Specification for Blower and Exhauster for Fire Fighting
1985 Edition

Overview of Scope - IS 941 Requirements for Firefighting Blowers and Exhausters

Scope:
This standard defines the specifications concerning design, materials, construction, and performance of blowers and exhausters used for firefighting.

Material Specifications (Table 1)

Alternative Power Options (Clause 2.2)

• Where electrical power is accessible, a 3-phase induction motor with 2.2 kW power rating as per IS 325:1978 may substitute the petrol engine.
• Flameproof motor enclosures must comply with IS 2148:1981.

Component Material Flow Diagram

graph TD
    Impeller[Impeller] -->|Aluminium Grade 4423| AluminiumMaterial[IS 617:1975]
    Casing[Casing] -->|Aluminium Grade 4423| AluminiumMaterial
    SuctionMouth[Suction Mouth] -->|Aluminium Grade 4423| AluminiumMaterial
    ExhaustPipe[Exhaust Pipe] -->|Canvas| CanvasMaterial[IS 1424:1977]
    PetrolEngine[Petrol Engine 2.5 kW] -->|Petrol Engine| PetrolEngineSpec[IS 7347:1974]
    DieselEngine[Diesel Engine 3.23 kW] -->|Diesel Engine| DieselEngineSpec[IS 10001:1981]
    Frame[Frame with Handles] -->|Mild Steel Pipe| FrameMaterial[IS 1239 (Part 1):1979]
    WireFabric[Wire Fabric Steel] -->|Steel| WireFabricMaterial[IS 4948:1974]

Key References and Material Standards in IS 941

Engine Alternatives (1993 Amendment):

• Petrol engine of 2.5 kW or a lightweight diesel engine rated at 3.23 kW (IS 10001:1981).

Electric Motor Option:

• 3-phase induction motor of 2.2 kW complying with IS 325:1978, with flameproof enclosures as per IS 2148:1981.

Notes:

• All materials must strictly comply with the specified IS grades.
• Engines and motors should meet their respective IS performance and safety standards.
• Consult individual IS codes for detailed mechanical and electrical design criteria.

flowchart LR
    AluminiumComponents[Impeller, Casing, Suction Mouth] -->|Aluminium Grade 4423| IS617[IS 617-1975]
    ExhaustPipe -->|Canvas| IS1424[IS 1424-1977]
    PetrolEngine -->|2.5 kW Petrol| IS7347[IS 7347-1974]
    DieselEngine -->|3.23 kW Diesel| IS10001[IS 10001-1981]
    Frame -->|Mild Steel Pipe| IS1239[IS 1239 (Part 1)-1979]
    WireFabric -->|Steel| IS4948[IS 4948-1974]
    ElectricMotor -->|2.2 kW Induction Motor| IS325[IS 325-1978]

Definitions and Material Specifications (Clause 3.1, Table 1)

Alternative Power Sources:

• 3-phase induction motor of 2.2 kW as per IS 325:1978, optional flameproof enclosure IS 2148:1981.
• Lightweight diesel engine rated at 3.23 kW per IS 10001:1981.

Component Material Flow Visualization

graph LR
    Impeller -->|Aluminium Grade 4423| BlowerAssembly
    Casing -->|Aluminium Grade 4423| BlowerAssembly
    SuctionMouth -->|Aluminium Grade 4423| BlowerAssembly
    ExhaustPipe -->|Canvas (IS 1424)| BlowerAssembly
    Frame -->|Mild Steel Pipe (IS 1239)| BlowerAssembly
    WireFabric -->|Steel (IS 4948)| BlowerAssembly
    Engine -->|Petrol (IS 7347) or Diesel (IS 10001)| BlowerAssembly

General Requirements of IS 941: Materials and Construction

Alternate Power Source (Clause 2.2):

• A 3-phase induction motor rated at 2.2 kW complying with IS 325:1978 may replace the petrol engine.
• Flameproof motor enclosures should adhere to IS 2148:1981 if required.

