Specification - hand-operated sirens
1985 Edition

Overview of Scope (Clause 1.1)

This section defines the specifications applicable to hand-operated sirens primarily used in firefighting, emergency scenarios, and environments where electrical sirens cannot be employed.

Essential Requirements:

• Protective Covers (Clause 4.2):
  • Covers must fully encase both the siren and the floor stand, including adjustment bolts at their maximum extension.
  • Stitching on waterproof covers should be uniform and intact.

Material Standards:

• Aluminium and aluminium alloy castings for engineering applications.
• Carbon and carbon-manganese free-cutting steels.
• Grey cast iron.
• Standard quality structural steel.
• Mechanical engineering steel tubing.
• Mild steel wire.
• Cotton canvas for protective covers.

Key Mechanical Formula (Clause 2.1.1):

[ \text{Torque} = M \times g \times R \quad \text{(Newton-meters)} ] Where:

• (M): mass in kilograms
• (g = 9.81, m/s^2): gravitational acceleration
• (R): radius of pulley in meters

Acoustic Power Calculation (Appendix A):

[ L_p = L_{ref} + L_{siren} - L_{ref-source} ]

Where:

• (L_p): siren acoustic power level (dB)
• (L_{ref}): reference source acoustic power (dB)
• (L_{siren}): siren sound pressure level (dB)
• (L_{ref-source}): reference source sound pressure level (dB)

SI Units Used:

For detailed clause-specific tables or formulas, please specify the requirement.

Breakdown of Siren Parts (Clause 2.1 & Figure 1)

• Siren Assembly: Includes the rotating disc and the operating handle.
• Portable Floor Stand: Features height adjustment bolts for ergonomic use.
• Control Handle: Facilitates the warbling tone by sliding the disc.
• Fixing Bolts: Secure the siren to the stand and adjust height.
• Protective Cover: Waterproof, fully enveloping siren and stand at maximum height as per Clause 4.2.

Material Considerations:

• Aluminium and its alloys (engineering grade)
• Carbon and carbon-manganese free-cutting steels
• Grey iron castings
• Ordinary structural steel
• Steel tubes suitable for mechanical engineering
• Mild steel wire
• Cotton canvas for the cover

Acoustic Power Relation (Clause A.1.3):

[ L_{W(siren)} = L_{W(ref)} + L_{p(siren)} - L_{p(ref)} ]

Where:

• (L_{W(siren)}): siren's acoustic power level (dB)
• (L_{W(ref)}): reference source acoustic power level (dB)
• (L_{p(siren)}): siren sound pressure level (dB)
• (L_{p(ref)}): reference source sound pressure level (dB)

graph LR
  SirenBody[Siren Body] --> Disc[Disc]
  SirenBody --> Handle[Handle]
  PortableStand[Portable Stand] --> HeightBolts[Height Adjusting Bolts]
  FixingBolt[Fixing Bolt] --> SirenBody
  WaterproofCover[Waterproof Cover] --> SirenBody
  WaterproofCover --> PortableStand

Refer to Clause 7.1 for detailed maintenance and spare parts information.

Fundamental Mechanical Relationships

1. Torque (Twisting Force) Calculation:

[ T = M g R ] Where:

• (M): mass (kg)
• (g = 9.81 m/s^2): gravitational acceleration
• (R): pulley radius (m)

2. Angle of Twist and Torque Relation:

[ T = \frac{\pi r^{4} \tau e}{2 l} ] Where:

• (\tau): shear modulus (N/m²)
• (r): radius of rod (m)
• (e): angle of twist (radians)
• (l): rod length (m)

Material Requirements

• Gears: Constructed from carbon steel per IS:4431-1978 or cast iron grade FG 200 as specified in IS:210-1978.
• Units: SI units (N, m, Pa, J) are consistently applied.

Reference SI Units Table

graph LR
Mass[M] --> Force[Force = M*g]
Force --> Radius[R]
Radius --> Torque[T = M*g*R]
RodDimensions[Rod radius r & length l] --> AngleTwist[Angle of Twist e]
Torque --> TorqueAngle[Torque related to e via T = (π r⁴ τ e)/2l]

Shape and Size Specifications (Clause 4.1 & Figure 1)

• The hand-operated siren and its floor-standing support must conform to the dimensions illustrated in Figure 1, with all measurements in millimeters.
• The waterproof cover must fully enclose the siren and floor stand, including the height adjustment bolts at their maximum extended position (Clause 4.2).

