Gauge diaphragm material, urgent!

I did some research and found that they are generally made of copper alloys, stainless steel, or special materials. Take a quick look; I don’t really understand it either

Definition of pressure: The concept of pressure here actually refers to the physical quantity of pressure, that is, the amount of force per unit area. Absolute pressure: Pressure measured with respect to the absolute pressure zero point, being higher than that zero point. Positive pressure: Pressure that is higher than atmospheric pressure, measured with atmospheric pressure as the reference. Negative pressure (vacuum): A pressure that is below atmospheric pressure, measured with atmospheric pressure as the reference. Differential pressure: The difference between two pressures. Gauge pressure: Pressure that is greater than or less than atmospheric pressure, measured with atmospheric pressure as a reference. Gauge: A device that uses atmospheric pressure as a reference to measure pressures that are either lower or higher than atmospheric pressure. Vacuum level – Method of expressing pressure and its classification. There are two ways to express pressure: one is the pressure expressed with absolute vacuum as a reference, which is called absolute pressure ； Another type is the pressure expressed relative to atmospheric pressure, known as gauge pressure. Since the pressure measured by most pressure gauges is relative pressure, relative pressure is also known as gauge pressure. When the absolute pressure is less than atmospheric pressure, it can be expressed as a value that is less than one atmosphere of absolute pressure within the container. It is called “vacuum level”. Their relationship is as follows: Absolute pressure = Atmospheric pressure + Relative pressure. Vacuum degree = Atmospheric pressure – Absolute pressure. The legal unit of pressure in China is Pa (N/㎡), known as Pascal, abbreviated as Pa. Due to the extremely small scale of this unit, its 106 times larger unit, MPa (megapascals), is commonly used. Applications of pressure gauges: In industrial process control and technical measurement, mechanical pressure gauges are increasingly widely used because their elastic sensing elements possess high mechanical strength and are easy to manufacture. 　　The elastic sensing element in a mechanical pressure gauge undergoes elastic deformation as pressure changes. Mechanical pressure gauges use sensitive elements such as Bourdon tubes, diaphragms, bellows, and corrugated tubes, and are classified accordingly. The measured pressure is generally considered a relative pressure. Generally, atmospheric pressure is selected as the reference point. The elastic deformation of the elastic element under the action of medium pressure is amplified through the gear transmission mechanism of the pressure gauge, causing the gauge to display a relative value (higher or lower) with respect to atmospheric pressure. 　　The pressure values within the measurement range are displayed by a pointer, and the indication range of the dial is typically set at 270 degrees. Classification of pressure gauges: Pressure gauges can be divided into precision pressure gauges and general-purpose pressure gauges based on their measurement accuracy. The measurement accuracy grades of precision pressure gauges are 0.1, 0.16, 0.25, and 0.4 respectively ； The measurement accuracy grades of general pressure gauges are 1.0, 1.6, 2.5, and 4.0 respectively. Gauge pressure meters are classified into general gauge pressure meters, absolute pressure meters, and differential pressure meters, depending on the reference for the pressure they indicate. Ordinary pressure gauges are based on atmospheric pressure ； The gauge pressure meter is based on the absolute pressure zero point ； A differential pressure gauge measures the difference between two pressures being measured. 　　Based on their measurement range, pressure gauges are classified into vacuum gauges, pressure-vacuum gauges, micro-pressure gauges, low-pressure gauges, medium-pressure gauges, and high-pressure gauges. Vacuum gauges are used to measure pressure levels below atmospheric pressure ； Pressure vacuum gauges are used to measure pressure values that are lower than or higher than atmospheric pressure ； Micromanometers are used to measure pressure values below 60,000 Pa ； The low-pressure gauge is used to measure pressure values from 0 to 6 MPa ； Medium-pressure gauges are used to measure pressure values ranging from 10 to 60 MPa ； High-pressure gauges are used to measure pressure values above 100 MPa. 　　The casing of the seismic pressure gauge is designed as a fully sealed structure, and it is filled with damping oil; thanks to its damping effect, it can be used in environments where there is vibration or fluctuations in medium pressure (load). 　　A pressure gauge equipped with an electric contact control switch can perform signaling and alarm functions or control functions. 　　Gauge pressure transmitters with remote transmission mechanisms can provide the electrical signals required in industrial engineering (such as resistance signals or standard direct current signals). 　　The isolator (chemical seal) used on diaphragm gauges enables the separation of the medium to be measured from the instrument through the diaphragm, allowing for the measurement of pressure in highly corrosive, high-temperature, or crystallizing media. 　　