Summary:

• Aluminium Grade 4423 is the standard for impeller, casing, and suction mouth.
• Mild steel pipes are specified for frames and handles.
• Exhaust pipes use canvas material.
• Engines and motors must meet the relevant IS standards.
• These material standards ensure durability and compliance with firefighting equipment norms.

graph TD
    BlowerComponents --> Impeller[Impeller - Aluminium (IS 617)]
    BlowerComponents --> Casing[Casing - Aluminium (IS 617)]
    BlowerComponents --> SuctionMouth[Suction Mouth - Aluminium (IS 617)]
    BlowerComponents --> ExhaustPipe[Exhaust Pipe - Canvas (IS 1424)]
    BlowerComponents --> Frame[Frame - Mild Steel Pipe (IS 1239)]
    BlowerComponents --> WireFabric[Wire Fabric Steel (IS 4948)]
    BlowerComponents --> Engine[Engine - Petrol (IS 7347), Diesel (IS 10001), or 3-phase Motor (IS 325)]

Summary of Performance Requirements per IS 941

1. Material Compliance:

2. Engine Performance:

• Diesel engine rated at 3.23 kW per IS 10001:1981.

3. Weight and Mounting:

• Total assembly weight (engine, impeller, fuel) should not exceed 60 kg.
• Impeller is of overhung type mounted on the engine shaft extension.

4. Operational Criteria:

• Equipment must pass performance tests outlined in the standard.
• Testing includes verification of materials, engine output, and assembly integrity.

Additional Notes:

• Test result rounding to follow IS 2:1960.
• Emphasis on ensuring performance reliability and safety during firefighting operations.

flowchart LR
    MaterialSelection --> Manufacturing
    Manufacturing --> Assembly[Engine + Impeller Assembly]
    Assembly --> WeightCheck{Weight ≤ 60 kg}
    WeightCheck --> PerformanceTesting
    PerformanceTesting --> ConformanceCheck{Complies with IS 941}
    ConformanceCheck -- Yes --> ApprovedUnit
    ConformanceCheck -- No --> ReworkReject

Key Testing Procedures under IS 941

1. General Testing (Clause 10.1):

• Each firefighting blower or exhauster must be tested to confirm adherence to the standard’s material, performance, and safety requirements.

2. Air Delivery Test (Clause 5.1.3):

• The cylindrical airflow path is segmented into equal square zones along the diameter D.
• Measurements are taken at the center of each zone using an anemometer.
• The number of measurement points n is approximately the ratio D divided by the anemometer vane diameter d.

3. Material Verification (Clause 3.1 & Table 1):

Air Delivery Test Setup Illustration

flowchart LR
    AirwayDiameter[D: Airway Cylinder Diameter]
    Segmentation[Divide into square zones (D/d)]
    Measurement[Place anemometer vane center in each zone]
    VelocityTest[Measure air velocity at each point]
    AirwayDiameter --> Segmentation --> Measurement --> VelocityTest

Marking and Labelling Requirements (IS 941)

• Clause 9.1.1 states that products may bear the Standard Mark indicating conformity.
• Clause 9.1.2 specifies that use of the Standard Mark is governed under the Bureau of Indian Standards Act, 1986.
• Manufacturers must obtain a license from BIS to legally use the Standard Mark.

Important Highlights:

• The Standard Mark serves as a quality and conformity symbol.
• Licensing conditions and details are managed by the BIS.
• IS 941 does not provide explicit formulas or tables for marking but emphasizes compliance.

Summary Table

graph TD
    Manufacturer --> ApplyLicense[BIS License Application]
    ApplyLicense --> LicenseDecision{License Granted?}
    LicenseDecision -- Yes --> UseMark[Use Standard Mark]
    LicenseDecision -- No --> NoMark[No Marking Allowed]
    UseMark --> Market[Product Sold with BIS Mark]

Painting and Finishing Specifications (IS 941)

• Apply one coat of red oxide primer as the base layer.
• Follow with two coats of paint over the primer.
• Paint color specifications:
  • Stand body: Black.
  • Fire red: Shade number 536 according to IS 5-1978.
• Paints should conform to IS 2932-1974 for general engineering paint standards.

