Professional Technical Guide for Explosion proof Roots Blowers
1、 Explosion proof rating and certification standards
1. Explosion proof certification system:
-ATEX (EU): II 2G Ex db IIC T4 Gb
- IECEx（）：Ex db IIC T4 Gb
-NEC (USA): Class I, Division 1, Group B/C/D
2. * * Chinese Explosion proof Standards * *:
-GB3836.1-2021 General Requirements for Explosive Environments
-GB3836.2-2021 Explosion proof Type "d"
-Typical symbol: Ex d IIC T4 Gb
3. * * Temperature group selection * *:
|Group | Surface Temperature | Applicable Gas Types|
|---|---|---|
|T1 | 450 ℃ | Hydrogen, acetylene, etc|
|T4 | 135 ℃ | Most combustible gases|
|T6 | 85 ℃ | High sensitivity gas|
2、 Key explosion-proof structure design
1. * * Explosion proof enclosure requirements * *:
-Material: HT250 cast iron (anti explosion pressure ≥ 1.5MPa)
-Joint surface parameters:
-Flat gap ≤ 0.15mm
-Length ≥ 12.5mm
-Roughness Ra ≤ 3.2 μ m
2. * * Special explosion-proof components * *:
-Explosion proof motor: Ex d IIB T4 (standard)
-Explosion proof junction box: dual chamber structure
-Explosion proof control box: with overload protection
3. * * Gap Control * *:
-Dynamic clearance between rotors ≥ 0.4mm
-Shell clearance ≤ 0.2mm
-Triple explosion-proof seal is used at the shaft seal
3、 Selection of Technical Parameters Calculation
1. Explosion limit considerations:
LEL (explosion limit) coefficient ≥ 1.5
Calculation formula: Q=Q theory x (1-LEL)/DEL
2. Requirements for Pressure Vessels:
Pmax ≤ 0.8 × P design (explosion-proof coefficient)
Shell burst pressure ≥ 1.5 times the working pressure
3. * * Thermodynamic Calculation * *:
Surface temperature ≤ T group limit -20 ℃
Exhaust temperature control ≤ 100 ℃ (with added cooler)
4、 Typical explosion-proof configuration scheme
1. * * Chemical industry configuration * *:
-Material: 316L stainless steel
-Sealing: Double mechanical seal+nitrogen protection
-Monitoring: Temperature+Vibration+Pressure Three Parameters
2. Petroleum industry configuration:
-Explosion proof grade: Ex d IIC T4
-Supporting equipment: flame arrester+valve
-Coating: H2S corrosion resistant treatment
3. * * Pharmaceutical industry configuration * *:
-Oil free design
-All stainless steel structure
-CIP cleaning interface
5、 Installation and maintenance specifications
1. * * Explosion proof area division * *:
-Installation requirements for Zone 0/1/2
-Distance ≥ 3m (from potential release source)
2. * * Special installation requirements * *:
-Grounding resistance ≤ 4 Ω
-Cable: Flame retardant armored cable
-Pipeline: static bridging treatment
3. * * Maintenance precautions * *:
-Disable non explosion proof tools
-Gas detection is required during maintenance
-Seal replacement cycle ≤ 1 year
6、 Interlocking system
1. * * Basic protection functions * *:
-Shutdown due to temperature exceeding the standard (≥ 95 ℃)
-Vibration protection (≥ 7.1mm/s)
-High pressure protection (1.1 × Pmax)
2. * * Intelligent monitoring system * *:
-Online gas concentration detection
-Real time monitoring of bearing status
-Explosion proof PLC control system
7、 Common fault handling
|Fault phenomenon | Explosion proof related reasons | Solution|
|---|---|---|
|Overheating of shell | Blockage of heat sink | Shutdown for cleaning|
|Abnormal spark | rotor friction | adjusting clearance|
|Seal leakage | Seal aging | Replace explosion-proof seal|
8、 Mainstream products in the market
1. * * Domestic explosion-proof series * *:
-Ex series (Ex d IIB T4)
-BT series (Ex d IIC T4)
-Price range: 7.5kW, 45000 to 60000 yuan
2. * * Imported Explosion proof Series * *:
-EX series (ATEX certified)
-D series
-Price range: 7.5kW, 120000 to 180000 yuan
Note: When selecting, it is necessary to provide information such as explosion hazard zone classification map and medium characteristic table. It is recommended to conduct explosion-proof performance testing every quarter to ensure operation. For special working conditions, a HAZOP analysis is required to determine the final plan.