The elastic element of a pressure gauge: In mechanical pressure gauges, the elastic sensing element undergoes elastic deformation as pressure changes. Mechanical pressure gauges use sensitive elements such as Bourdon tubes, diaphragms, bellows, and corrugated tubes, and are classified accordingly. Sensitive elements are generally made of copper alloys, stainless steel, or special materials. Elastic sensitive elements: ?? ?? Bourdon tubes are classified into types such as C-type tubes, coiled spring tubes, and spiral tubes. Cold-work hardenable material billets are generally used; they possess high plasticity in their annealed state, and after pressure processing, cold working, and heat treatment, they acquire high elasticity and strength. Under the action of pressure in the internal cavity, the Bourdon tube utilizes its elastic properties to conveniently convert pressure into an elastic displacement at its free end. The measurement range of a Bourdon tube is generally from 0.1 MPa to 250 MPa. ?? The diaphragm sensor element is a circular diaphragm with wavy patterns; it is located between two flanges, either welded to the flanges or with its edges sandwiched between them. One side of the diaphragm is under the pressure of the medium being measured. The slight bending deformation generated by such a diaphragm can be used to indirectly measure the pressure of the medium. The level of pressure is indicated by the pointer. The diaphragm transmits greater force compared to a Bourdon tube. Since the periphery of the diaphragm itself is fixed, it has good vibration resistance. Diaphragm pressure gauges can provide high levels of overpressure protection (for example, with the diaphragm attached to the upper flange). A protective coating can also be applied to the diaphragm to improve corrosion resistance. Diaphragm pressure gauges can be used to measure media with very high viscosity, that are dirty, or crystalline, by employing measures such as open flanges, flushing, and openings. The pressure measurement range of diaphragm pressure gauges is 1600 Pa to 2.5 MPa. ?? The diaphragm sensor element consists of two diaphragms with a circular wave-shaped cross-section that are fitted together. The pressure of the medium is applied to the inner side of the diaphragm chamber, and the deformation resulting therefrom can be used to indirectly measure the pressure of the medium. The magnitude of the pressure value is displayed by the pointer. Diaphragm pressure gauges are generally used to measure low pressures of gases, and they possess a certain degree of overpressure protection capability. When several diaphragm sensor elements are stacked together, they generate a large transmission force to measure extremely small pressures. The pressure measurement range of the diaphragm gauge is 250 Pa to 60,000 Pa. Structure and working principle of pressure gauges. An open-type Bourdon tube pressure gauge (as shown in Figure 8–2) consists of five main components: the gauge case, the pointer, the dial, the spring-loaded tube, and the transmission mechanism as well as the pipe connections. When pressure from the medium acts on the inside of the Bourdon tube, its movable end expands outward; this movement is transmitted through the transmission mechanism to rotate the pointer, thereby indicating the pressure of the medium on the dial. 1. Case 2. Bourdon tube 3. Pointer 4. Movement 5. Link 6. Dial 7. Joint Figure 8-2: Structural diagram of a pressure gauge. A hermetically sealed spring pressure gauge is also composed of six main parts: the casing, pointer, dial, Bourdon tube, elbow, and transmission mechanism. The interior cavity of the Bourdon tube is sealed; external pressure acts on the outside of this tube, causing it to deform, and the transmission mechanism then drives the pointer to rotate, thereby indicating the ambient pressure. The number inside the circle below the pressure gauge dial indicates the accuracy class of the gauge. It indicates that the basic error of this gauge does not exceed a certain percentage of the full scale. The smaller the number, the higher the precision. Principles for selecting pressure gauges: The full-scale scale of the pressure gauge should be 1.5–3.0 times the maximum operating pressure of the container or container system; it is preferable to use a scale that corresponds to 2 times that value. The diameter of the pressure gauge dial should be no less than 100 mm, and it is advisable to have a red scale on the dial indicating the maximum operating pressure of the container system. Installation settings for pressure gauges: (1) They should be placed in locations where they can be easily observed and cleaned, and should be protected from adverse factors such as radiant heat, freezing, or vibration ； (2) The pressure gauge should be installed vertically; if it is installed at a higher position, it may be tilted slightly forward for easier viewing, but the tilt angle must not exceed 30 degrees ； (3) In one case, a buffer elbow should be installed in front of the pressure gauge to prevent compressed air from rushing directly into the spring elbow, and it can also store condensed water ； (4) A three-way stopcock or needle valve should be installed between the pressure gauge and the buffer elbow to facilitate the replacement and calibration of the pressure gauge. 