Low pressure, also known as "cyclone".In the plane at the same altitude, the central air pressure is lower than the surrounding air pressure.[1]Low pressure. The pressure of a region is compared with that of its surroundings. The place with the lowest pressure is called“low pressure center”。The air in the places with high pressure around will flow to the center, which is just like that in the surrounding mountainswaterThey all converge to the center of the basin.Near the center of the low pressure in the Northern Hemisphere, the wind is blowing toward the center, which is left-handedVortex, and the air blown in rises to form an upward airflow, usually due to bad weather.
Chinese name
Low atmospheric pressure
Foreign name
low-pressure
Alias
low pressure
Features
The moreThe lower the air pressure near the center
Generally, the formation of low pressure is due to the difference of terrain and heat.The general low pressure becomes a cyclone, and the standard of Grade 12 becomestyphoon(Hurricane). Typhoons usually occur in the northwest Pacific Ocean, but also in eastern Australia andWest Indies。
1. ClassificationTropical cycloneThere is a big difference in the strength of.Accordingly, the international standard for tropical cyclone name and grade is: (1) Typhoon (hurricane): near the ground centerMaximum wind speed≥ 32.6m/s (i.e. wind force is above Grade 12).
(2) Tropical storm: the maximum wind speed near the ground center is 17.2-32.6m/s (i.e. wind force is 8-11).The maximum wind speed near the ground center is 24.5-32.6m/s (force 10-11), which is called a strong tropical storm.
(3) Tropical depression: the maximum wind speed near the ground center is 10.8-17.1m/s (wind force level 6-7).China has adopted international regulations since 1989.Previously, China's meteorological department had stipulated that tropical cyclones should be located near the ground centerMaximum wind speed17.2-32.6m/s (i.e. wind force 8-11) scaletyphoon；The maximum wind speed ≥ 32.6m/s (wind force above 12) is called strong typhoon;The maximum wind speed is 10.8-17.1m/s (wind force level 6-7), which is called tropical depression.In order to better identify and track tropical storms and typhoons with strong winds, they are often named or numbered.According to the regulations of China's meteorological department, tropical storms and typhoons that occur west of 150 ° east longitude and north of the equator are numbered in the order of their occurrence every year.For example, Tropical Storm 9306, Severe Tropical Storm 9304 and Typhoon 9302 represent the sixth tropical storm, the fourth severe tropical storm and the second typhoon that occurred west of 150 ° east longitude in 1993.
The low pressure on the earth is distributed inequator。The sub extreme low pressure is distributed at 60 degrees.
influence
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Low pressure refers to the pressure near the ground, which is generally formed on land in summer.The famous low-pressure center is AsiaLow voltage center（Indian low pressure）And Azores Low Pressure Center.Low pressure air flow is upward.The higher the air flow is, the lower the temperature is, so it forms rainfall.Therefore, the low pressure generally brings strong wind and rain to the passing areas.It can alleviate drought.
Low pressure weather
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Pressure is closely related to the weather.Generally speaking, areas with high pressure on the ground tend to have sunny days, while areas with low pressure on the ground tend to have cloudy and rainy days.The high pressure and low pressure here are relative, not the absolute value of atmospheric pressure.The pressure in a certain area is higher than that in the surrounding area, which is called a high pressure area;The pressure in a certain area is lower than that in the surrounding area, which is called a low-pressure area.At the same level, if the pressure distribution is uneven, the air will flow from the high pressure area to the low pressure area.Therefore, the air pressure in a certain area is high, and the air in this area flows out horizontally to the surrounding area.The air above the high pressure area will drop.As the atmospheric pressure increases with the decrease of altitude, the air at high altitude will sufferpressureAs the temperature rises, the condensate in the air will evaporate and dissipate.Therefore, the central area of high pressure is not conducive to the formation of clouds and rain, usually sunny days.
If the air pressure in a certain area is low, the air in the surrounding area will flow into the area in the horizontal direction, which will cause the air in the area to rise. The rising air will expand due to the reduced pressure, the temperature will decrease, and the water vapor in the air will condense. Therefore, the central area of low pressure is often cloudy and rainy.Since the atmospheric pressure is closely related to the weather, each meteorological post observes the local atmospheric pressure at a unified time every day and reports it to the meteorological center as one of the bases for weather forecast.
Low pressure test
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Low pressure test is a test in which the test sample is put into the test chamber (chamber), and then the air pressure in the chamber (chamber) is reduced to the value specified in the relevant standards, and the specified duration is maintained.It is mainly used to determine the adaptability of components, equipment or other products to low pressure environment during storage, transportation and use.The standards for low air pressure are: GB T 2423.21-1991 Basic Environmental Test Procedures for Electrical and Electronic Products Test M Low air pressure test method GJB 150.2-1986 Environmental test method for military equipment Low air pressure (altitude) test
The standards for low pressure test are:
GB T 2423.21-1991 Basic Environmental Test Procedures for Electric and Electronic Products Test M Low Pressure Test Method
GJB 150.2-1986 Environmental Test Methods for Military Equipment Low Pressure (Height) Test
RTCA/Do160E《Environmental test conditions for airborne equipment》
Low pressure pneumatic suction device (also known as negative pressure suction device) is used for conveying bulk solid materials by negative pressure air flow. It is mainly used in the environment where the conveying distance is close and no dust is allowed, such as dust collection conveying system, feed conveying and drying conveying system in food processing industry
The low-pressure pneumatic suction device has simple and reliable equipment, which can transport the materials that are difficult to supply such as garbage, wood chips, slender fibers, etc., and can realize centralized transportation from several places to a single place, and has a certain mixing function.The low-pressure pneumatic suction device is composed of a receiving tank, a filtering device and a fan. The material is sucked into the receiving tank by the low-pressure fan. The gas is filtered and discharged, and the material falls into the receiving bucket. It belongs toDilute phaseIn the pneumatic conveying process, the conveying distance is close (<30m), the gas-solid ratio is low (<1), and the conveying capacity is small (<5t/h).Please indicate the material name, capacity, particle size, service conditions (pressure and temperature), etc. when making an inquiry.
Pneumatic test equipment
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It is mainly used in aviation, aerospace, information, electronics and other fields to determine the environmental adaptability and reliability test of instruments, electrical products, materials, parts, and equipment under the single or simultaneous action of low pressure, high temperature, and low temperature, and to measure the electrical performance parameters when the test piece is energized.
Temperature range: - 40 ℃~+150 ℃ - 70 ℃~+150 ℃
Temperature fluctuation ± 0.5 ℃
When the temperature deviation is ≥ 100 ℃, ± 3.0 ℃ (no load under normal pressure); when the temperature deviation is<100 ℃, ± 2.0 ℃ (no load under normal pressure)
Temperature rise and fall rate 0.7 ℃~1.0 ℃/min (average in the whole process)
Pressure range: normal pressure~1Kpa
± 2Kpa for pressure deviation ≥ 40KPa, ± 0.5Kpa for 4KPa ～ 40KPa, ± 0.1Kpa for ≤ 4KPa,
Cooling rate: normal pressure~1Kpa ≤ 30 minutes (under normal temperature)
Pressure recovery rate 10kpa/Min (adjustable)
Temperature uniformity ≤ 2.0 ℃ (no load under normal pressure)
Material shell Material Anti rust treatment Cold rolled steel sheet (surface plastic spraying)
Liner material: stainless steel plate (SUS304)
Anti rust treatment of pressure bearing materials High quality thick steel plate (surface plastic spraying)
