Code of Practice for Fire Safety of Industrial Buildings: Coal Pulverizers and Associated Equipments

IS 3595: Scope Summary & Key Specifications

• Scope: Covers storage and handling of raw coal, focusing on safety and fire prevention.
• Definitions: Uses IS 8757 definitions plus additional specific terms (Clause 3.0).
• Coal Heap/Stack Width Limits (Clause 7.5, Table 2):

• Purpose: Restrict coal heap width based on fire hydrant availability to minimize fire risk.
• Reference: IS 3595:2002 (Reaffirmed 2007), ICS codes 91.040.20; 13.220.20.

Visual Summary

graph LR
A[Coal Heap/Stack] --> B{Fire Hydrants Availability}
B -->|One Side| C[Max Width = 45 m]
B -->|Two Opposite Sides| D[Max Width = 90 m]

This ensures safe coal storage dimensions relative to firefighting infrastructure.

IS 3595 - Definitions Summary

• Scope: Clause 3.0 states that definitions from IS 8757 apply, plus additional ones specific to IS 3595.
• Key Definition Context: Related to fire safety in coal storage and handling.
• Important Parameters:

• Fire Safety Measures (Clause 12.12): Fire hydrants, hoses, fittings, and automatic fire detection/extinguishing devices must be maintained per good fire brigade practices.

Practical Use

• When designing coal storage heaps, ensure width limits based on fire hydrant availability to minimize fire risk.
• Maintain firefighting equipment as per Clause 12.12 for compliance and safety.

flowchart LR
    A[Coal Heap/Stack] --> B{Fire Hydrants Availability}
    B -->|One Side| C[Max Width = 45 m]
    B -->|Two Opposite Sides| D[Max Width = 90 m]
    C & D --> E[Safe Fire Management]

This concise summary aids in understanding the key definitions and related specifications in IS 3595 for fire safety in coal storage.

IS 3595: General Requirements for Storage of Raw Coal

Key Specifications from Clause 7.5 (Table 2):

Important Notes:

• The width limits ensure adequate fire safety access.
• Fire hydrants must be strategically located based on heap width.
• Refer to Clause 7.3.7 for detailed fire hydrant placement requirements.

Additional General Requirements (from IS 3595 & related codes):

• Storage heaps should be stable with proper slope angles to prevent collapse.
• Adequate drainage to avoid water accumulation.
• Regular inspection and maintenance of fire safety equipment.

flowchart LR
    A[Coal Heap/Stack] --> B{Fire Hydrants Availability}
    B -->|One Side| C[Max Width = 45 m]
    B -->|Two Opposite Sides| D[Max Width = 90 m]
    C --> E[Ensure fire safety access]
    D --> E

This ensures safe coal storage with fire protection per IS 3595.

IS 3595 Key Points for Pulverizing and Burner Systems Design

Pulverizer Design (Clause 4.12.1)

• Must achieve required coal fineness.
• Compatible with blower/compressor capacity.
• Ensure minimum velocity in ducts to prevent coal dust settling.
• Typical minimum velocity: 20–25 m/s in coal-air mixture ducts.

Burner System Design (Clause 4.13)

• Continuous supply of coal dust-air mixture.
• Stable flame under all operating conditions.
• Operating limits matched to furnace design and fuel characteristics.

Safety (Clause 11.5)

• If pulverizing not under inert atmosphere:
  • Install automatic CO₂ or halon fire extinguishing systems per IS 6382.
  • Protect bins, ducts, pulverizers.

Typical Design Formula for Velocity in Coal Dust-Air Mixture Ducts

[ V = \frac{Q}{A} ] Where:

• (V) = velocity (m/s)
• (Q) = volumetric flow rate of coal-air mixture (m³/s)
• (A) = cross-sectional area of duct (m²)

Summary Table

flowchart LR
    A[Coal Feed] --> B[Pulverizer]
    B --> C[Blower/Compressor]
    C --> D[Coal Dust-Air Mixture Ducts]
    D --> E[Burner System]
    E --> F[Furnace Flame]
    B -. Fire Protection .-> G[CO₂/Halon System]

This ensures proper pulverization, transport, and combustion with safety provisions.