Additional Details:

• Cover color: Olive green as per IS 1424:1977, Variety No. 2.
• Materials: Aluminium, steel, and castings as per relevant IS standards.

Calibration Formula for Twisting Force (Clause 2.1.1):

[ \text{Twisting Force} = M g R \quad (N·m) ] Where:

• (M): mass (kg)
• (g = 9.81 m/s^2): acceleration due to gravity
• (R): pulley radius (m)

Rod twist expression:

[ T = \frac{7 \pi r^4 e}{2 L} ] Where:

• (7): rigidity coefficient (N/m²)
• (r): rod radius (m)
• (e): twist angle (radians)
• (L): rod length (m)

SI Units Recap:

• Force: Newton (N) = kg·m/s²
• Energy: Joule (J) = N·m
• Pressure/Stress: Pascal (Pa) = N/m²

graph TB
Siren[Siren] --> FloorStand[Floor Stand]
FloorStand --> HeightBolts[Height Adjusting Bolts]
HeightBolts --> Cover[Waterproof Cover (Olive Green)]
Cover --> FullCoverage[Complete Enclosure at Max Extension]

Acoustic Power Level Measurement (Clause A.1.3)

The acoustic power level (L_W) of the siren is determined by:

[ L_W = L_{W,ref} + L_{p,siren} - L_{p,ref} ] Where:

• (L_{W,ref}): reference source acoustic power (dB)
• (L_{p,siren}): siren sound pressure level (dB)
• (L_{p,ref}): reference source sound pressure level (dB)

Torque Limits (Clause 2.1.1 & Table B-2)

The torque required for siren operation is calculated as:

[ \text{Torque} = M g R \quad (N·m) ] Where:

• (M): mass in kg
• (g = 9.81 m/s^2)
• (R): pulley radius in meters

The relationship between torque and rod twist is:

[ T = \frac{G \pi r^4 e}{2 L} ] Where:

• (G): modulus of rigidity (N/m²)
• (r): rod radius (m)
• (e): angle of twist (radians)
• (L): length of rod (m)

Durability Requirements (Clause 4.2)

• The protective cover must fully enclose the siren and stand, including all adjustment bolts.
• Stitching on the waterproof cover must be continuous and uniform.

SI Units Summary

Quality of Workmanship (Clause 6.1)

• All forgings and castings must be sound without pits, blowholes, scales, or cracks.
• No repairs or fillings are allowed that conceal defects.
• Burrs and sharp edges should be removed or smoothly rounded.

Finish and Cover Specifications (Clauses 3.4 & 4.2)

• Covers must be olive green cotton canvas meeting IS 1424:1977 standards.
• Covers must provide complete enclosure of the siren and floor stand including height adjustment bolts.
• Stitching on the cover must be uniform, tight, and unbroken.

Torque Operating Limits (Clause 5.3)

• The torque to operate the siren at 60 ± 2 rpm must not exceed 1.5 Newton-meters (as tested per Appendix B).

Summary Table:

flowchart TD
  ForgingsCastings[Forgings & Castings] --> NoDefects[No defects, burrs removed]
  Cover[Waterproof Cover] --> Color[Olive green, IS 1424]
  Color --> FullCoverage[Complete coverage including bolts]
  FullCoverage --> Stitch[Even, unbroken stitches]
  SirenOperation[Siren Operation] --> TorqueLimit[Torque ≤ 1.5 N·m at 60 rpm]

Instruction Manual Requirements (Clause 7.1)

• Each siren must include an illustrated guide detailing:
  • Mounting the siren onto the floor stand.
  • Operating procedures and routine maintenance, including lubrication instructions.
  • A pictorial spare parts list with reference numbers for all consumable components.

Lubrication Marking (Clause 6.3)

• Lubrication points must be clearly labeled with "oil" or "grease" adjacent to the lubrication nipples.

