ATEX Roots Blower

An ATEX roots blower is designed for operation in potentially explosive atmospheres – where flammable gases, vapors, or dusts may be present. ATEX certification is mandatory for equipment used in EU hazardous areas and is required under the ATEX Directive 2014/34/EU. For roots blowers, ATEX compliance involves explosion-proof motors, spark-resistant rotors, gas-tight seals, temperature monitoring, and certified construction.

Based on commissioning experience across chemical plants, oil refineries, biogas facilities, and grain handling operations, ATEX roots blowers are essential for safety in explosive environments. Non-ATEX blowers in hazardous areas create explosion risk – and legal liability.

This guide covers ATEX requirements, equipment categories, gas and dust groups, temperature classes, and procurement considerations for hazardous area applications.

Table of Contents

• What Is an ATEX Roots Blower?

• ATEX Directive Overview

• ATEX Equipment Categories

• Gas and Dust Groups

• Temperature Classes

• ATEX Requirements for Roots Blowers

• Main Components – ATEX Upgrades

• Types Comparison Table

• Industrial Applications

• Engineering Advantages

• Common Problems and Troubleshooting

• Selection Guide

• Performance and Engineering Calculations

• Cost Factors and Pricing

• Procurement Considerations

• Frequently Asked Questions

• Final Thoughts

What Is an ATEX Roots Blower?

An ATEX roots blower is a positive displacement rotary lobe machine designed and certified for use in potentially explosive atmospheres. ATEX certification ensures the blower does not create ignition sources – sparks, hot surfaces, or static electricity – that could ignite explosive gas or dust mixtures.

ATEX roots blowers incorporate:

• Explosion-proof motors (Ex d, Ex e, Ex n)

• Spark-resistant rotors (aluminum, bronze, stainless steel)

• Non-sparking materials

• Gas-tight seals

• Temperature monitoring (T-class)

• Grounding and static dissipation

• ATEX certification from a notified body

Based on hazardous area installation records, ATEX roots blowers are mandatory for biogas, chemical, oil and gas, grain handling, and pharmaceutical applications with explosion risk. Non-ATEX blowers in these applications are a serious safety hazard.

ATEX Directive Overview

ATEX Directive 2014/34/EU:

• Applies to equipment and protective systems in potentially explosive atmospheres

• Covers electrical and non-electrical equipment

• Requires certification by notified body for Category 1 and 2

• Requires documentation and marking

• Mandatory for EU member states

Key requirements:

• Equipment must not create ignition sources

• Equipment must withstand internal explosions (if applicable)

• Equipment must be clearly marked with ATEX classification

• Technical documentation must be maintained

Notified body:

• An organization designated by an EU member state

• Assesses conformity of equipment

• Issues ATEX certificate

• Assigns notified body number (appears on certificate and marking)

ATEX Equipment Categories

Equipment categories define the level of protection required:

For roots blowers:

• Category 2G is most common (Zone 1 gas applications)

• Category 3G for Zone 2 (less hazardous)

• Category 2D for Zone 21 dust applications

• Category 3D for Zone 22 dust applications

Gas and Dust Groups

Gas groups (based on ignition energy):

Dust groups:

For roots blowers:

• IIB is common for biogas, chemical, oil and gas

• IIC for hydrogen, acetylene (higher cost)

• IIIB for grain, coal, wood dust

Temperature Classes

Temperature class defines maximum surface temperature:

For roots blowers:

• T3 or T4 is typical

• Must be below autoignition temperature of gas

• Temperature monitoring and shutdown required

• Higher classes (T4-T6) require more cooling

ATEX Requirements for Roots Blowers

1. Explosion-proof motor.

• Ex d (flameproof): most common for roots blowers

• Ex e (increased safety): less common

• Ex n (non-sparking): for Zone 2

• Motor must be ATEX certified

2. Spark-resistant rotors.

• Aluminum: lightweight, spark-resistant

• Bronze: non-sparking, higher strength

• Stainless steel: corrosion resistant, spark-resistant

• Cast iron not acceptable for ATEX

3. Non-sparking materials.

• Casing: ductile iron with coating or stainless steel

• Hardware: non-sparking materials

• Gaskets: anti-static materials

4. Gas-tight seals.

• Labyrinth seals with buffer gas

• Double lip seals with purge

• Magnetic seals (zero leakage)

• Prevent gas leakage to atmosphere

5. Temperature monitoring.

• Thermocouple at discharge

• Automatic shutdown at set temperature

• T-class compliance

6. Grounding.

• All piping and equipment grounded

• Static electricity dissipation

• Grounding straps on flanges

7. ATEX marking.

• CE marking with notified body number

• ATEX classification (II 2G c T4, etc.)