4. Requirements for the use of pressure gauges: Before installation, pressure gauges must be calibrated by an **approved metrology department, which shall issue a calibration certificate confirming compliance. The pressure gauge in use should be calibrated at least once a year. It must be replaced immediately if any of the following problems occur: inaccurate pressure indication, a loose pointer, unclear markings, broken dial glass, a pointer that does not return to zero after pressure release, or damaged seals. Methods for adjusting pressure gauge readings that are out of range. Single-coil Bourdon tube pressure gauges are widely used as pressure measuring instruments in industry. During calibration, it is common for the indicated values to be out of range; the specific adjustment methods are as follows: 1. The amount by which each calibration point is out of range is the same. After boosting the voltage, the pointer can be reinstalled at the first measurement point other than the zero point to calibrate the indicated value. 　　2? The difference exhibits linear error. As the error gradually increases, move the indication adjustment screw outward to increase the arm length ； Conversely, it moves inward, reducing the arm length. 　　3? The indication deviates first rapidly (positive error) and then slowly (negative error). Turn the movement counterclockwise to increase the angle between the pull rod and the sector gear ； Conversely, turn the movement clockwise to reduce the angle. After adjustment. The error is of a linear nature; simply adjust the indication screw to correct it. 　　4? The indicated value is out of tolerance around half of the pressure. After boosting the voltage, the pointer can be reinstalled in the middle position; if the error cannot be eliminated, the angle between the tie rod and the sector gear should be adjusted for comprehensive correction. 　　5? Only one or two points are out of tolerance. Check the fit of the movement in the vicinity of that point; when there is a positive clearance, there is dirt or burrs at the gear meshing areas ； When the deflection is negative, the teeth are worn and damaged, and should be repaired or replaced. 　　6? If a pressure gauge is adjusted multiple times yet the deviation remains excessive and the pointer does not return to zero, it may be due to deformation of the spring tube, which requires replacement. 　　After the adjustment is complete, assemble all the components of the instrument and conduct another calibration in accordance with the calibration procedures. There are three connection methods for the spring tube connections: Soldering…used for connecting copper materials; Silver-copper soldering…used for connecting copper materials with stainless steel; TIG welding…used for connecting stainless steel components together. The selection and pricing of pressure gauges depend on the customer’s requirements; the type of pressure gauge is determined first, and then the appropriate model is chosen based on the installation environment. 1 Indoor: A□□□; 2 Outdoor: B□□□; 3 Vibration-prone environments: GV□□; 4 High-pressure and explosion-proof environments: CD□□. 5 Installation methods for pressure gauges: Radial, radial wall-mounted (with panel); Axial, axial mounting fixtures, axial panels. 6 Selection of scale markings on the pressure gauge dial. 7 Pressure gauges with flanged diaphragms or capillaries: Direct-type, remote-transmission type. Used in: power plants, oil industries, chemical plants, etc. 8 Attachments: siphons, throttle valves, dampers, overpressure protectors, connectors 9 Oil and water prohibited; when measuring oxygen, indicate “oil-free treatment”; when measuring acetylene, indicate “oil-free treatment” as well as corrosion resistance ； When measuring hydrogen, please indicate “Oil and water treatment prohibited”. Common units of pressure conversion table: Pascal Pa (N/m2), Kilogram-force per square centimeter Kgf/cm2, Bar, Millibar mbar, Standard atmospheric pressure atm, Torr, Inches of water column inH2O, Millimeters of mercury mmHg, Pounds per square inch PSI (lb/in2). The conversions are as follows: Pa – 1, 1.02×10-5, 1×10-5, 0.01, 9.87×10-6, 7.5×10-3, 4.01×10-3, 7.5×10-3, 1.45×10-4; Kgf/cm2 – 9.8×104, 1, 0.98, 980.67, 0.967, 735.56, 393, 735.56, 14.2; Bar – 1×105, 1.02, 1, 1000, 0.987, 750.06, 401, 750.06, 14.5; Millibar – 100, 1.02×10-3, 0.001, 1, 9.87×10-4, 0.75, 0.401, 0.75, 1.45×10-2; Atmosphere – 101325, 1.03, 1.01, 1013.25, 1, 760, 406, 760, 14.7; Torr – 133.32, 1.36×10-3, 1.33×10-3, 1.33, 1.32×10-3, 1, 0.535, 1, 1.93×10-2; Inches of water column – 249.09, 2.54×10-3, 2.49×10-3, 2.49, 2.46×10-3, 1.87, 1, 1.87; Millimeters of mercury – 133.32, 1.36×10-3, 1.33×10-3, 1.33, 1.32×10-3, 1, 0.535, 1, 1.93×10-2; PSI – 6895, 7.03×10-2, 6.90×10-2, 68.95, 6.81×10-2, 51.715, 27.6, 51.715, 1. For easier memorization, the following rules can be used: 1. 1 atm = 0.1 MPa = 100 KPa = 1 kilogram = 1 bar = 10 meters of water column = 14.5 PSI. 2. 1 KPa = 0.01 kilogram = 0.01 bar = 10 mbar = 7.5 mmHg = 0.3 inHg = 7.5 torr = 100 mmH2O = 4 inH2O

Tantalum is a good choice for metal materials, or PTFE can be used as a lining

Titanium material – a good material for corrosion resistance