Cover Requirements (Clause 4.2)

• The protective cover must fully enclose the siren and floor stand at maximum extension.
• Stitching on the cover must remain uniform and intact.

Calibration Formula (Clause 2.1.1)

[ \text{Torque} = M g R \quad (N·m) ] Where:

• (M): mass in kg
• (g = 9.81 m/s^2)
• (R): pulley radius in meters

flowchart LR
  SirenUnit[Siren Unit] --> LubricationPoints[Lubrication Points]
  LubricationPoints --> Marking{Marking Type}
  Marking -->|Oil| OilMark["Oil" label near nipple]
  Marking -->|Grease| GreaseMark["Grease" label near nipple]

ISI Certification Mark (Clause 8.1.1)

• Sirens can bear the ISI mark to indicate conformity with Indian Standards.
• This mark is a sign of quality assurance under strict inspection protocols.
• Usage of the ISI mark is regulated by the Indian Standards Institution Certification Marks Act.
• License details and permissions are obtainable from ISI authorities.

Lubrication Points Marking (Clause 6.3)

• Lubrication points must be clearly identified with the inscriptions "oil" or "grease" near the respective nipples.

Summary:

• ISI Mark ensures product compliance and quality.
• Clear labeling of lubrication points facilitates proper maintenance.
• No specific marking required on covers, but must comply with coverage requirements.

flowchart TD
  Siren[Sirens] --> Marking{Marking}
  Marking --> ISIMark[ISI Certification Mark]
  Marking --> LubricationMark[Lubrication Points marked "oil"/"grease"]
  ISIMark --> QualityAssurance[Compliance & Quality Assurance]
  LubricationMark --> MaintenanceEase[Ease of Maintenance]

Acoustic Power Measurement Method

The acoustic power level, (L_w), of the siren under evaluation is calculated as:

[ L_w = L_{w0} + L_{pm} - L_{p0} ] Where:

In terms of power (W):

[ 10 \log_{10} \frac{W}{W_0} = 10 \log_{10} \frac{W_0}{W_0} + 20 \log_{10} \frac{P_m}{P_0} - 20 \log_{10} \frac{P}{P_0} ]

Where:

• (W): acoustic power output of siren (W)
• (W_0 = 10^{-12}) W (reference power)
• (P_m): sound pressure level of siren
• (P_0): sound pressure level of reference source

Durability Requirements

• The average sound pressure level must be at least 118 dB (ref. 0.00002 N/m²).
• Testing is conducted in a semi-reverberant room of volume 127.5 m³ with approximately 2 seconds reverberation time or equivalent.

Summary Table

Experimental Setup (Clause B-1.1)

• A steel rod (A) is mounted on two ball bearings (B1, B2) fixed to stands (S1, S2).
• One end is connected to the siren; the opposite end has a handle (H).
• A semi-circular disc (D) is attached near the siren end with a spring-loaded pointer (P) at the handle end.
• Torque applied to the rod causes twisting, which deflects the pointer proportionally on the disc.

Calibration Procedure (Clause B-2.1)

• The handle (H) is replaced by a pulley of known radius (R).
• Torque is applied by suspending a mass (M) on a string over the pulley.
• Torque applied is:

[ \text{Torque} = M g R \quad (N·m) ] Where:

• (M): mass in kg
• (g = 9.81 m/s^2)
• (R): pulley radius in meters

Torque-Twist Angle Relation (Clause B-2.1.1)

[ M g R = \frac{\pi G r^4}{2 L} \theta ] Where:

• (G): modulus of rigidity (N/m²)
• (r): radius of the rod (m)
• (L): length of the rod (m)
• (\theta): twist angle (radians)

Units Summary

graph LR
  Rod[Steel Rod] -- Connected to --> Siren[Siren]
  Rod -- Supported by --> Bearing1[Ball Bearing 1]
  Rod -- Supported by --> Bearing2[Ball Bearing 2]
  Rod -- Handle End --> Handle[Handle or Pulley]
  Disc[Semi-circular Disc] -- Pointer --> Pointer[Pointer]
  Handle -- Rotation causes --> Twist[Torsion in Rod]
  Twist -- Causes --> PointerDeflection[Pointer Deflection]