1. Scope — Which Facilities Must Comply with OISD-117
OISD-STD-117 covers Fire Protection Facilities for Petroleum Depots, Terminals, Caverns, CTF (Central Tank Farms), Pipeline Installations, and Lube Oil Installations. If your facility stores, receives, or dispatches Class A, B, or C petroleum products — including crude oil, refined products, or lube oil — your emergency siren system falls under this standard.
Note that OISD-STD-117 is a different standard from OISD-STD-116, which covers petroleum refineries and oil/gas processing plants. Ensure you are referencing the correct standard for your facility type before your next audit.
The Errata-01 dated 11.01.2021 for emergency siren codes has been superseded by an Updation issued by OISD that revised the guidelines on Emergency Siren Codes in clause 5.1.(vi). Always verify you are referencing the current edition. When in doubt, confirm with your competent authority or the OISD portal at oisd.gov.in.
2. Emergency Classification — Level I, II, III
OISD-117 classifies emergencies into three levels based on seriousness and the response resources required. Your siren system and control panel must be capable of declaring all three levels distinctly.
Site-Contained Emergency
Can be managed within the installation using on-site resources. No impact beyond the site boundary. Declare using FIRE siren code.
Mutual Aid Required
Beyond on-site resources; requires mutual aid from neighbouring industries or local emergency services. Wider impact possible.
Disaster — External Response
Major disaster requiring state/national agency involvement. Significant impact beyond the site. Declare using DISASTER siren code.
3. OISD-117 Emergency Siren Codes — Exact Patterns
Your siren control panel must be programmed with these exact codes. These are the mandatory patterns under OISD-STD-117. No other tones should be used for these emergency declarations — using a non-compliant pattern will fail an audit.
| Condition | Siren Pattern | Duration / Sequence |
|---|---|---|
| FIRE Level I | Wailing sound | 2 minutes continuous wailing Activate immediately on confirmed fire |
| DISASTER Level II / III | Wailing sound, repeated | Wailing 2 min → gap 10 sec → Wailing 2 min → gap 10 sec → Wailing 2 min Total duration approx. 6 min 20 sec |
| ALL CLEAR Termination | Straight run (steady) | 2 minutes continuous steady tone Sounded only when emergency is fully resolved |
| TEST SIREN Weekly | Straight run (steady) | 2 minutes continuous steady tone Must be conducted at minimum once per week |
The weekly test siren uses a straight run (steady tone) — the same pattern as All Clear. This is intentional and mandatory. If your facility uses a wailing tone for the weekly test, workers cannot distinguish a test from a real fire emergency. This is a common compliance failure and a documented cause of delayed emergency response. Reprogram your panel immediately if you are using wailing for the test siren.
Facilities under PNGRB (Petroleum and Natural Gas Regulatory Board) jurisdiction also follow ERDMP siren codes, which align closely with OISD-117 but define Level I / Level II / Level III sequences with slightly different gap timings. Confirm which regulatory body has jurisdiction over your facility and programme your panel accordingly. Our Advanced Siren Control Panel supports configurable siren codes for both OISD-117 and ERDMP patterns.
4. Siren Location and Coverage Requirements
Clause 14.2.5 of OISD-STD-117 specifies the following requirements for siren placement and coverage:
- Emergency sirens shall be located suitably to cover the whole area of the installation — no part of the facility should be in an acoustic dead zone
- The operational control (the panel with activation buttons) shall be located within the installation at a safe, identifiable, and easily accessible location
- Electric fire sirens shall be installed at a suitable elevated location, with the operating switch positioned near the risk area
- Hand operated sirens (IS-6026 compliant) shall be provided at strategic locations and clearly marked — these serve as mandatory backup for power failure scenarios
Location Best Practice from Field Experience
OISD-117 mandates that the entire facility is covered but does not specify dB minimums explicitly. From our experience across 4500+ installations at oil and gas facilities, the practical minimum is 10 dB above ambient noise at the farthest occupied point within the boundary. For most petroleum terminals, this requires a minimum 5 km rated motor siren at 6–10 m mounting height. Larger facilities with high ambient noise (pumping stations, compressor areas) often require multiple sirens positioned at opposite ends of the site.
5. Control Panel Requirements
The siren control panel is the most critical component for OISD compliance. It must meet the following requirements under OISD-STD-117:
Mandatory Panel Functions
- Dedicated button per emergency level — separate clearly labelled buttons for FIRE, DISASTER, ALL CLEAR, and TEST SIREN. No shared or combined buttons
- Auto-timing of siren sequences — the panel must automatically complete the programmed code sequence without the operator holding the button. Manual hold is not compliant
- Manual override — the ability to stop a siren sequence and activate any code directly, independent of the automated sequence
- Battery backup — the panel must operate on backup power during mains power failure for a minimum duration sufficient to complete at least one full siren sequence
- LCD or indicator display — operational mode must be clearly visible at the panel at all times
- Potential-free contacts for remote activation — required for integration with fire alarm panels, DCS, and SCADA systems
Physical Requirements
- Panel housing in weatherproof sheet metal enclosure — fire red colour recommended for high visibility
- Located in continuously manned area (control room, fire station, or security post)
- Key-locked programming to prevent unauthorised schedule changes
- Panel must be labelled with the OISD siren code chart clearly visible nearby
6. Integration with Fire Panel, DCS, and SCADA
OISD-117 requires that the emergency siren system accepts automatic activation inputs from the fire detection system. The siren should not rely solely on a human operator to sound the alarm — automatic actuation is mandatory for confirmed fire alarm conditions.