• Equipment identification

Main Components – ATEX Upgrades

Rotor (impeller). Most critical for ATEX compliance. Cast iron not acceptable – sparks on impact. Options: aluminum (lightweight, spark-resistant), bronze (non-sparking, higher strength), stainless steel (corrosion + spark-resistant). Expected lifespan: 25,000–40,000 hours. Failure mode: wear from abrasives.

Timing gears. Helical gears standard. Must be non-sparking materials. Inspection: measure backlash annually (0.05–0.10 mm).

Bearings. C3 or C4 clearance standard. Must be designed for temperature monitoring. Lifespan: 25,000–35,000 hours.

Casing. Ductile iron with epoxy coating or stainless steel. Must be conductive (grounding).

Shaft seals. Gas-tight seals mandatory – labyrinth with buffer gas, double lip with purge, or magnetic. Failure mode: gas leakage creates explosion hazard.

Motor. Ex d (flameproof) most common. Must be ATEX certified for gas group and temperature class.

Temperature monitoring. Thermocouple at discharge with shutdown at T-class limit.

Grounding. All components grounded.

Types Comparison Table

For ATEX, three-lobe with spark-resistant rotors and Ex d motor is standard.

Industrial Applications

Biogas and landfill gas. Methane (50–70%), explosive. ATEX Zone 1 or 2. Category 2G, IIB, T3/T4. Stainless steel rotors. Explosion-proof motor. Gas-tight seals. Temperature monitoring.

Chemical plants. VOCs, hydrogen, solvents. ATEX Zone 1 or 2. Category 2G, IIB or IIC. Spark-resistant rotors. Gas-tight seals. Ex d motor.

Oil and gas refineries. Hydrocarbons, hydrogen. ATEX Zone 1 or 2. Category 2G, IIB or IIC. Bronze or stainless rotors. Ex d motor.

Grain handling. Grain dust explosions. ATEX Zone 21 or 22. Category 2D or 3D. Spark-resistant rotors. Dust-tight seals. Grounding.

Coal handling. Coal dust explosions. ATEX Zone 21 or 22. Category 2D or 3D. Hard-chrome or tungsten carbide rotors. Dust-tight seals.

Pharmaceutical. Flammable solvents, dust. ATEX Zone 1 or 2 (gas), Zone 21 (dust). Category 2G or 2D. Stainless steel. Ex d motor.

Wastewater treatment. Digester gas (methane). ATEX Zone 2. Category 3G, IIB, T3. Stainless steel. Ex n motor.

Based on ATEX installation records, biogas and chemical are the largest applications for ATEX roots blowers.

Engineering Advantages

Safety. ATEX roots blowers are designed to prevent ignition of explosive atmospheres. Non-ATEX blowers are not safe for hazardous areas.

Compliance. ATEX certification is mandatory for EU hazardous areas. Non-ATEX equipment cannot be legally installed.

Reliability. ATEX components are designed for rigorous service. Explosion-proof motors, gas-tight seals, and temperature monitoring ensure reliable operation.

Debris tolerance. Roots blowers handle particulates and moisture better than other technologies.

Simple maintenance. Plant mechanics can rebuild ATEX blowers (with proper training). No specialized tools.

Common Problems and Troubleshooting

Selection Guide

Step 1 – Define ATEX classification.
Zone (0, 1, 2 for gas; 20, 21, 22 for dust). Gas group (IIA, IIB, IIC). Temperature class (T1–T6). Category (1, 2, 3).

Step 2 – Define gas/dust properties.
Gas composition, ignition temperature, explosion limits. Dust type, conductivity.

Step 3 – Select rotor material.
Aluminum: general ATEX. Bronze: higher strength. Stainless steel: corrosion + spark-resistant.

