Code of Practice for Industrial Ventilation

Scope of IS 3103: Ventilation for Control of Air Contaminants

IS 3103 specifies ventilation requirements to control air contaminants in industrial and commercial environments. Key points include:

Key Specifications:

• Capture Velocity: Air velocity at the contaminant release point to prevent escape.
• Volume of Air Required: Based on opening area × capture velocity.

Recommended Capture Velocities (Table 3):

Additional Notes:

• Threshold limit values for contaminants refer to ACGIH latest publications.
• Calculated or observed values should be rounded as per IS 2:1960.

flowchart TD
    A[Contaminant Released] --> B{Velocity of Release}
    B -->|No velocity| C[Capture Velocity 0.25-0.5 m/s]
    B -->|Low velocity| D[Capture Velocity 0.5-1.0 m/s]
    B -->|Active generation| E[Capture Velocity 1.0-2.5 m/s]
    B -->|High velocity| F[Capture Velocity 2.5-10 m/s]
    C --> G[Calculate Air Volume = Area × Capture Velocity]
    D --> G
    E --> G
    F --> G

This ensures effective capture and control of contaminants as per IS 3103 scope.

IS 3103 - 1975: Key Definitions & Formulas for Ventilation

Key Definitions (Clause 2.0)

• Definitions relate to ventilation parameters, such as inlet/outlet openings, air flow rates, and forces causing air movement (wind, temperature difference).
• 'A' = Area of opening (smaller of inlet/outlet when unequal).

Important Formulas & Concepts

1. Air Flow Increase due to Unequal Openings (Clause 6.2.3.3):
   When inlet and outlet areas differ, use the smaller area 'A' in flow calculations.
   Actual air volume increases by a percentage from Fig. 1 (ratio of outlet to inlet).

2. Combined Effect of Wind and Temperature Difference (Clause 6.2.3.2):

   • Express air due to temperature difference as % of total air flow.
   • Use Fig. 2 to find actual flow caused by combined forces.

Figures Overview

Summary Table (Conceptual)

flowchart LR
    A[Inlet Opening Area] -->|Smaller area| Calc[Flow Calculation]
    B[Outlet Opening Area] -->|Smaller area| Calc
    Wind[Wind Effect] --> Combine[Combined Forces]
    Temp[Temperature Difference] --> Combine
    Combine --> Fig2[Use Fig. 2 for multiplier]
    Calc --> Fig1[Use Fig. 1 for % increase]
    Fig1 & Fig2 --> FinalFlow[Actual Air Flow Volume]

**Use IS 3103 Fig. 1 & 2 for precise % increases and multipliers in ventilation design involving natural

IS 3103 - General Requirements: Key Specifications & Tables

1. Temperature Rise (Clause 4.3.1.2)

• Defines allowable temperature rise between outside air and inlet openings.
• Used mainly for ventilation design in industrial/general buildings.

2. Definitions (Clause 2.0)

• Establishes terms related to ventilation and temperature control.

3. Design Considerations

• Temperature rise guides air supply system design to maintain comfort and function.
• Use values in Table 2 as a general guide for summer months.

Summary:
For ventilation design, maintain temperature rise within limits based on outlet height to ensure functional air supply and comfort.

flowchart LR
    A[Outside Air] -->|Temperature Rise| B[Inlet Openings]
    B --> C[Building Interior]
    note right of B
      Temperature Rise depends on
      outlet height (6, 9, 12 m)
    end

IS 3103: Key Design Considerations

1. Maximum Permissible Wet Bulb Temperatures (Clause 4.3.3)

• Note: Efficiency decreases with rising dry bulb temperature even if wet bulb is controlled.
• Cooling (e.g., refrigeration) is recommended if conditions exceed these limits.

2. Allowable Temperature Rise for Outside Air Supply (Clause 4.3.1.2)

• Temperature rise = difference between outside air and inlet air temperatures.

3. Sun-breakers (Clause 3.1.1)

• Provide sun-breakers to block direct sunlight, reduce heat radiation, and avoid glare.

4. Capture Velocities for Air Contaminants (Clause 4.5.1.1)

flowchart TD
    A[Outside Air] -->|Temperature Rise| B[Inlet Openings]
    B --> C{Height of Outlet}
    C -->|6

IS 3103: Safety and Noise Control – Key Points

Noise Control (Clause 5.3)

• Focus: Design and installation of motors, fans, ducts to ensure quiet operation.
• Goal: Minimize noise transmission in noisy manufacturing processes.
• Approach:
  • Use vibration isolators.
  • Select low-noise equipment.
  • Employ silencers and acoustic enclosures.
  • Design ductwork with smooth bends and proper sizing to reduce turbulence noise.

