Petrochem + LPG Industrial HVAC — OISD-STD + PESO + NFPA 30 + IEC 60079 Pressurisation Framework
Indian petrochem + LPG installations must meet the full OISD-STD + PESO + NFPA 30 + IEC 60079 stack. Control room HVAC sits behind Type Y barrier at +25 Pa with continuous pressurisation; analyzer shelters at Class 1 Div 2 (Zone 2) need EX-rated AHU + every cable gland EX-listed; gas detection at 25 % LEL must auto-shut HVAC + initiate purge. Mid-size petrochem control + analyzer scope runs ₹160 lakh. Three failures OISD/PESO inspectors catch: single-AHU pressurisation losing barrier during PM, analyzer shelter EX-rated with non-EX cable glands, gas-detection alarming to DCS without auto-shutdown interlock.
Petrochem + LPG industrial — the Indian regulatory stack
India petrochemical (RIL Jamnagar, IOCL Panipat, BPCL Kochi, HPCL Mahul) + LPG (HPCL bottling, IOCL Jasidih, BPCL Cherlapalli) + chemical (UPL, Pidilite, Aarti, BASF India) installations face the most stringent fire+gas regulator stack in Indian engineering — OISD-STD codes (Oil Industry Safety Directorate), PNGRB Regulations, PESO Petroleum Rules 2002, Factories Act 1948, Chemical Accident Rules 1996, IS/IEC 60079, NFPA 30, NFPA 11, API 521. Hazardous-area HVAC must combine pressurisation, purge cycles, gas-detection interlock, and intrinsically-safe design.
Petrochem control room + analyzer shelter HVAC scope
| Space | Hazardous classification | Pressurisation | Gas detection | HVAC requirement |
|---|---|---|---|---|
| Main control room (DCS + ESD) | Non-hazardous (Type Y barrier) | +50 Pa positive | OA intake + room | EX e or non-Ex per IEC 60079; 50 Pa for Type Z |
| Marshalling cabinet room | Type Z barrier | +25 Pa positive | OA intake | HVAC w/ 100 % OA + filtered |
| Analyzer shelter (field) | Class 1 Div 2 (Zone 2) | +25 Pa or Type Y purge | sample H2S + LEL | EX-rated AHU + ducting + gas tight |
| Switchgear room (HV) | Non-hazardous | — | — | dust + temp control |
| MCC room | Non-hazardous (segregated) | +10 Pa | — | dust control + 12 ACH |
| Battery room (lead-acid) | — | — | H2 detection | 12 ACH continuous; spark-resistant fan |
| DG room (CPCB IV+) | — | — | CO + diesel mist | as per IS 9818 |
| LPG cylinder shed | Class 1 Div 1 | — | LPG detection | natural ventilation; no electrical |
| Pump house (volatile) | Class 1 Div 2 | — | LEL | EX-rated lighting + motors |
| Tank gauge cabinets | Class 1 Div 2 | — | — | EX rated |
Three petrochem HVAC failures OISD/PESO inspectors catch
- Control room pressurisation lost during AHU service — Type Y barrier needs continuous pressurisation per OISD-STD-163 + IEC 60079-13. AHU maintenance window must NOT depressurise the room — design with 2x AHU + auto-changeover. Indian sites routinely have single AHU + 24-hr loss-of-pressurisation during PM = barrier failure.
- Analyzer shelter EX-rated but cable glands non-EX — full barrier integrity needs every penetration EX-rated. Glands + sealing compounds + duct couplers — all must be Ex-d or Ex-e listed. PESO + OISD will inspect this individually. Single non-EX gland fails the entire shelter classification.
- Gas-detection interlock to HVAC missing — H2S or LEL alarm at 25 % must auto-stop HVAC + initiate purge. NFPA 86 + OISD-STD-163 require this. Many Indian designs alarm to DCS only without auto-shutdown — fails OISD safety audit.
- OISD-STD-163 — Process Control Rooms + Buildings Safety, Oil Industry Safety Directorate, India.
- OISD-STD-189 — Standard on Fire Protection at Marketing Locations.
- OISD-STD-118 — Layouts of Oil + Gas Installations.
- NFPA 30:2024 — Flammable + Combustible Liquids Code.
- NFPA 11:2024 — Standard for Low- Medium- + High-Expansion Foam.
- API 521:2020 — Pressure-relieving + Depressuring Systems.
- IEC 60079 series — Explosive Atmospheres (Part 0 General + Part 13 Pressurisation + Part 14 Inspection).
- The Petroleum Rules 2002 (India PESO) + Petroleum + Natural Gas Regulatory Board Regulations.
- Chemical Accidents (Emergency Planning Preparedness + Response) Rules 1996 (India MoEF).