Step 4 – Select motor type.
Ex d (flameproof): most common. Ex e (increased safety): less common. Ex n (non-sparking): Zone 2.

Step 5 – Specify seals.
Labyrinth with buffer gas. Double lip with purge. Magnetic (zero leakage).

Step 6 – Specify temperature monitoring.
Thermocouple with shutdown at T-class limit.

Step 7 – Verify ATEX certification.
Notified body certificate. Current and valid. Matches equipment.

Common selection mistakes for ATEX roots blower:

• Specifying non-ATEX motor

• Cast iron rotors – spark hazard

• No temperature monitoring

• Standard seals – gas leakage

• No grounding

• Wrong ATEX category for zone

Performance and Engineering Calculations

Power calculation:
BHP = (ACFM × psig) / (229 × ηmechanical × ηmotor)
ATEX motors may have lower efficiency. Use manufacturer data.

Temperature monitoring limits:
T-class limit minus 20°C safety margin.
Example: T4 (135°C) → shutdown at 115°C (239°F).

Grounding requirements:
Resistance to ground < 1 ohm. All piping and equipment bonded.

ATEX Roots Blower vs Alternatives

Decision criteria:

• Choose ATEX roots: corrosive/abrasive gas, moderate pressure, debris tolerance

• Choose ATEX screw: clean gas, high pressure, efficiency priority

• Choose ATEX liquid ring: wet gas, water available

Cost Factors and Pricing

ATEX roots blower cost components (100 HP class, 2026):

Complete ATEX package (100 HP blower):

• ATEX blower: $20,000–35,000

• Ex d motor: included

• Silencers: $1,500–2,500

• VFD (Ex d enclosure): $6,000–10,000

• Total FOB: $30,000–50,000

Annual operating cost:

• Electricity: $52,000

• Maintenance: $3,000–5,000

• Total annual: $55,000–57,000

Procurement Considerations

When requesting quotes for ATEX roots blower:

1. Specify ATEX classification.
Zone, gas group, temperature class. Category. Provide all application details.

2. Require ATEX certificate from notified body.
Check certificate is current. Verify notified body number. Match equipment.

3. Specify spark-resistant rotors.
Aluminum, bronze, or stainless steel. Cast iron not acceptable.

4. Specify explosion-proof motor.
Ex d, Ex e, or Ex n. Must match ATEX classification.

5. Specify gas-tight seals.
Labyrinth with buffer gas. Double lip with purge. Magnetic.

6. Specify temperature monitoring.
Thermocouple with shutdown. T-class limit minus 20°C margin.

7. Specify grounding.
All components grounded. Resistance < 1 ohm.

8. Request documentation.
ATEX certificate, Declaration of Conformity, technical file, test reports.

Red flags when sourcing ATEX roots blower:

• Cannot provide ATEX certificate from notified body

• Cast iron rotors

• Standard motor (not Ex d/e/n)

• No temperature monitoring

• Unfamiliar with ATEX requirements

Frequently Asked Questions

1. What is an ATEX roots blower?
An ATEX roots blower is a positive displacement rotary lobe machine designed and certified for use in potentially explosive atmospheres. It incorporates explosion-proof motors, spark-resistant rotors, gas-tight seals, temperature monitoring, and ATEX certification from a notified body. It is required for hazardous area applications in the EU.

2. What ATEX classification do I need?
Depends on application. Zone 1 (gas): Category 2G. Zone 2 (gas): Category 3G. Zone 21 (dust): Category 2D. Zone 22 (dust): Category 3D. Gas group: IIA (propane), IIB (ethylene), or IIC (hydrogen). Temperature class: T1–T6 (must be below gas ignition temperature). Consult ATEX specialist.

3. What motors are used for ATEX roots blowers?
Ex d (flameproof) is most common – motor enclosure can contain internal explosion. Ex e (increased safety) – less common. Ex n (non-sparking) – for Zone 2 only. Motor must be ATEX certified for the gas group and temperature class.

4. What rotor materials are used for ATEX roots blowers?
Aluminum: lightweight, spark-resistant. Bronze: non-sparking, higher strength. Stainless steel: corrosion resistant, spark-resistant. Cast iron is not acceptable – can create sparks on impact. Material selection depends on gas composition and application.

