@Air Compressor
2025-04-11
Why are industrial compressed gases at a pressure of 0.7mpa?
Industrial compressed gases generally use a pressure of 0.7MPa (about 7 kg/cm²), which is a comprehensiveEfficiency, cost, safetyanddevice compatibilityThe specific reasons are as follows:
1. Balance of energy efficiency
- Air compressor efficiency curve
The energy efficiency ratio (EER) of piston/screw air compressors peaks in the range of 0.6-0.8MPa, and energy consumption increases exponentially after exceeding 1MPa.- example: From 0.7MPa to 1MPa, energy consumption increased by about 35%, but gas transmission only increased by 12%.
- Gas volume matching
The pressure of 0.7MPa can cover 80% of the requirements of industrial scenarios (such as pneumatic tools, purging, control valves), avoiding energy waste caused by excessive compression.
2. Compromise between safety and cost
- pipeline economics
- At 0.7MPa, the wall thickness of carbon steel pipes (DN50) only needs to be 4.5mm, and the cost is 20% lower than that of the 1MPa grade.
- Plastic pipes (such as PE100) can be safely used under 0.7MPa, further reducing material costs.
- Leakage risk control
For every 0.1MPa decrease in pressure, leakage is reduced by about 8%. The annual leakage of a 0.7MPa system is 40%-60% less than a 1MPa system.
3. Equipment compatibility
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Tool adaptability
85% of pneumatic tools have a rated working pressure of 0.6-0.8MPa. Outside this range, additional pressure reducing valves are required to increase failure points. -
Adaptation of international standards
ISO 1219, GB/T 3811 and other standards list 0.7MPa as the recommended pressure level to ensure global equipment interchangeability.
4. History and technological evolution
- material limitations: In the early days, the upper pressure limit of cast iron pipes was about 1MPa, and 0.7MPa was widely used as a safety threshold.
- technical inertia: Existing equipment (such as gas tanks and dryers) is mostly designed to 0.7MPa. Upgrading requires the overall replacement of the system, which is costly.
5. Exceptions to special scenes
- high-pressure demand: Painting (requiring 0.5-0.6MPa), laser cutting (requiring 2- 3MPa) and other scenes require secondary pressurization.
- Low pressure optimization: Cleaning scenarios such as food packaging may use 0.4-0.5MPa to reduce the risk of leakage.
Note: Some industries (such as petrochemicals) may adopt pressures below 0.5MPa due to explosion-proof requirements, and need to be designed in conjunction with explosion-proof standards such as ATEX.