IS 3595: Key Specifications for Coal Storage and Handling

1. Coal Heap/Stack Construction (Clause 7.3.8)

• Each successive coal layer must be mechanically compacted to avoid cavities.
• Slope of heap sides ≤ 30° to maintain stability.

2. Maximum Permissible Height of Coal Heap/Stack (Table 1, Clause 7.3.6)

3. Coal Heap Shape and Access (Clause 7.3.4)

• Heap/stack shape: Oblong with a 3 m wide access-way around.
• Masonry bins/enclosures must have at least one open side, preferably on the leeward side.
• Access road must be along the open side.

4. Precautions Against Spontaneous Combustion (Clause 4.3)

• Bulk coal is prone to spontaneous heating.
• Ensure adequate ventilation and monitoring.
• Avoid mixing heated coal with fresh coal.

flowchart LR
    A[Coal Layer] --> B[Mechanical Compaction]
    B --> C[No Cavities]
    C --> D[Stack Formation]
    D --> E{Slope ≤ 30°?}
    E -- Yes --> F[Stable Heap]
    E -- No --> G[Risk of Collapse]

This ensures stable, safe coal storage per IS 3595.

IS 3595: Ventilation and Explosion Protection Key Points

Explosion Vent Area Requirements

Additional Specifications

• Building Construction: Preferably single-storeyed for coal handling areas.
• Driers: Must have explosion vents discharging outdoors with wire mesh protection.

Summary Formulae

[ A_v = \frac{V}{k} ]

Where:

• ( A_v ) = Minimum vent area (m²)
• ( V ) = Volume of bin/pipe/room (m³)
• ( k ) = Volume factor (6 for piping, 10 for bins and rooms)

Vent Layout Diagram (Simplified)

flowchart TB
    A[Coal Pulverizing Building]
    A -->|Roof Vents (1m²/10m³)| B[Explosion Vents]
    B --> C[Hinged Windows (Open Outward)]
    A --> D[Pulverized Coal Bins]
    D -->|Vents 1m²/10m³| E[Explosion Vents]
    A --> F[Piping]
    F -->|Vents 1m²/6m³, ≤3m apart| G[Explosion Vents]
    A --> H[Driers]
    H -->|Vents to outdoors + Wire mesh| I[Protected Vent Openings]

Ensure all vent areas meet minimum requirements and are properly located for effective explosion relief and personnel safety.

Fire Prevention Measures as per IS 3595 (Clause 12)

• Fire Hydrants, Hose & Fittings: Must be maintained following good fire brigade practices (Clause 12.12).
• Automatic Fire Detection & Extinguishing Devices: Installation and maintenance should conform to IS 2175 (heat detectors) and IS 2189 (automatic fire detection and alarm systems).
• Fire Spark & Temperature Sensing Devices (Clause 10):
  • Spark detectors at conveyor belt inlets.
  • Temperature sensors on rollers and driers.
  • Fixed temperature heat detectors (linear type) on conveyors and cable ducts.
  • Manual electrical fire alarms with call boxes wired in closed circuits on 12/24 V batteries.
• Liaison with Fire Brigade: Close coordination with local fire brigade for rapid response (Clause 11.7).

Key IS References for Fire Safety Equipment:

Summary Diagram of Fire Prevention System:

graph LR
A[Coal Pulverizer Plant] --> B[Fire Spark Detectors]
A --> C[Temperature Sensors]
A --> D[Heat Detectors (IS 2175)]
A --> E[Automatic Fire Alarm System (IS 2189)]
A --> F[Fire Hydrants & Hose]
A --> G[Manual Call Boxes]
B & C & D & E & G --> H[Control Panel]
H --> I[Local Fire Brigade Coordination]

Maintain all devices per IS standards and ensure continuous monitoring and quick fire brigade response for effective fire prevention.

