered that the higher the accuracy of the selected instrument, the better, because the more sophisticated the instrument is generally more expensive, the more troublesome operation and maintenance.
1. For measuring special media such as viscosity or acid and alkali, diaphragm pressure gauge and stainless steel should be used.
Spring tube, stainless steel movement, stainless steel housing or bakelite housing.
According to the different mediums tested, there should be a specified color code on the pressure gauge, and the name of the special medium should be indicated. The oxygen meter must be marked with the words "oil-free" in red, the dark green color line in hydrogen, and the ammonia. Yellow horizontal line color code and so on.
When installing against the wall, a pressure gauge with an edge should be used; when directly installed on the pipeline, a pressure gauge without edge should be used; when directly measuring the gas, a pressure gauge with a safety hole behind the case should be used. For the position of the pressure measurement and for the convenience of observation management, the diameter of the case should be selected.
There are many types of pressure gauges, not only general (ordinary) pointer indication type, but also digital type; not only conventional type, but also special type; not only contact type, but also long-distance type; not only vibration-resistant type, but also earthquake-resistant Type; not only the diaphragm type, but also the corrosion resistance type. The pressure gauge series is complete. It not only has a regular series, but also a digital series; not only the general media application series, but also the special media application series; not only the switching signal series, but also the remote signal series, etc., all of which originate from practical needs, have formed Complete series. The specifications and models of the pressure gauge are complete and the structure is perfect. From the nominal diameter, there are Φ40mm, Φ50mm, Φ60mm, Φ75mm, Φ100mm, Φ150mm, Φ200mm, Φ250mm and so on. Seen from the installation structure type, there are direct mounting type, embedded type and convex type, wherein the embedded type is divided into radial embedded type and axial embedded type, and convex type also has radial convex type and axial direction. Convex type. Directly mounted, it is divided into radial direct mounting and axial direct mounting. Among them, the radial direct installation type is a basic installation type, and generally refers to a radial direct installation type when the installation structure type is not specified. The axial direct mounting type considers the stability of its own support and is generally only used on pressure gauges with a nominal diameter of less than 150 mm. The so-called embedded and convex pressure gauges are the belt side (mounting ring) pressure gauges we often say. The axially embedded type has both the axial front band edge and the radial insert type, which means the radial front band edge and the radial convex type (also called wall type) refers to the radial rear band edge pressure gauge. Seen from the volume and range sections, the positive pressure range is divided into a micro-pressure range section, a low-pressure range section, a medium-pressure range section, a high-pressure range section, and an ultra-high-pressure range section, each of which is within each range section. It also subdivides several measurement ranges (meter range); there are three kinds of negative pressure (vacuum gauge) in the negative pressure range (vacuum); the positive pressure and negative pressure combined pressure gauge is a cross-domain pressure table. Its specification name is pressure vacuum gauge, also known as vacuum pressure gauge. It can measure not only positive pressure but also negative pressure. The classification of the accuracy of the pressure gauge is very clear. Common accuracy levels are 4, 2.5, 1.6, 1, 0.4, 0.25, 0.16, 0.1, and so on. The accuracy level should generally be marked on its dial, and its logo is also specified. For example, “1” indicates that its accuracy level is level 1. For some pressure gauges with very low precision grades, such as those under Class 4, there are some that do not need to measure the exact pressure value. Only the pressure range is indicated. For example, the pressure gauge on the fire extinguisher can not mark the accuracy grade. .
Pressure gauge according to its measurement accuracy: can be divided into precision pressure gauges, general pressure gauges. The precision of the precision pressure gauges is 0.1, 0.16, 0.25, and 0.4, respectively. The accuracy of the general pressure gauges is 1.0, 1.6, 2.5, and 4. 0.
The pressure gauge is based on its measurement standard: the pressure gauge is different according to the reference pressure.
Divided into general pressure gauge, absolute pressure gauge stainless steel pressure gauge, differential pressure gauge. The general pressure gauge is based on atmospheric pressure; the absolute pressure gauge is based on the absolute pressure zero; the differential pressure gauge measures the difference between the two measured pressures.
The pressure gauge according to its measurement range: divided into vacuum gauge, pressure vacuum gauge, micro pressure gauge, low pressure gauge, medium pressure gauge and high pressure gauge. The vacuum gauge is used to measure the pressure value less than atmospheric pressure; the pressure vacuum gauge is used to measure the pressure value less than and greater than the atmospheric pressure; the micro pressure gauge is used to measure the pressure value less than 60000 Pa; the low pressure gauge is used to measure the pressure value of 0-6 MPa Medium pressure gauge is used to measure the pressure value of 10~60MPa;
The pressure gauge is displayed according to its mode: it is divided into a pointer pressure gauge and a digital pressure gauge.
The pressure gauge is divided according to its function: the pressure gauge can be divided into the local indication type pressure gauge and the charged signal control type pressure gauge according to the different functions of the pressure gauge.
General pressure gauges, vacuum pressure gauges, shock-resistant pressure gauges, stainless steel pressure gauges, etc. all belong to the local indication type pressure gauge, and there is no other control function except the indicated pressure.
The output signals of the charged signal control type pressure gauge mainly include:
1, switching signals (such as electrical contact pressure gauge)
2, resistance signal (such as resistance remote pressure gauge)
3, current signal (such as inductive pressure transmitter, remote pressure gauge, pressure transmitter, etc.)
The pressure gauge can be divided into: according to the characteristics of the measured medium:
1. General pressure gauge: The general pressure gauge is used to measure the pressure of liquid, gas or steam which has no corrosive effect on copper and copper alloy without explosion, no crystallization or solidification;
2, corrosion-resistant pressure gauge: corrosion-resistant pressure gauge is used to measure the pressure of corrosive medium, commonly used stainless steel pressure gauge, diaphragm pressure gauge, etc.;
3, explosion-proof pressure gauge: Explosion-proof pressure gauges are used in hazardous areas with explosive mixtures in the environment, such as explosion-proof electrical contact pressure gauges, explosion-proof transmitters, etc.
4. Special pressure gauges.
According to the use of pressure gauge: can be divided into ordinary pressure gauge, ammonia pressure gauge, oxygen pressure gauge, electric contact pressure gauge, remote pressure gauge, vibration pressure gauge, pressure gauge with inspection pointer, double needle double tube or double needle single Pipe pressure gauge, digital pressure gauge, digital precision pressure gauge, etc.