Twin Lobe Roots Air Blowers are widely used in STP, ETP, aquaculture, biogas, and pneumatic conveying applications because they deliver constant airflow and stable pressure. However, most blower failures occur due to improper erection, back pressure, continuous overheating, and poor maintenance.

To ensure long life and reliable performance:

Install the blower above tank level

Maintain correct pipe size and avoid excessive bends

Never reduce discharge pipe diameter

Install NRV and Pressure Relief Valve

Maintain proper gear oil level (SAE 90/140)

Do not run continuously without standby rotation

Keep operating pressure ideally between 0.1–0.3 kg/cm² for aeration

Avoid pressure above 0.4 kg/cm² to prevent overheating

Back pressure is the main reason for temperature rise, oil leakage, bearing damage, and frequent breakdowns. Using proper pipeline design, pressure monitoring, and temperature-based auto changeover systems can significantly increase blower life and reduce maintenance cost.

Twin Lobe Roots Air Blower Erection, Operation & Maintenance Guide

How to Avoid Back Pressure & Frequent Failures in STP / ETP Applications

Twin Lobe Roots Air Blowers are widely used in STP (Sewage Treatment Plants), ETP (Effluent Treatment Plants), Aquaculture, Biogas Plants, Cement Handling, and Pneumatic Conveying Systems.

However, many industries face frequent overheating, oil leakage, seal damage, and bearing failures — mainly due to improper erection and operation.

In this article, we explain:

• Proper erection procedure

• How to avoid back pressure

• Common mistakes causing failures

• Preventive maintenance best practices

What is a Twin Lobe Roots Air Blower?

A Twin Lobe Roots Blower is a positive displacement (PD) blower that delivers constant air volume regardless of pressure variations (within rated limits).

It is ideal for aeration applications where consistent oxygen supply is critical.

1️⃣ Proper Erection of Twin Lobe Roots Blowers

Correct installation is the foundation for long blower life.

 1. Install Above Tank Level

Never install the blower below tank water level.
Installing below tank level causes:

• Back pressure

• Temperature rise

• Oil seal leakage

• Frequent breakdown

• Short equipment life

Always install at top level or above tank platform.

 2. Check Motor Rotation Direction

Before full operation:

• Run motor briefly

• Confirm rotation matches arrow mark on blower

Wrong rotation causes:

• Immediate back pressure

• Internal damage

• Gear failure

 3. Maintain Correct Pipe Size

Do NOT reduce pipe size after blower outlet.

✔ Pipe diameter must match or be larger than blower outlet
✔ Avoid excessive bends
✔ Avoid vertical discharge lines above 2 meters without proper design

When using two blowers into common header:

👉 Header pipe must be double the size of single blower outlet.

 4. Install NRV & Pressure Relief Valve (PRV)

Always install:

• Non Return Valve (NRV) – prevents reverse airflow

• Pressure Relief Valve – set slightly below max rated pressure

This protects blower during shutdown and pressure spikes.

 5. Proper Pulley & Belt Alignment

• Use straight edge for alignment

• Belt tension not too tight / not too loose

• Avoid vibration

Improper alignment leads to bearing and shaft damage.

 6. Gear Oil Lubrication

Use recommended gear oil (SAE 90 / SAE 140).

✔ Maintain oil level between MIN and MAX
✔ Never run without oil
✔ Use high-quality lubricant only

Running without oil for even one minute can damage gears and bearings.

 Understanding Back Pressure – Main Reason for Failures

Back pressure is the number one reason for blower overheating and frequent spare replacement.

What Happens When Pressure Exceeds 0.4 kg/cm²?

When discharge pressure increases:

1. Blower casing temperature rises

2. Oil viscosity reduces

3. Oil seal starts leaking

4. Bearings and gears wear out

5. Shaft damage occurs

Even if blower rated for 0.7 kg/cm², continuous high pressure reduces lifespan drastically.

Ideal Pressure for STP & ETP Aeration

For biological aeration:

✔ 0.1 to 0.3 kg/cm² is ideal
❌ Above 0.4 kg/cm² causes heat and microorganism stress

High-pressure hot air can damage aerobic bacteria growth in aeration tanks.

3️⃣ Don’ts in Roots Blower Operation

❌ Do not reduce pipeline size
❌ Do not use excessive bends
❌ Do not run with delivery valve closed
❌ Do not operate above rated pressure
❌ Do not use wrong motor HP or RPM
❌ Do not run continuously without rest
❌ Do not install in poorly ventilated room
❌ Do not disassemble without expert tools

Most failures are not brand issues — they are erection and operation mistakes.

4️⃣ Avoid Continuous Running – Use Auto Changeover System

Running one blower continuously causes overheating.

Recommended Solution:

✔ Install Timer / PLC controller
✔ Temperature-based auto changeover
✔ Maintain standby blower

Example:

• Blower A runs

• When temperature reaches 50°C → Stop

• Blower B starts

• First blower cools down

This reduces thermal stress and increases life.

5️⃣ Maintenance Schedule for Long Life

🔹 Daily

     Check Oil lubrication

• Check noise

• Check vibration

• Check oil level

🔹 Weekly

   Grease applying for pulley side 2 place ( tempresture base weeking 2 wise or 1 wise )

• Clean air filter

• Inspect belt tension

• Check foundation bolts

🔹 Monthly

• Log temperature

• Check pressure gauge readings

• Inspect lubrication - 200 hours once chenge gear oil

🔹 Quarterly

• Pressure drop analysis

• Minor internal inspection

🔹 Annually

• Full overhaul if required

• Replace oil seals & bearings if worn

Preventive maintenance is cheaper than breakdown repair.

Why Positive Displacement Blowers Are Used in STP & ETP?

Twin Lobe Roots Blowers are preferred because:

✔ Constant airflow
✔ Stable pressure
✔ Energy efficient
✔ Low maintenance
✔ Suitable for continuous operation
✔ Long service life

Additional Applications

Twin Lobe Roots Blowers are used in:

• Aquaculture (Shrimp & Fish Hatcheries)

• Cement & Fly Ash Conveying

• Sugar Industry

• Paper & Pulp Industry

• Chemical Plants

• Electroplating Tanks

• Food Processing

Conclusion

Most Twin Lobe Roots Air Blower failures are caused by:

• Improper erection

• Back pressure

• Wrong pipeline design

• Continuous overheating

• Poor lubrication

By following correct installation practices and pressure control, you can increase blower life by 2–3 times and reduce maintenance cost drastically.

Need Technical Support?

For blower selection, erection guidance, service, and annual maintenance support:

SAI AIR INDUSTRY
Industrial Air & Water Handling Equipment
Website: https://saiblowers.com
Email: [email protected]

Serving Chennai, Coimbatore, Pondicherry,Bengaluru, Hyderabad, Kochi & all South India.

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