Required Integration Points
- Fire alarm panel — potential-free contact output from the fire panel triggers the FIRE siren code automatically on confirmed alarm
- Gas detection system — confirmed gas release (above LEL threshold) triggers DISASTER code
- ESD (Emergency Shutdown) system — ESD activation can be configured to auto-trigger the appropriate siren code level
- DCS / PLC / SCADA — potential-free contact input from any DCS or PLC output permits remote automated siren activation from the control room
All potential-free contact inputs to the siren panel must be volt-free (dry contact, NO or NC as specified). Confirm contact rating with your siren panel supplier — our Advanced Siren Control Panel accepts 24V DC and 230V AC dry contact inputs. Do not connect live voltage directly to the contact input terminals.
7. Testing and Maintenance Schedule
OISD-117 is explicit on testing frequency. Non-compliance on this single point is one of the most common audit failures we see — many facilities either skip the weekly test or conduct it without documenting the results.
Mandatory Testing Requirements
| Test Type | Frequency | Code Used | Documentation Required |
|---|---|---|---|
| Operational test (all zones) | Minimum once per week | Straight run — 2 minutes | Yes — logbook entry with date, time, result, and operator signature |
| Full emergency mock drill | Minimum quarterly (or as per ERDMP) | Full siren code sequence including FIRE / DISASTER / ALL CLEAR | Yes — drill report with participation rate, response time, and corrective actions |
| Backup power test | Minimum every 6 months | Mains isolate — confirm siren fires on battery backup | Yes — record battery voltage before and after test |
| Siren audibility check | Minimum annually | Straight run | Sound level measurement at defined test points — document dB(A) readings |
OISD auditors routinely check the siren test logbook and ask for the last 3 months of weekly test entries. A missing entry is treated as a missed test. Ensure your logbook is physically maintained at the siren control panel, not in the HSE office. Digital records are acceptable only if they can be produced on-site during an audit.
8. Complete OISD-117 Siren Compliance Checklist
Use this checklist during internal audits or before a statutory OISD inspection. Each item maps to specific requirements under OISD-STD-117.
Siren Installation
Electric fire siren installed at elevated location, audible across entire facility boundary
Confirm by sound level measurement at all four corners of the site during peak production noise.
Hand operated siren (IS-6026) installed at strategic locations and clearly marked
Minimum one at each gate/entry point and near the tank farm.
Siren mounting height sufficient to clear surrounding obstructions
Recommended minimum 6 m above the highest nearby structure within 50 m.
Siren housing weatherproof and suitable for outdoor installation
IP55 minimum for motor sirens in outdoor locations.
Control Panel
Panel located in continuously manned area (control room / fire station)
Separate labelled buttons for FIRE, DISASTER, ALL CLEAR, and TEST SIREN
Labels must match the OISD siren code chart posted on or near the panel.
Siren sequences auto-complete on button press — operator does not need to hold button
Manual override available independent of automated sequence
Battery backup in place and tested within last 6 months
Battery must support at least one complete siren sequence.
OISD siren code chart posted at panel, at all entry gates, and at muster points
Siren Codes Programmed Correctly
FIRE code: wailing sound, 2 minutes continuous
DISASTER code: wailing 2 min → 10 sec gap → wailing 2 min → 10 sec gap → wailing 2 min
ALL CLEAR code: straight run, 2 minutes
TEST SIREN code: straight run, 2 minutes (NOT wailing)
Integration
Fire alarm panel wired to siren panel via potential-free contact for automatic activation on FIRE code
Gas detection system wired to trigger DISASTER code on confirmed gas release
DCS / SCADA integration verified with test activation from control room
Testing and Documentation
Weekly siren test conducted and logged — last 13 weeks of logbook entries available on-site
Quarterly mock drill completed with full code sequence and documented drill report
Annual audibility check — dB(A) measurements at defined test points documented
Backup power test completed within last 6 months — battery voltage documented
Worker Training
All workers trained on siren codes during induction
Training record with individual sign-off maintained.
Annual refresher training completed — workers can correctly identify all four siren codes
Contractor and visitor siren code briefing given at gate before entry
Siren code chart displayed in all languages spoken by workers at this facility
9. Audit Preparation — What OISD Inspectors Check
Based on our experience supporting OISD compliance audits across 4500+ installations, the following are the most frequently raised non-conformances specifically related to the siren system:
- Missing or incomplete test siren logbook — this is the single most common finding. The logbook must be physically present at the panel, not in an office or digital system only.
- Wrong code for test siren — facilities using wailing for the weekly test instead of straight run are immediately flagged.
- Siren not audible in all areas — auditors typically walk to the most distant point and the noisiest production area. If the siren cannot be heard over machine noise, it is a non-conformance regardless of the technical rating on the siren.
- No hand operated siren or it is not clearly marked — the IS-6026 hand siren is explicitly required by OISD-117 as a backup. Many sites have them stored in a storeroom rather than mounted and marked at strategic locations.
- No automatic integration with fire panel — manual-only siren systems that have no automatic trigger from the fire alarm panel are non-compliant. The integration must be tested and demonstrated.
- Siren code chart not posted at entry gates and muster points — posting it only at the control panel is insufficient.
- Battery backup not tested or not present — many facilities have backup provision on paper but no tested battery in the panel.
At least 30 days before a statutory audit, conduct a full internal mock drill using the complete OISD siren code sequence. Measure dB(A) at your four facility boundary corners during peak production. Document everything. Any gaps identified in this internal trial can be corrected before the statutory team arrives. We offer engineering reviews for existing installations — share your site layout and current siren specifications and we will advise on gaps.
Need an OISD-117 Compliant Siren System?
We have designed and supplied siren control systems for refineries, petroleum terminals, and pipeline installations across India for 16+ years. Our Advanced Siren Control Panel is pre-configured for OISD-117 and ERDMP siren codes.
