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1 Instructions and Uniform Provisions 1.1 International System of Units The units of the International System of Units (denoted as SI) consist of 7 base units, 2 auxiliary units, and numerous derived units. The International System of Units, SI, consists of SI units, SI prefixes (16 in total, from 10-18 to 1018), and decimal multiples and fractional parts of SI units. The SI unit is not an abbreviation for International System of Units units; it is a phrase with a specific meaning. In addition to SI units, the units of the International System of Units should also include their multiples and fractional units. דThe measurement units are in accordance with the International System of Units (SI standards), and the basic units are as follows: “……%, ppm, 4–20 mADC……”. The concepts of “SI standards” and “basic units” are incorrect; %, ppm, and 4–20 mADC are not units at all. 1.2 References to standards and regulations in design documents are subject to time and scope limitations. Cited documents are not subject to the revisions and updates of the standards and regulations they cite after the deadline. It’s not the latest version that is effective. “The provisions in the following documents become provisions of these regulations through reference to them. For any referenced document dated, all subsequent amendment sheets (excluding corrections) or revised versions shall not be applicable to these provisions. For reference documents without a date, the latest version (including all amendment sheets) applies to these regulations. ” In design documents, institutional logos are generally not included. In certain special projects, the methods specified by the project are adopted. 1.3 ISO9000 Standard Certification ISO9000 standard certification is a recognition of a company’s or enterprise’s quality assurance standards and management systems for design, production, installation, and services, rather than a certification of product quality. It should be said that “priority should be given to products manufactured by companies or manufacturers that have obtained certification under the ISO9000 quality management standard.” And it should not be said that “products certified under the ISO9000 standard should be given priority.” 1.4 Composition of the intrinsically safe system The intrinsically safe system is composed of field instruments, safety barriers, and connection wires. In engineering design, attention must also be paid to the power supply and impedance matching of safety barriers with DCS or secondary instruments. These are two different concepts that should not be confused. ×It is incorrect to state that “the selection of safety barriers must match the on-site transmitters and DCS to form an intrinsically safe system”. 1.5 Variables, parameters, and constants: A variable is a quantity that changes depending on the conditions. In mathematics, variables include independent variables and dependent variables; in control engineering, there are control variables and controlled variables. The relationship between variables is called a function or equation. In functions or equations, the coefficients of variables are sometimes referred to as parameters. 1.6 Standard spring specifications for control valves: The applicable air supply pressures for the standard springs of control valves include 20~100 kPa, 40~200 kPa, etc. Those with a gas source pressure specification of 40~200 kPa also use standard springs. Generally speaking, spring specifications that are not listed on the control valve sample or that are specified separately are considered non-standard springs. דTo improve the response speed of the control valve and achieve greater output force, spring ranges other than standard springs (20–100 kPa) can be used. ” There is a grammatical error in this sentence: “Non-standard springs (20–100 kPa)” – the term “other than” makes them standard springs again. 1.7 Correct language × “ESD should be independent of DCS.” The correct phrases are: “ESD should be independent”, “ESD should be separate from DCS”, “ESD should be independent of DCS”. ESD does not necessarily have to be independent of DCS; the so-called \"independent\" setup refers to the separation of the controllers and consoles used in safety systems from the control system itself. Standards such as IEC61508 and IEC61511, as well as the relevant specifications of foreign engineering companies, do not stipulate that DCS equipment cannot be used in safety systems; they only require an evaluation and calculation of the overall safety level. ד“DCS will be selected from world-renowned manufacturers”, “……it is necessary to give full consideration to various aspects such as its operation station, control functions, data acquisition functions, software capabilities, redundancy, system expansion, and system development”, etc. – all of these statements are not clear in meaning. ד“Universal” and “omnidirectional” should be replaced with “multifunctional” and “adjustable”. 2 Regarding differential pressure flowmeters, these include various throttling devices, venturi flowmeters, cone flowmeters, elbow flowmeters, wedge flowmeters, etc. Their measurement principle is based on the continuity equation and Bernoulli’s equation, while the flow coefficient is determined through data processing of experimental data. Standard throttling devices, based on the principles of hydrodynamic similarity and geometric similarity, can achieve the desired measurement accuracy without the need for calibration using actual fluids, as long as they are manufactured and installed according to standards. Throttling devices included in the ISO standards are standard throttling devices, while all others are non-standard throttling devices. Note: Non-standard throttling devices must be calibrated using actual fluids and the flow coefficient adjusted in order to achieve the desired measurement accuracy. “\"1\" Flange-mounted pressure tapping concentric sharp-hole orifice plate\" should be replaced with \"Flange-mounted pressure tapping standard orifice plate\". There are many variations of Pitot tube (Anemometer) flow meters, such as the “Vortex” model, etc.; their measurement principle is the same and there is no essential difference between them, so the prices should not vary significantly. It seems that there are standards for average velocity tube flowmeters, while no standards exist for other modified versions of them; all such devices should be considered non-standard throttling devices. 3 Regarding the explosion protection rating IEC/CENELEC, the explosion protection mark indicates the explosion protection method, environmental zone, category of explosive gases, and the group for the maximum surface temperature of electrical equipment. For example: if the explosion protection mark is EE*aIICT4, it indicates CENELEC certification, intrinsically safe explosion protection, explosive environments other than coal mines (Class II), Group C gas category, and T4 temperature group. In the Americas, explosion-proof markings do not indicate the method of explosion protection; the method of explosion protection should be specified in the instrument specification sheet. For example: FM explosion-proof for Class I, Division I, Groups B, C, and D. It indicates FM certification, flameproof explosion protection type, suitability for explosive gases and vapors (Class I), Zone 1 of explosive environments (continuous presence), with gas groups B, C, and D. The explosion-proof marking of European IEC/CENELEC does not indicate the zone category of the explosive environment. The explosion protection rating for American FM does not include a category for the maximum surface temperature of electrical equipment. It is incorrect if the explosion protection rating is specified as “EE*aIICT4, FM certified”. China’s explosion protection standards are basically consistent with IEC/CENELEC standards. Some standards are adopted equivalently. In the explosion protection standards of the Americas, “Explosion proof” refers to the flameproof type of explosion protection. In European explosion protection standards, the flame-proof type of explosion protection is referred to as Flame Proof; Explosion Proof is an umbrella term for explosion protection, or it can also be called Explosion Protected. 4 Regarding explosion protection: explosion-proof types are not the same as waterproof types. If waterproof performance is desired, it is also necessary to specify the waterproof type and the protection rating. Because many flameproof junction boxes are not waterproof. In the case of intrinsically safe systems, waterproof junction boxes are more practical than flameproof junction boxes. In the case of an intrinsically safe system, the explosion-proof sealing joint at the transmitter’s inlet is unnecessary. 5 On glass level gauges 5.1 Material of glass plate level gauges When 20-grade steel is used for the material of glass plate level gauges, the temperature can reach 470°C, which is sufficient for such gauges; the so-called heat-resistant steel is actually Cr5Mo steel. 5.2 Quartz glass tubes Quartz glass tubes should not be used for measuring the level of liquids under high temperature and pressure conditions, even though the specifications listed are PN10.0MPa, T