Ventilation for Control of Air Contaminants (Clause 4.5 & Table 3)

Formula for Air Volume (Q):

[ Q = A \times V_c ]

• Q: Volume of air required (m³/s)
• A: Area of contaminant opening (m²)
• V_c: Capture velocity (m/s) from Table 3 based on contaminant dispersion

Summary

• Noise Control: Design for quiet motors/fans, use silencers, vibration isolation.
• Ventilation: Calculate air volume using contaminant opening area and capture velocity from Table 3.
• Capture velocity depends on contaminant release velocity and environment.

flowchart LR
    A[Contaminant Source] --> B[Capture Velocity Selection]
    B --> C{Condition of Dispersion}
    C -->|No velocity| D[0.25-0.5 m/s]
    C -->|Low velocity| E[0.5-1.0 m/s]
    C -->|Active generation| F[1.0-2.5 m/s]
    C -->|High velocity| G[2.5-10 m/s]
   

IS 3103: Testing and Performance Evaluation - Key Points

1. Testing Procedure (Clause 6.1)

• Agreement on test objectives, methods, duration, accuracy, and equipment condition is mandatory.
• Tests should be conducted during normal working hours.
• Equipment must be properly adjusted before testing.

2. Environmental Conditions (Clause 4.3.3)

• Note: Human efficiency declines with rising dry bulb temperature even if wet bulb is controlled.
• Long exposure to 50°C dry bulb / 27°C wet bulb can be dangerous.
• Cooling methods like refrigeration are recommended if conditions exceed these limits.

3. Safety Requirements (Clause 8.2)

• Follow IS:1646-1961 for electrical wiring and fire safety.
• Separate codes for systems ≤650V and >650V apply.
• Fire safety of electrical installations must comply with relevant building codes.

Summary Formula for Wet Bulb Temperature Limits

[ T_{wb, max} = f(T_{db}) \quad \text{(from table above)} ]

Where:

• ( T_{wb, max} ) = Maximum permissible wet bulb temperature (°C)
• ( T_{db} ) = Dry bulb temperature (°C)

flowchart TD
    A[Test Planning] --> B{Agreement on:}
    B --> B1[Test Objectives]
    B --> B2[Methods & Duration]
    B --> B3[Accuracy Required]
    B --> B4[Equipment Condition]
    B --> C[Conduct Test during Normal Hours]
    C --> D[Adjust Equipment Properly]
    D --> E[Evaluate Performance]

For detailed electrical safety and fire safety, refer to IS:1646-1961 and relevant codes of practice.

IS 3103: Operation and Maintenance - Key Points & Tables

Clause 5.4: Operation & Maintenance Essentials

• Access: Provide easy access for inspection, cleaning, and repair.
• Space: Ensure reasonable clearance during operation.
• Controls: Locate dampers and controls for quick, easy operation.
• Lighting & Ventilation: Adequate lighting and ventilation at operation/maintenance points.

Key Tables from IS 3103

1. Maximum Permissible Wet Bulb Temperatures (Clause 4.3.3)

Note: Efficiency drops with higher dry bulb temps; avoid long exposure at 50°C dry bulb.

2. Allowable Temperature Rise for Outside Air Supply (Clause 4.3.1.2)

3. Recommended Capture Velocities for Exhaust Systems (Clause 4.5.1.1)

Summary:

• Design for easy maintenance access and control.
• Maintain wet bulb temps within prescribed limits for worker safety.
• Use **capture velocities

Safety Requirements for Electrical Equipment (IS 3103: Clause 8)

Key References:

• Fire safety aspects per IS 1646-1961
• Electrical wiring per IS 732-1963 (Wiring rules)
• Electrical installations per IS 2274-1963 (General requirements)
• Indian Electricity Act & Rules compliance mandatory

Important Specifications:

• Voltage Limits:

  • Wiring installations for systems not exceeding 650 V: Follow IS 732.
  • Systems exceeding 650 V: Refer to relevant codes of practice.

• Fire Safety:

  • Materials and equipment must comply with IS 1646 for fire resistance.
  • Electrical equipment should minimize fire hazards by proper insulation, grounding, and protection devices.

• Inspection & Maintenance:

  • Cooling/heating units and air filters must be inspected frequently for corrosion/dirt.
  • Corroded parts must be cleaned and treated with anti-corrosion paint.

Summary Table: Safety Checks for Electrical Equipment

Typical Formula for Minimum Conductor Size (from IS 732):

[ I = \frac{P}{V \times \text{Power Factor} \times \sqrt{3}} \quad \Rightarrow \quad A = \frac{I}{k} ]

• (I) = Current (A)
• (P) = Power (W)
• (V) = Voltage (V)
• (A) = Cross-sectional area of conductor (mm²)
• (k) = Current carrying capacity per mm² (from IS tables)

flowchart TD
    A[Electrical Equipment] --> B[Wiring Installation]
    B --> C{Voltage ≤ 650V?}
    C -- Yes --> D[Follow IS 732]
    C -- No --> E[Follow High Voltage Code]