IS 3595 Key Specifications for Equipment and Machinery Safety

1. Pressure Design for Equipment (Clause 8.2)

• Equipment near atmospheric pressure (driers, pulverizers, bins, cyclones, conveyors, fan/pump casings) must withstand:
  • Internal pressure = 3.5 kgf/cm²
• For equipment operating above atmospheric pressure:
  • Design pressure = 3.5 kgf/cm² × (working pressure in atmospheres)

2. Storage of Flammable Materials (Clause 7.5)

• Store paints, oils, and flammable materials away from coal pulverizing plant.
• Only keep immediate use quantity near the plant.

3. Lighting (Clause 9.8.1)

• Pendant lighting must be suspended by threaded rigid conduit stems for safety.

4. Fire, Spark, and Temperature Detection (Clause 10)

• Install detectors for:
  • Sparks/hot coal at conveyor starts.
  • Continuous temperature monitoring of drive/idle rollers.
  • Temperature limiting thermostats in driers.
  • Temperature monitoring of coal-air mixture leaving pulverizers.
  • Fixed linear heat detectors (IS 2175) on conveyors and cables.
  • Manual electrical fire alarms with audiovisual indication, wired on 12/24 V battery.

Summary Table: Equipment Pressure Design

flowchart TD
    A[Machinery & Equipment] -->|Pressure Design| B{Pressure Level}
    B -->|Near Atmosphere| C[3.5 kgf/cm²]
    B -->|Above Atmosphere| D[3.5 × Working Pressure]
    A --> E[Fire & Temperature Sensors]
    E --> F[Sparks Detection @ Conveyor Start]
    E --> G[Roller Temperature Monitoring]
    E --> H[Coal-Air Mixture Temperature]
    E --> I[Fixed Heat Detectors (IS 2175)]
    A --> J[Flammable Materials Storage]
    J --> K[Away from Plant, Immediate Use Only]

This concise summary aligns with

IS 3595 - Coal Driers Key Points

Definitions & Location (Clauses 3.6, 5.2, 8.9)

• Coal Drier: Equipment for drying solid or pulverized coal in an inert atmosphere.
• Must be housed in a separate building or fire-resisting compartment with effective separating walls to prevent fire hazards.

Specifications (Clause 8.9)

• Coal driers should be designed considering:
  • Inert atmosphere maintenance to avoid explosion risks.
  • Structural support for heavy equipment and dynamic loads.
  • Adequate ventilation and fire protection.

Related Equipment (Clause 8.12)

• Coal feeders feed coal into driers or pulverizers; their design must ensure smooth flow and safety.

Typical Design Considerations (from engineering practice):

• Thermal expansion of drier shell:
  [ \Delta L = \alpha \times L \times \Delta T ] where (\alpha) = coefficient of thermal expansion, (L) = length, (\Delta T) = temperature difference.

• Fire resisting walls: Minimum 2-hour fire resistance rating recommended.

Summary Table: Coal Drier Structural Requirements

flowchart LR
    A[Coal Storage] --> B[Coal Feeder]
    B --> C[Coal Drier (Inert Atmosphere)]
    C --> D[Pulverizer]
    D --> E[Boiler / Furnace]

    subgraph Safety Measures
        direction TB
        F[Fire Resisting Walls]
        G[Separate Building]
    end

    C --> F
    C --> G

For detailed structural design, refer to IS 3595 clauses on fire walls, loadings, and equipment supports.

IS 3595: Key Specifications & Guidelines for Conveyor Systems (Clause 8.8 - Belt Conveyors)

Material & Safety Specifications

• Fire Resistance:

  • All belts must be fire-resistant for strategic systems, shuttle conveyors over bunkers, transfer conveyors at bunker ends, and conveyors inside buildings/enclosed gantries (8.8.11).

