The normal working pressure of Roots blower depends on its design type (single-stage/two-stage) and manufacturing standards. The following is a detailed classification of pressure range and precautions:
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**1、 Normal pressure range of Roots blower**
|* * Type * * | * * Normal working pressure range * * | * * Short term extreme pressure * * | * * Applicable scenarios * *|
|----------------|----------------------|------------------|----------------------------|
|* * Single level standard type * * | 9.8~58.8 kPa | ≤ 78.4 kPa | Sewage treatment, pneumatic conveying|
|Single stage high-pressure type * * | 58.8~78.4 kPa | ≤ 98 kPa | Vacuum feeding, small aeration|
|* * Double stage series type * * | 98~137 kPa | ≤ 147 kPa | High pressure blowback, special industrial process|
>* * Note * *:
> - 1 Bar ≈ 100 kPa ≈ 10.2 mHO
>- * * Short term ultimate pressure * * refers to the allowable occasional overpressure operation (≤ 30 minutes each time), and long-term overpressure may damage the equipment.
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**2、 The core factors of stress limitation**
1. * * Structural strength**
-The pressure limit of cast iron shells is usually ≤ 1.5 Bar, while steel shells can reach up to 2.0 Bar (customized models).
2. * * Rotor clearance**
-When the pressure is greater than 98 kPa, the gap between the rotor and the shell should be ≤ 0.15 mm, otherwise the leakage will increase dramatically.
3. Temperature rise control**
-During high-pressure operation, the temperature rise of the gas can reach 80-120 ℃, and forced cooling is required (such as installing an intercooler).
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**3、 Selection and usage suggestions**
1. Economic pressure range**
-Single stage fans are preferred to be ≤ 58.8 kPa (0.6 Bar), while two-stage fans are preferred to be ≤ 137 kPa (1.4 Bar).
2. * * Overpressure risk management**
-* * Valve * * must be installed (set to 1.1 times the rated pressure).
-Reserve 10-15 pressure margin in system design.
3. * * Alternative solutions**
-When the demand is greater than 1.4 Bar, it is recommended to use a screw fan or centrifugal compressor instead.
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**4、 Comparison of pressure calibration among various brands**
|* * Brand/Series * * | * * Single stage Calibration Pressure * * | * * Dual stage Calibration Pressure * * | * * Remarks * *|
|----------------|------------------|------------------|------------------------------|
|Shandong | ≤ 58.8 kPa | ≤ 137 kPa | Cast iron shell, universal type|
|Changsha Blower Factory | ≤ 78.4 kPa | ≤ 147 kPa | High pressure models need to be customized|
|Japan Daiko | ≤ 98 kPa | ≤ 196 kPa | Steel shell, expensive|
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**5、 Common User Questions**
-Q: The nameplate indicates a pressure of 0.8 Bar. Can it operate at 0.7 Bar for a long time?
**A * *: Yes, but current and temperature need to be monitored (recommended working pressure ≤ 80 nameplate value).
-Q: What should I do if the air volume decreases after overpressure?
**A * *: Check system resistance (such as pipeline blockage), or replace with a higher power fan.
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**Summary**
The normal pressure for a single stage Roots blower is 0.8 Bar, and for a double stage it is 1.4 Bar. Exceeding this range requires special design, and the overall benefits are lower than other types of compressors. When selecting, it is necessary to match the system requirements to avoid overloading the equipment caused by "small horses pulling big cars".
