The pressure of a Roots blower depends on its design, material, and purpose, but typically has a clear theoretical limit and practical application range. The following is a detailed analysis:
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**1. Theoretical pressure (design limit)**
-Single stage Roots blower:
-In theory, the outlet pressure of a single-stage Roots blower can reach * * 0.1 MPa (1 Bar, approximately 100 kPa) * *.
-In practical applications, the commonly used pressure range for single-stage fans is * * 9.8~58.8 kPa (0.1~0.6 Bar) * *.
-Double stage series Roots blower:
-By connecting two-stage fans in series, the pressure can be increased to * * 98~137 kPa (1.0~1.4 Bar) * *, but the efficiency is significantly reduced.
**Restrictive factors * *:
-Gap between rotor and shell: Gas leakage increases under high pressure, leading to a sharp decrease in efficiency.
-Temperature rise issue: Compression heat causes deformation of the shell, requiring forced cooling (such as installing an intercooler).
-Structural Strength: As the mechanical load on gears, bearings, and shafts increases, special materials (such as high-strength cast iron or steel shells) are required.
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**2. Pressure range in practical applications**
|* * Fan type * * | * * Common pressure range * * | * * Ultimate pressure (short-term allowable) * * | * * Typical application scenarios * *|
|--------------------|------------------------|--------------------------|--------------------------------|
|* * Standard single-stage Roots * * | 9.8~58.8 kPa (0.1~0.6 Bar) | 78.4 kPa (0.8 Bar) | Sewage treatment, pneumatic conveying|
|High pressure single-stage Roots | 58.8~78.4 kPa (0.6~0.8 Bar) | 98 kPa (1.0 Bar) | Vacuum feeding, small aeration|
|Double stage series Roots * * | 98~137 kPa (1.0~1.4 Bar) | 147 kPa (1.5 Bar) | Special industrial processes (such as high-pressure blowback)|
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**3. Why can't Roots blowers be as high-pressure as air compressors**
-* * Differences in working principles * *:
-Roots blower is a volumetric non internal compression equipment, where gas pressure is generated by system back pressure rather than mechanical compression.
-An air compressor (such as a screw type) actively compresses gas through rotor engagement, achieving a pressure of over 10 bar.
-Leakage and Efficiency:
-When the pressure is greater than 1 Bar, the internal leakage of the Roots blower can reach 30-50, resulting in a significant increase in energy consumption.
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**4. Special high-pressure Roots blower (customized model)**
A few manufacturers have achieved a pressure of * * ≤ 1.5 Bar * * through the following improvements:
-Optimization of rotor profile: high-precision involute or spiral twisted blades are used to reduce leakage.
-* * Material upgrade * *: Steel rotor, ceramic coated shell.
-* * Forced cooling * *: Oil or water cooling systems control temperature rise.
But this type of fan has high cost and complex maintenance, and is only used in special fields such as chemical and military industries.
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**5. Selection suggestions**
-Requirement of 0.6 Bar: It is recommended to use a screw fan or a centrifugal fan instead.
-High pressure+low flow rate: Dual stage Roots can be considered, but efficiency loss (20-40% increase in specific power) needs to be accepted.
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**Summary**
-Conventional pressure of Roots blower: single-stage ≤ 0.8 Bar, two-stage ≤ 1.4 Bar.
-Economic range: 0.1~0.6 Bar (if it exceeds this range, it is recommended to switch to other types of fans).
-Confirmation of key parameters: It is necessary to combine the performance curve chart provided by the manufacturer to avoid equipment damage caused by overpressure operation.
