This standard specifies the correspondence between altitude and air pressure, water depth and water pressure in nature, and provides a basis for the formulation of application environment condition standards and product standards for storage, transportation and use of electrical and electronic products, or for selecting the severity level. GB 4797.2-1986 Natural environment conditions for electrical and electronic products Altitude and air pressure, water depth and water pressure GB4797.2-1986 Standard download decompression password: www.bzxz.net

Scope of application
National Standard of the People's Republic of China
Environmental conditions for electric and electronic products
Altitude and air pressure, depth and water pressure
Environmental conditions for electric and electronic products appearing in natureAltitude and air pressure, depth and water pressure
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GB4797.2—86
This standard specifies the correspondence between altitude and air pressure, water depth and water pressure in nature, and provides a basis for the formulation of application environmental condition standards and product standards for storage, transportation and use of electric and electronic products or the selection of severity levels. Note: For the influence of air pressure and water pressure on the performance of electric and electronic products, refer to the appendix. 2 Altitude and air pressure
The corresponding relationship between altitude and average air pressure is shown in Table 1. 2.1
Altitude, m
2 The corresponding relationship between altitude and extreme minimum air pressure is shown in Table 2. 2.2
Published by the National Bureau of Standards on July 31, 1986
Average air pressure, kPa
Implemented from August 1, 1987 to August 1
Altitude, m
GB4797.2—86
Extreme minimum air pressure, kPa
Note: The extreme minimum air pressure in the table is lower than the cumulative extreme minimum air pressure value observed regularly on the ground in each year. 3 Water depth and water pressure
The corresponding relationship between water depth and water pressure is shown in Table 3.
Water depth, m
Note: The water in the table refers to the pressure value of clean water, not including the air pressure component. 58
Water pressure, kPa
100×10
150×10
200×10
300×10
400×10
100×102
200×102
300×102
400×102
500×102
GB4797.2-86
Appendix A
Influence of air pressure and water pressure on the performance of electrical and electronic products (reference)
A.1 According to the statistical results of meteorological data in my country and around the world, the air pressure values ​​at the same altitude vary due to different locations or measurement times. For example, the average standard air pressure at sea level is 101.325 kPa, while the actual measured value fluctuates between 91% and 107%. A.2 According to the test results, low air pressure has a significant impact on some electrical properties of products, which is often not negligible, and corresponding protective measures should be taken. The main ones are: A.2.1 As the air pressure decreases, the corona (initial and disappearing corona) voltage of electrical products decreases, and the external insulation electrical strength also decreases. Under normal circumstances, for electrical products in the range of 0 to 5000m above sea level, for every 12% decrease in air pressure (equivalent to an increase of 1000m in altitude), the corona voltage and external insulation electrical strength decrease by 8% to 13%. Similar phenomena also exist in aviation electrical and electronic products. A.2.2 As the air pressure decreases, the air density also decreases accordingly, resulting in a decrease in heat dissipation capacity, leading to an increase in the temperature rise of products that use natural convection, forced ventilation or air radiators as the main heat dissipation methods. Generally speaking, for electrical products at an altitude of 0 to 5000m, the temperature rise increases by 3% to 10% for every 12% decrease in air pressure (equivalent to an increase of 1000m in altitude). Aviation electrical and electronic products are also affected to varying degrees.
A.2.3 When the air pressure decreases, the switching capacity and electrical life of switchgear products with free air as the arc extinguishing medium are affected to a certain extent. A.3 The decrease or increase in air pressure and the increase in water pressure have a certain impact on the mechanical properties and structure of the product, among which the main ones are: A.3.1 The decrease or increase in air pressure and the increase in water pressure will increase the pressure difference between the inside and outside of the sealed container of the product, which is likely to cause gas or liquid to leak outward or penetrate inward from the sealed joint of the sealed container, and may even cause the container to rupture. A.3.2 The decrease in air pressure will accelerate the volatilization or evaporation of fillers and solvent substances contained in some materials, causing the materials to accelerate aging and failure.
Additional Notes:
This standard was proposed by the National Technical Committee for Environmental Technology Standardization of Electrical and Electronic Products. This standard was drafted by the "Pressure" Working Group of the Technical Committee for Environmental Technology Standardization of All-Electronic Products.
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