• Conveyor Housing:

  • Construct housing and floors from non-combustible materials: steel, corrugated iron, asbestos sheets, or concrete (8.8.6.1).
  • Provide access points for maintenance inside conveyor housing.

Maintenance & Operational Care

• Pay special attention to the rear of the conveyor (8.8.12):
  • Regularly clean and lubricate rotating parts (pulleys, idlers).
  • Avoid over-lubrication and prevent jamming from coal spillage.

Typical Design Formula for Belt Tension (General Knowledge)

[ T = \frac{W \times L \times f}{\sin \alpha} ]

Where:

• (T) = Belt tension (N)
• (W) = Weight of material on the belt (N/m)
• (L) = Length of conveyor (m)
• (f) = Coefficient of friction
• (\alpha) = Angle of wrap on pulley (radians)

Conveyor Safety & Maintenance Diagram

flowchart LR
    A[Conveyor Belt] --> B[Pulleys & Idlers]
    B --> C[Lubrication & Cleaning]
    C --> D[Prevent Coal Spillage]
    D --> E[Fire Resistant Belting]
    E --> F[Non-Combustible Housing]
    F --> G[Maintenance Access Points]

For detailed design, refer to IS 3595 full text and related standards on belt conveyor design and fire safety.

IS 3595: Fire Detection & Extinguishing Systems - Key Points

Fire Detection Devices (Clause 10)

• Spark detectors at conveyor belt starts (raw & crushed coal).
• Temperature sensors on drive & idle rollers (continuous monitoring).
• Thermostats for dryers to shut down on dangerous temps.
• Temperature monitors on coal-air mixture leaving pulverizer.
• Fixed temperature heat detectors (linear type per IS 2175) for:
  • Belt conveyors
  • Power/control cables (installation per IS 2189)
• Manual electrical fire alarm call boxes:
  • Glass panel break activates alarm.
  • Wired in closed circuit, 12/24 V battery-operated, trickle charged.
  • Control panel duplicated in plant and fire brigade watch rooms.

Fire Extinguishing Equipment (Clause 11)

• Portable CO2 extinguishers per IS 2878 or approved halon alternatives.
• Extinguisher capacity: 6 kg minimum (except inconvenient locations).
• ABC Class dry powder extinguishers recommended instead of fixed halon systems (Clause 11.5).
• Extinguishers placed near electric motors, switchgear, hazardous locations, floors, compartments.

Maintenance (Clause 12.12)

• Fire hydrants, hoses, fittings, and automatic detection/extinguishing devices maintained per good fire brigade practices.

Summary Table of Key Equipment

Fire Alarm Call Box Wiring (Conceptual)

IS 3595: Maintenance and Operational Safety - Key Points

1. Manufacturer's Instructions (Clause 12.10):

   • Always follow the manufacturer's safety and maintenance instructions for pulverizers and related equipment.
   • Keep a copy of these instructions at each operator's station for ready reference and compliance checks.

2. Conveyor Maintenance (Clause 8.8.13):

   • Regularly inspect and maintain conveyor belts to prevent:
     • Friction from belt slipping on drive/idle rollers.
     • Misalignment or belt slippage causing jams.
   • Ensure proper tension and alignment to avoid operational hazards.

3. Safety Precautions during Maintenance (Clause 8.17.7):

   • Take strict safety measures during:
     • Welding, cutting.
     • Tank emptying, cleaning.
     • Tank and vent inspections.
   • Use proper PPE and follow lockout/tagout procedures.

4. Fuel and Oil Storage (Clause 8.17):

   • Store fuel and lighting oils safely to prevent fire hazards.
   • Follow specified storage conditions and handling protocols.

