Code of practice for ventilation in petrochemical plants and refineries
1988 Edition

Overview of Scope and Design Principles (Clause 4.2)

• Pertains to the design of ventilation and air handling systems for petrochemical and refinery settings.
• Highlights methods for effective heat extraction and removal of contaminants.
• Covers specifications for flameproof electrical enclosures, centrifugal and propeller fans, and air filtration equipment.

Ventilation System Specifications (Clause 4.2.7.1)

Key Points:

• Air supply should be either forced or a combination of forced supply and positive exhaust.
• Exhaust systems must include ducting, grills, fans, and chimneys.
• Air flow rates are designed to control temperature rise and dilute contaminants.

Air Change Rate Formula:

[ ACH = \frac{Q \times 60}{V} ]

where:

• Q = volumetric airflow rate (m³/min)
• V = volume of space (m³)
• ACH = air changes per hour

flowchart LR
    HeatRemoval[Heat Removal System] -->|Forced Supply| AirFlowHeat[≥12 ACH]
    ContaminantRemoval[Gas/Contaminant Removal] -->|Mechanical Exhaust| AirFlowContaminant[12-20 ACH]
    AirFlowHeat & AirFlowContaminant --> VentilationGoal[Maintain Temperature & Air Quality]

Refer to relevant clauses and referenced IS codes within IS 12332 for comprehensive fan, filter, and enclosure requirements.

IS 12332 Terminology and Key Details

Clause 2.0 - Definitions:

• Establishes uniform terminology throughout the standard.
• Defines terms related to flameproof enclosures, fans, air filters, and ventilation components.

Clause 4.2 - Design Basis:

• Sets design criteria for electrical devices and ventilation equipment ensuring safety and functionality.

Clause 7.3 - Recommended Duct Velocity by Medium:

Clause 22.5 - Testing and Specifications:

• Details test procedures for flameproof enclosures.
• Specifications for propeller and centrifugal fans.
• Methods for testing panel-type air filters used in ventilation and air conditioning.

Summary:

• Use duct design velocities from Clause 7.3 according to the material handled.
• Consult Clause 22.5 for fan and enclosure testing protocols.
• Clause 2.0 ensures consistent use of terminology.

flowchart TD
    Definitions[Definitions (Clause 2.0)] --> DesignBasis[Design Basis (Clause 4.2)]
    DesignBasis --> DuctVelocities[Duct Velocities (Clause 7.3)]
    DuctVelocities --> TestingSpecs[Testing & Specifications (Clause 22.5)]

Refer to the full IS 12332 document for detailed design and testing information.

IS 12332: Location Selection Criteria for Buildings

Clause 3.2 - Area Classification:

• Prefer siting buildings in electrically safe (non-hazardous) zones to minimize the need for expensive hazardous equipment.
• Avoid placement in densely populated areas to reduce potential risk.
• Ensure adherence to the Environment Protection Act, 1986.
• Take into account environmental factors and site surroundings.

Clause 3.3 - Wind Influence:

• Reduce infiltration by strategically placing cracks, crevices, and window openings.
• Design openings to minimize air infiltration considering prevailing wind directions.

Key Definition - Wet Bulb Temperature (Clause 2.23):

• Temperature measured by a thermometer with a wetted bulb exposed to airflow ≥ 4.5 m/s.
• Important for HVAC and ventilation system design.

Practical Recommendations:

flowchart LR
    SiteSelection[Select Site] --> AreaClass{Area Classification}
    AreaClass -->|Non-Hazardous| Proceed[Proceed]
    AreaClass -->|Hazardous| Reconsider[Reconsider Location]
    Proceed --> WindAnalysis[Analyze Wind Direction]
    WindAnalysis --> OpeningPlacement[Place Openings to Reduce Infiltration]
    OpeningPlacement --> ComplianceCheck[Check Environmental Compliance]
    ComplianceCheck --> Finalize[Finalize Location]

This approach promotes safety, cost-efficiency, and environmental responsibility in building placement.

IS 12332: Essential Design Considerations

1. Design Foundation (Clause 4.2):

• Account for wind conditions to minimize infiltration through cracks and openings.
• Position openings to limit air leakage and maintain structural integrity.

2. Duct Design Velocities (Clause 7.3, Table 7.1):

• These velocities ensure efficient transport without excessive wear or pressure loss.

3. Additional Specifications (Clause 22.5):

• Flameproof electrical apparatus enclosures.
• Specifications for propeller and centrifugal fans.
• Testing protocols for panel-type air filters.

Design Workflow for Ventilation Ducts

flowchart TD
    WindAssessment[Assess Wind Conditions] --> OpeningLocation[Locate Openings to Reduce Infiltration]
    OpeningLocation --> MediumSelection[Select Conveying Material]
    MediumSelection --> VelocityDetermination[Determine Design Velocity per Table 7.1]
    VelocityDetermination --> DuctFanDesign[Design Ducts and Fans Accordingly]
    DuctFanDesign --> ComplianceChecks[Apply Flameproof and Testing Standards]

Proper selection based on conveyed medium and design velocity ensures system durability, efficiency, and compliance.