Summary Table

This scheme guarantees corrosion protection and consistent color coding for safety and identification.

graph TD
    SurfacePrep --> Primer[Apply Red Oxide Primer (1 coat)]
    Primer --> Paint1[Apply 1st Paint Coat (Black or Fire Red)]
    Paint1 --> Paint2[Apply 2nd Paint Coat (Black or Fire Red)]
    Paint2 --> FinishedSurface[Completed Protective Finish]

Requirements for Conformity under IS 941 (Clause 10)

• All firefighting blowers and exhausters must be tested to ensure compliance with the standard’s dimensions, materials, performance, and safety features.
• Use of the Standard Mark is regulated by the BIS Act of 1986, with licensing conditions provided by BIS.

Key Compliance Parameters

Flow Rate Formula for Verification

[ Q = A \times v ]

Where:

• (Q): Flow rate (liters per minute)
• (A): Cross-sectional area of the nozzle (cm²)
• (v): Velocity of water (cm/s)

Compliance Testing Flow

flowchart TD
    Start[Equipment Sample] --> DimCheck{Dimension Check}
    DimCheck -- Pass --> MaterialCheck{Material Quality}
    DimCheck -- Fail --> Reject[Reject Sample]
    MaterialCheck -- Pass --> PerformanceTests{Performance Testing}
    MaterialCheck -- Fail --> Reject
    PerformanceTests -- Pass --> SafetyCheck{Safety Compliance}
    PerformanceTests -- Fail --> Reject
    SafetyCheck -- Pass --> Conformity[Conformity Certified]
    SafetyCheck -- Fail --> Reject

Packaging and Handling Requirements per IS 941

• The petrol engine (2.5 kW with a 3-litre fuel tank) must be securely mounted within a frame equipped with lifting handles to facilitate safe handling.

• Materials for packaging:

  • Frame: Mild steel tubes conforming to IS 1239 (Part 1):1979.
  • Wire fabric: Welded steel wire mesh as specified in IS 4948:1974.
  • Protective cover: Cotton canvas meeting second revision specifications.

• Handling considerations:

  • The frame design must support lifting and transportation without damage.
  • Packaging should protect the engine from mechanical shocks and environmental exposure during transit.

• Compliance verification:

  • Clause 10.1 requires inspection of packaging and handling according to the standard.

Typical Packaging Frame Specification

Handling Procedure

• Utilize the frame lifting handles.
• Avoid impact directly on the petrol tank.
• Ensure secure fastening to prevent movement within packaging.

flowchart LR
    EngineWithTank --> FrameWithHandles
    FrameWithHandles --> WireFabricProtection
    WireFabricProtection --> CanvasCover
    CanvasCover --> SafeTransport

Summary of Annexures and Notes in IS 941

1. Material Specifications (Clause 3.1, Table 1):

2. Engine Options (Amendment No. 2, March 1993):

• Petrol engine of 2.5 kW with a 3-litre tank (IS 7347:1974).
• Lightweight diesel engine rated 3.23 kW (IS 10001:1981).
• Electric motor alternative: 3-phase induction motor, 2.2 kW (IS 325:1978), optionally flameproof (IS 2148:1981).

3. Notes on Electric Supply (Clause 2.2):

• Where electricity is available, the petrol engine may be replaced by a 3-phase induction motor of 2.2 kW.
• Flameproof motor enclosures are recommended for hazardous locations.

4. Conformity Criteria (Clause 10.1):

• All equipment must meet material and performance requirements.
• Testing and inspection are necessary for certification.

Visual Summary: Material and Power Components

graph TD
    BlowerExhausterComponents --> Impeller[Impeller: Aluminium Grade 4423]
    BlowerExhausterComponents --> Casing[Casing: Aluminium Grade 4423]
    BlowerExhausterComponents --> SuctionMouth[Suction Mouth: Aluminium Grade 4423]
    BlowerExhausterComponents --> ExhaustPipe[Exhaust Pipe: Canvas]
    BlowerExhausterComponents --> Frame[Frame: Mild Steel Pipe]
    BlowerExhausterComponents --> WireFabric[Wire Fabric: Steel]
    BlowerExhausterComponents --> EngineOptions[Engine Options: Petrol, Diesel, or Electric Motor]