5. What seals are required for ATEX roots blowers?
Gas-tight seals are mandatory – gas leakage creates explosion hazard. Labyrinth seals with buffer gas (nitrogen or air). Double lip seals with purge. Magnetic seals (zero leakage). Gas detection recommended. Standard lip seals are not acceptable.

6. Is temperature monitoring required for ATEX roots blowers?
Yes – temperature monitoring is mandatory. Discharge temperature must stay below T-class limit. Thermocouple with automatic shutdown at T-class limit minus 20°C margin. Bearing temperature monitoring recommended.

7. What is the difference between ATEX and non-ATEX roots blowers?
ATEX blowers have explosion-proof motors, spark-resistant rotors, gas-tight seals, temperature monitoring, grounding, and ATEX certification. Non-ATEX blowers use standard motors, cast iron rotors, standard seals, and no ATEX certification. Non-ATEX blowers are not safe for hazardous areas.

8. How much does an ATEX roots blower cost?
ATEX roots blowers cost 100–200% more than standard blowers. Example: 100 HP standard blower $8,500–11,000. 100 HP ATEX blower $20,000–35,000. Premium includes Ex d motor, spark-resistant rotors, gas-tight seals, temperature monitoring, and ATEX certification.

9. What is the payback for ATEX?
ATEX is not about payback – it is about safety and legal compliance. Non-ATEX equipment in hazardous areas creates explosion risk, legal liability, and insurance issues. The cost of ATEX equipment is justified by safety and compliance requirements.

10. Can I convert a standard blower to ATEX?
Not easily. ATEX requires certified components (motor, seals, rotors) and notified body certification. Converting a standard blower would require replacing motor, rotors, seals, adding temperature monitoring, and ATEX certification. Usually more cost-effective to purchase ATEX blower.

11. What documentation is required for ATEX?
ATEX certificate from notified body, Declaration of Conformity, technical file (risk assessment, drawings, test reports), installation and maintenance instructions, and ATEX marking on equipment. Request documentation before shipment.

12. How long does ATEX certification take?
8–16 weeks depending on manufacturer and notified body. Plan ahead for hazardous area projects. Zhanggu and other established manufacturers can provide ATEX-certified blowers with proper documentation.

13. What is the notified body?
A notified body is an organization designated by an EU member state to assess conformity of ATEX equipment. The notified body issues the ATEX certificate. The notified body number appears on the certificate and CE marking.

14. Can ATEX roots blowers handle dust?
Yes – ATEX roots blowers are available for dust applications (Zone 21, 22). Dust ATEX requires Category 2D or 3D, dust-tight seals, spark-resistant rotors, grounding, and dust-tight construction. Grain, coal, wood, and pharmaceutical dust applications require dust ATEX.

15. What are the maintenance requirements for ATEX roots blowers?
Regular maintenance is critical – ATEX components must remain in certified condition. Replace seals preventively. Check temperature monitoring. Verify grounding. Inspect rotors for wear. Document all maintenance. Non-certified repairs void ATEX certification.

Final Thoughts

After commissioning ATEX roots blowers for hazardous area applications, here is my practical advice:

Selection logic. For any hazardous area application, specify an ATEX roots blower with the correct category, gas group, and temperature class. Spark-resistant rotors (aluminum, bronze, stainless steel), Ex d motor, gas-tight seals, and temperature monitoring are mandatory. Zhanggu and other established manufacturers offer ATEX-certified blowers.

ATEX is about safety – not cost. The premium for ATEX equipment (100–200% over standard) is justified by explosion prevention and legal compliance. Non-ATEX equipment in hazardous areas creates explosion risk and legal liability. The cost of an explosion far exceeds the cost of ATEX equipment.

Certification is non-negotiable. ATEX certification from a notified body is required. Request the ATEX certificate, Declaration of Conformity, and technical file before shipment. Verify the certificate is current. Non-certified "ATEX-style" equipment is not acceptable.

Maintenance preserves certification. ATEX blowers must be maintained in certified condition. Replace seals on schedule. Verify temperature monitoring. Document maintenance. Non-certified repairs void ATEX certification and create risk.

The bottom line. ATEX roots blowers are mandatory for hazardous area applications. The safety and compliance requirements are not optional. Specify correctly. Verify certification. Maintain properly. The blower will operate safely in explosive environments.