Criteria for intact instruments

Methods for calculating statistics on instrument automation equipment: I. Methods for calculating the four rates of conventional instruments; II. Methods for calculating the four rates of process control computer systems along with relevant explanations. I. The four rates for process computers include system utilization rate, hardware integrity rate, failure rate, and software availability rate. The detection units and control functions within a process control computer system are included in the calculations related to the integrity rate, utilization rate, and control rate of conventional instruments. 2. Calculation of computer system utilization rate 3. Calculation of hardware integrity rate and failure rate 4. Calculation of software availability rate Note: A failure refers to a system outage. MTBF – Total fault-free time during the statistical period (hours). MTTR – Total time spent resolving faults during the statistical period (hours). NH – Total number of hardware units. NS – Total number of software units. N – Number of functional units. T – Duration of the statistical period (hours). t – Time required for a single unit to fail (hours). t_i – Actual time during which a single software unit is in use (hours). t_j – Time during which a single software unit is unavailable due to manufacturing issues (hours). III. Methods for counting the number of units in conventional instruments: 1. Number of units: Each independent unit that can form part of a detection or control circuit is counted separately. These include: (1) Control units: various regulators in the control room, various base-type regulators on site, and regulator units of assembled instrument series; if a regulator is integrated with secondary instruments, it is counted as one control instrument. (2) Measurement transmitters: differential pressure transmitters, pressure transmitters, temperature transmitters, color-temperature converters, power transmitters, velocity transmitters, gap transmitters, camera transmitters, millivolt transmitters, level transmitters, strip level gauges, remote-transmission rotameters, oval flow meters, turbine flow meters, vortex flow meters, electromagnetic flow meters, ultrasonic flow meters, load sensors, pre-amplifiers, and various other types of measurement transmitters. (3) Display unit: recorders, indicators, calculators, etc. (4) Calculation units: adders, multipliers and dividers, square root calculators, integrators, relays, proportional setters, arithmetic components of instrument assemblies, digital flow output devices, signal distributors. (5) Auxiliary units: oil-immersed switches, air supply devices, flash alarms, combustible gas detectors, remote control panels, power supply devices for meters, high and low frequency displacement detectors, carriers, relays, electrical isolators, dampers, trip amplifiers, purifiers, high-power heaters, timers, electrical coolers, input and output components for the meter assembly series, hand controllers, flame monitors, multi-point samplers, carburetors, and various types of safety devices, alarm setting devices, high and low value selectors, high-power amplifiers for air currents with interfaces larger than 18 millimeters, etc. (6) Special components: CNC controllers, weighing instruments, shaft displacement vibration meters, tank gauges, industrial cameras, program controllers, separately installed programmers, floating chargers, multi-channel controllers, chromatographs, data processors, various analytical instruments, radiation level gauges, etc. (7) Other units: various converters (gas/electric, gas/gas, voltage/current, electric/gas), valve positioners, timers, deviation trip amplifiers, instrument solenoid valves (with an interface pipe diameter of 8 mm or more), pressure switches, fork switches, temperature switches, flow switches, level switches, speed switches, electronic limit switches, safety barriers. (8) Various types of actuators. 2. Instruments for which no unit count is performed: The following instruments are not counted on a per-unit basis: (1) Individual components and the corresponding primary instruments are considered as one unit, such as orifice plates, Pitot tubes, thermal resistors, thermocouples, probes, oxidation drills, radiation sources, etc. (2) Instrumentation and automation equipment used for scientific research and development that has not yet been evaluated shall not be included in the statistics of individual units. IV. Methods for counting process control computers and system units: 1. Statistics on systems: Any distributed control system used for monitoring, controlling, operating, and managing the production process, as well as any industrial control computer or microcomputer system that performs all or part of these functions independently, are counted as part of a process computer system. 2. Hardware: Count of devices. Number of units: All independent hardware devices with specific functions that make up a processing system or computer system are counted individually based on their number. (1) Host: Includes electronic units such as the upper-level computer and distributed control system operation stations, configuration workstations, industrial control computers, or microcomputers serving as hosts. (2) External devices: include printers, hard copy machines, disk drives, tape drives, punch machines, photoelectric input devices, electronic typewriters, CRTs, drum drives, card readers, plotters, keyboards, etc. (3) Process interface devices: including detection stations, control stations, I/O units, etc. (4) Network equipment: includes communication controllers and data hubs, modems, amplifiers, etc. (5) Auxiliary equipment: voltage stabilizing power distribution boxes, auxiliary control consoles, purification rooms, etc. 3. Application software statistics: Application software refers to those composed of digital models, which are used to achieve local optimization, overall optimization or stabilization control, sequence control, advanced control, as well as production management – such software is counted as part of the application software statistics. Note: (1) Regular monitoring, control, or advanced control application software configured from modules is used for statistics within the instrument loop. (2) Application software that has not been evaluated or failed the assessment is not included in the software statistics. 4. Statistics on system input and output points: Regardless of whether there is a control cabinet or not, the count is based on the actual number of points that are connected and in use, including analog input and output points as well as discrete input and output points. V. Statistical methods for circuits and circuit instruments 1. Measurement circuits and circuit instruments: A detection system composed of measuring elements, measuring instruments, and accessories is classified as one measurement circuit. All instruments that make up the measurement circuit are counted based on the number of instrument panels in the measurement circuit. 2. Control circuits and circuit instruments: A control system composed of sensing elements, measuring instruments, regulators (or remote control units), actuators, and accessories is counted as one control circuit; all the instruments that make up this control circuit are counted based on the number of instruments in that control circuit (excluding those used for quality analysis, special instruments, and control circuits related to alarm interlocks). 3. On-line quality analysis circuits and circuit instruments: These are instrument circuits used to analyze or control the composition of certain media or to assess the quality of certain products. They are counted as one on-line quality analysis circuit, with all the instruments involved in that circuit being counted based on the number of instruments in that on-line quality analysis circuit. 4. There are instrument circuits for monitoring special parameters and using specialized instruments (such as online monitors for the operating condition of large-scale units, infrared thermometers, etc.), with a set of special circuits dedicated to statistics. Those forming special circuits are counted based on the number of instruments in those special circuits. 5. Instrument circuits composed of detection elements (one or more), alarms, and interlock devices are counted as one set of alarm interlock circuit. All instruments that make up the alarm interlock circuit are counted based on the number of instruments in that alarm interlock circuit. 6. When the instrument is in two or more circuits at the same time, it is counted only once. VI. Method for counting the static sealing points of instrumentation equipment: Each sealing interface is counted as one sealing point, such as a gasket, a threaded connection, a packing box, etc. Note: Welding areas such as those using electric welding or gas welding are not counted as seal points; however, any leakage present is considered a leak point when calculating the leakage rate. VII. The details regarding instruments that are taken out of use or control for process-related reasons are as follows: (1) During normal production, since some equipment in the plant is not in use, the instruments associated with those devices are also taken out of use; this constitutes a situation where they are not utilized nor under control during production, such as the instruments on standby equipment among multiple pieces of equipment. ”However, the instruments taken out of service for production must be in good standby condition. (2) For units that do not produce for an extended period or are shut down for maintenance for some reason, the instruments are taken out of service and controlled due to process-related reasons.