Rack Mout Energy Storage Battery zhejiang ttn electric co.,ltd , https://www.ttnpower.com
Instrument Design Selection
Instrument design selection is based on the fundamental requirement to meet the conditions of the process measurement medium and the monitoring function. The selected instruments should be technically advanced, reliable, easy to maintain and install, and economically viable. All design regulations must follow a uniform set of guidelines.
First, flow meters are chosen based on the pipe diameter. For pipes with a nominal diameter (DN) of 50 or larger, an orifice plate differential pressure flow meter is typically used. For pipes smaller than DN 50, a rotameter is preferred. If the process media conditions do not allow for this type of flow meter, alternative types may be considered.
For liquid level measurement, a differential pressure level gauge is generally used for continuous measurement. However, if the measuring range is less than 2000mm, it may not be suitable, and in such cases, an external float level gauge or other alternatives can be applied.
Pressure gauges and differential pressure gauges must be selected based on the process conditions. Local pressure gauges usually have a dial size of 100mm or 150mm. At pump outlets, anti-vibration pressure gauges are recommended. For strong corrosive, crystallizing, solid particle-laden, or highly viscous fluids, diaphragm pressure gauges are preferred.
Temperature instruments require clear specifications for the thermowell form, size, and material. Bimetallic thermometers are commonly used for local temperature measurement. Pt100 resistance thermometers are generally preferred for general applications (-200°C to 400°C). Special requirements should be addressed by selecting the appropriate type, and within the same factory, the number of thermal resistance types should be minimized.
Control valve sizing and selection involve calculating the Cv value and determining the valve size based on the medium's characteristics. The valve type, actuator, packing, and bonnet style must be chosen accordingly. Safety considerations, such as power failure scenarios, must also be taken into account. Material, rated pressure, connection mode, and sealing surface type are additional factors to consider.
Alarm and interlock systems must include sound and light alarms outside of DCS functions. Emergency stop interlock systems should meet specific on-site contact and functional requirements.
Instrument panels should be designed with consideration for installation height, power supply, piping direction, wiring, and air piping. DCS systems must specify components, equipment specifications, monitoring functions, redundancy, and communication protocols. Cable routing from the control room should also be planned.
Instrument installation material statistics cover various aspects, including guide pressure piping, heating materials, public works piping, gas supply piping, pneumatic signal piping, cables, steel threading pipes, wiring materials, and other related items. Each category has specific calculation methods and estimated quantities based on actual measurements and design diagrams.
The material quantities are calculated differently depending on whether the instrumentation points are confirmed or not. For example, high-pressure or special material pipes require a 20% increase in the estimated quantity. Valves, fittings, flanges, bolts, nuts, and gaskets are all counted based on the "meter installation diagram" or actual quantities.
In addition, for steam heating, electric heat tracing, and gas supply systems, the lengths of pipes, valves, and fittings are calculated using similar principles. Pneumatic signal cables, multi-core and single-core cables, grounding wires, and cable trays are also included in the material statistics.
Finally, wiring materials such as junction boxes, compression joints, crimped terminals, and cable labels are accounted for with some adjustments for extra quantities. Other materials like cable trays, columns, angle iron, channels, steel plates, and flat steel are estimated based on the project's needs.
This detailed approach ensures that all instrument design and installation requirements are met efficiently and accurately, contributing to the overall success of the project.
September 29, 2025