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Engineering Reference

Industrial Siren Engineering Guide

A practical technical reference for HSE engineers, project consultants, and plant managers designing industrial emergency warning systems.

Coverage CalculationZone MappingERDMP CodesOISD-117 Compliance
Coverage
Calculated at 1.5× site diagonal
Ambient noise
Siren must exceed by 10+ dB
Mounting ht
Minimum 6 metres recommended
Wind effect
Downwind +25%, upwind −40%
OISD codes
FIRE / DISASTER / ALL CLEAR / TEST
Test tone
Straight-run only — never wailing
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Industrial Siren Engineering Guide OISD-117 ERDMP

Coverage Calculation

The standard coverage calculation uses 1.5× the site diagonal as the required siren range. For ambient noise above 85 dB, the siren output at the furthest point must still exceed ambient by at least 10 dB.

RuleValue
Design range1.5× site diagonal
Min. dB above ambient10 dB at furthest point
Mounting heightMinimum 6 metres
Wind factor downwind+25% effective range
Wind factor upwind−40% effective range
Safety marginAdd one model size above calculated

OISD-117 Tone Codes

EventToneDuration
Fire alarmWailing — continuousUntil cancelled
Disaster / evacuationWailing — 3 bursts3 × 15 seconds
All clearSteady — continuous30 seconds
TestSteady — 1 burst15 seconds
Shift changeSteady — continuous30 seconds

ERDMP requirement: Petroleum facilities under ERDMP must implement OISD-117 tone codes and test the siren system on a documented schedule. We supply the compliance documentation with every system.

Motor Siren vs Electronic Siren — Quick Reference

CriterionMotor SirenElectronic Siren
Coverage range0.5–16 km50m–1.5 km
Output112–126 dB90–110 dB
Power supply230V or 415V AC12V DC to 230V AC
Tone flexibility2 tones (wailing + straight)128+ selectable tones
MountingTower or roof — 6m+ heightWall or pole
Best forOutdoor, large area, emergencyIndoor, multi-zone, multi-tone

Read full comparison guide →

Full Guide
Motor Siren vs Electronic Siren — The Real Difference
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