The working pressure range and selection points of Roots blower are as follows:
---
**1、 Range of work pressure**
1. * * Standard two/three blade Roots blower * *:
-* * Common pressure range * *: 9.8 kPa (0.1 bar)~98 kPa (1.0 bar)
-Ultimate pressure: Some high-pressure models can reach 147 kPa (1.5 bar), but special design is required (such as strengthening the housing and optimizing the gear material).
2. * * Multi stage Roots blower * * (used in series):
-The pressure can reach * * 196 kPa (2.0 bar) * *, but the efficiency is significantly reduced, and it is usually recommended to use a screw fan instead.
---
**2、 Key factors for pressure selection**
1. * * Actual demand pressure * *:
-Calculate the resistance of the pipeline (along the way+locally) and the required pressure of the terminal equipment (such as the water depth of the aeration tank).
-Example: The aeration depth for sewage treatment is 4 meters, requiring a pressure of ≥ 39.2 kPa (0.4 bar).
2. Relationship between pressure and flow rate:
-Roots blower is a positive displacement blower with a basically constant flow rate, and the pressure increases with the increase of end resistance (but limited by motor power).
-Attention: Overpressure operation can cause motor overload and increased impeller wear.
3. * * Special medium influence * *:
-When transporting high-temperature or corrosive gases, the rated pressure should be reduced (such as for gases above 80 ℃, the pressure should be reduced by 10-20).
---
**3、 Typical pressures in different application scenarios**
|* * Application Scenarios * * | * * Required Pressure (kPa) * * | * * Explanation * *|
|--------------------|---------------------|------------------------------|
|Wastewater treatment aeration | 39.2~58.8 (0.4~0.6 bar) | Determined based on water depth and diffuser resistance|
|Pneumatic conveying (granules) | 49~78.4 (0.5~0.8 bar) | The longer the conveying distance, the higher the pressure requirement|
|Vacuum feeding | -49~-78.4 (negative pressure) | Vacuum type Roots blower needs to be selected|
|Combustion assistance | 9.8~29.4 (0.1~0.3 bar) | Low pressure stable flow is sufficient|
---
**4、 Selection precautions**
1. * * Avoid overpressure operation * *:
-The actual working pressure shall not exceed the allowable pressure indicated on the fan nameplate.
-When overpressure occurs, the valve should automatically open (regular valve calibration is required).
2. * * Motor power matching * *:
-When the pressure increases, the power increases approximately linearly, and it is necessary to ensure that the motor has sufficient margin.
-Simplified power formula:
\[
P（kW）≈ \frac{Q（m3/min） \times \Delta P（kPa）}{60} \times 1.2
\]
3. High temperature/altitude correction:
-High temperature environment: The pressure needs to be converted according to the gas density (for example, at 150 ℃, the actual pressure is about 80% of the standard state).
-High altitude areas: The motor power needs to be increased (for every 1000 meters increase in altitude, the power decreases by about 10).
---
**5、 Frequently Asked Questions and Answers**
**Q: Can the pressure of the Roots blower be controlled by adjusting the valve**
A： may not! Closing the valve will increase resistance and cause motor overload. The correct method is:
-Variable frequency speed regulation: Reduce the speed to reduce flow and pressure.
-Bypass pressure relief: Install a return pipe to return excess gas to the inlet.
**Q: Possible reasons for insufficient pressure**
A：
-Impeller wear (increased clearance) → Replace impeller or adjust clearance.
-Pipeline leakage → Check the sealing of flanges and welds.
-Insufficient motor speed → Check voltage and belt tightness.
---
**6、 Maintenance suggestions**
-Check the pressure gauge monthly for normal operation and record the trend of operating pressure.
-Clean the imported filters annually to avoid blockages that may cause negative pressure to rise.
-When operating under long-term overpressure, it is recommended to upgrade the fan model or use it in parallel.
If specific model pressure parameters are required, information such as fan flow rate and power can be provided for further matching!