IS 12332: Key Formulas and Component Specifications

1. Air Flow Rates for Ventilation (Clause 4.2.7.1):

• Heat dissipation requires a minimum of 12 air changes per hour.
• Temperature in pits should not exceed ambient by more than 5°C.
• Gas and contaminant removal systems should provide between 12 to 20 air changes per hour, depending on process needs.

2. Use of Air Washers (Clause 4.2.8):

• Employed to maintain desired relative humidity and dry bulb temperature.
• Effective for filtering dust and gaseous pollutants.
• Particularly useful in areas with significant sensible heat generation.

3. Related Standards for Components (Clause 22.5):

Air Change Rate Calculation:

[ \text{Air Flow Rate (m}^3/\text{hr)} = \text{Space Volume (m}^3) \times \text{Air Changes per Hour} ]

System Components Diagram:

flowchart LR
    ConditionedSpace -->|Heat Removal| ForcedSupplyAndExhaust[Forced Supply + Exhaust Ventilation]
    ConditionedSpace -->|Gas Removal| MechanicalExhaust[Mechanical Exhaust System]
    ConditionedSpace -->|Humidity Control| AirWasher[Air Washer]
    ForcedSupplyAndExhaust -->|≥12 ACH| TempControl[Maintain ≤5°C Temp Rise]
    MechanicalExhaust -->|12-20 ACH| ContaminantRemoval[Remove Pollutants]
    AirWasher -->|Filter Dust & Gases| HumidityControl[Maintain RH & Temperature]

Refer to Clauses 4 and 22 of IS 12332 for detailed component design and testing requirements.

IS 12332: Installation and Operation Highlights

1. Temperature Monitoring (Clause 5.5.5):

• Provide temperature indication within work areas.
• Maintain temperatures within prescribed limits.

2. Ventilation System Requirements (Clause 4.2.7.1):

• Heat removal via forced supply or combined forced supply and positive exhaust.

• Airflow must restrict pit temperature increases to no more than 5°C above ambient.

• Minimum of 12 air changes per hour for heat removal.

• For gas and contaminant extraction:

  • Employ mechanical exhaust systems including ducts, grills, blowers, and chimneys.
  • Air exchange rates between 12 and 20 ACH depending on processes.

3. Air Change Rate Calculation:

[ ACH = \frac{60 \times Q}{V} ]

Where:

• Q = volumetric airflow (m³/min)
• V = volume of the room or pit (m³)

4. Summary Table of Ventilation Requirements:

flowchart LR
    HeatSource --> Workroom[Work Room]
    Workroom --> ForcedSupply[Forced Supply Ventilation]
    Workroom --> MechanicalExhaust[Mechanical Exhaust Ventilation]
    ForcedSupply --> TempControl[Maintain ≤5°C Temp Rise]
    MechanicalExhaust --> ContaminantRemoval[Remove Gases/Contaminants]
    TempControl & ContaminantRemoval --> VentilationEffectiveness[Maintain 12-20 ACH]

Refer to Clause 22.5 and associated standards for detailed technical specifications on flameproof enclosures, fans, and filters.

IS 12332: Key Points on Testing and Evaluation

1. Factory Testing of Filters (Clause 7.1):

• Panel-type air filters for ventilation and air-conditioning are tested under IS 7613-1975.
• Tests include dust holding capacity, airflow resistance, and particulate removal efficiency.

2. Specifications Covered (Clause 22.5):

• Flameproof enclosures for electrical devices.
• Propeller AC ventilating fans (first revision).
• Centrifugal fans.
• Test methods for panel-type air filters.

3. Critical Testing Parameters and Formulas:

• Airflow (Q):

[ Q = A \times V ]

where:

• A = cross-sectional area (m²)

• V = air velocity (m/s)

• Pressure Drop (ΔP):

• Measured across filters to determine resistance.

• Filter Efficiency (η):

[ \eta = \frac{C_{in} - C_{out}}{C_{in}} \times 100% ]

where:

• C_in = particle concentration before the filter
• C_out = particle concentration after the filter

4. Example Test Parameter Ranges:

For exact testing protocols and values, consult IS 7613-1975 for filters and respective IS codes for fans and enclosures.

flowchart LR
    AirIntake --> Filter[Filter]
    Filter --> PressureDrop[Measure ΔP]
    Filter --> ParticleOut[Measure Particle Concentration Out]
    AirIntake --> ParticleIn[Measure Particle Concentration In]
    ParticleIn & ParticleOut --> EfficiencyCalc[Calculate Efficiency η]

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