Summary Table: Safety Checks and Maintenance Frequency

flowchart TD
    A[Start Operation] --> B[Check Manufacturer's Instructions]
    B --> C[Inspect Conveyor Belt]
    C --> D{Is Belt Aligned & Tensioned?}
    D -- Yes --> E[Proceed with Operation]
    D -- No --> F[Adjust & Repair Belt]
    F --> E
    E --> G[Perform Maintenance Safely]
    G --> H[Follow Safety Precautions (Welding, Cleaning)]
    H --> I[Store Fuel/Oil Safely]
    I --> J[End]

Note: Always prioritize safety by adhering strictly to IS 3595 clauses and manufacturer's guidelines.

IS 3595: Interlocks and Automatic Controls – Key Points

Definitions (Clause 3.15)

• Interlock: Device(s) sensing unsafe conditions or improper sequences, preventing equipment operation or shutting it down.

Interlock Requirements (Clause 8.18)

• Safety: Interlocks must prevent unsafe actions by tripping devices during unsafe conditions.
• No Manual Override: Manual controls cannot override interlocks until faults or sequence errors are corrected.
• Example (8.18.4): In bin and feeder systems, burner line valves cannot open unless the primary air line valve is open (dust-tight valves interlocked).

Typical Interlock Logic (Conceptual)

flowchart TD
    A[Start Operation] --> B{Is Primary Air Valve Open?}
    B -- No --> C[Block Burner Valve Opening]
    B -- Yes --> D[Allow Burner Valve Opening]
    D --> E[Safe Operation]

Practical Specifications

• Use fail-safe interlocks (default to safe state on failure).
• Interlocks should be electrically and mechanically robust.
• Must comply with Clause 9 for electrical equipment installation.

For detailed wiring and control logic, refer to Clause 9 and related electrical standards.

IS 3595: Emergency Preparedness and Training - Key Points

Training Requirements (Clauses 11.6.2 & 11.6.3)

• Fire Hydrants: Sufficient workers must be trained in operating fire hydrants where installed.
• Fire Prevention & Extinguishers: All workers must be trained in fire prevention and use of portable fire extinguishers for incipient stage fires.

Fire Hydrant & Coal Heap Specifications (Clause 7.5, Table 2)

Fire Brigade Liaison (Clause 11.7)

• Maintain close coordination with nearby public fire brigades for rapid response.

Summary Diagram: Coal Heap Width vs Fire Hydrant Availability

graph LR
A[Fire Hydrants on One Side] --> B[Max Width = 45 m]
C[Fire Hydrants on Two Opposite Sides] --> D[Max Width = 90 m]

Ensure:

• Adequate training for fire safety equipment use.
• Proper coal heap dimensions per hydrant availability.
• Coordination with fire services for emergency readiness.

IS 3595 Annexures & Amendments Summary

• Annex A: Lists the Fire Safety Sectional Committee members from various organizations (e.g., Bhabha Atomic Research Centre, Delhi Fire Services, Ministry of Defence). This ensures expert consensus in standard formulation.

• Clause 12.12: Fire hydrants, hoses, fittings, and automatic fire detection/extinguishing devices must be maintained per good fire brigade practices.

• Amendment (Clause 11.5): Replace "fixed halon fire extinguishing systems" with "A B C Class dry powder extinguisher" for fire safety equipment.

• Referenced IS Codes: IS 3595 refers to standards on fire hoses (IS 636), fire hose couplings (IS 903), fire detectors (IS 2175), fire alarm systems (IS 2189), fire extinguishers (IS 2190, IS 2878), CO2 fire extinguishers (IS 2878), and fixed CO2 systems (IS 6382).

Key Fire Safety Equipment Specification Highlights:

Fire Extinguisher Amendment Formula:

• Use A B C Class Dry Powder Extinguisher instead of halon systems, covering:
  • Class A: Ordinary combustibles
  • Class B: Flammable liquids
  • Class C: Electrical fires

Maintenance Best Practice (Clause 12.12):

• Maintain fire hydrants, hoses, fittings, and automatic fire devices as per good fire brigade practices—regular inspection, functional testing, and timely repair.

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