Transformers & Switchyards
High velocity water spray, with drainage and separation designed in.
At a glance
- Hazard family
- Electrical & process
- Protected by
- Water spray, Hydrant, Water curtain
- Designed to
- NFPA 15, IS 2189
- Water spray on the transformer
- 10.2 L/min/m² of the projected surface
Design basis
- Water spray on the transformer
- 10.2 L/min/m² of the projected surfaceNFPA 15
- Water spray on the ground around it
- 6.1 L/min/m² of non-absorbing groundNFPA 15
- Minimum nozzle pressure
- 1.4 bar (20 psi), unless listed for lessNFPA 15
Standards that apply
- NFPA 15Water spray fixed systems for fire protection.
- IS 2189Automatic fire detection and alarm systems.
The risk
A power transformer holds tens of thousands of litres of insulating oil. An internal fault can arc, rupture the tank and release burning oil around it, and a bushing failure can start a fire at the top. The fire spreads to neighbouring transformers unless they are separated.
The cost is measured in outage as much as in equipment: a large transformer can take many months to replace.
The scheme
Extinguish the oil fire, drain it away and stop it spreading:
- High velocity water spray around the transformer, released by heat detection, to emulsify and extinguish burning oil.
- A soak pit filled with gravel under the transformer, so burning oil drains away and is smothered.
- Fire walls or water curtains between transformers.
- Hydrants within reach of the yard.
Systems that apply
NFPA 15Fire Water Spray System
Medium and high velocity spray for vessels, transformers and process equipment.
NFPA 24Fire Hydrant System
Plant-wide ring main, hydrants, monitors and hose boxes, sized to the site.
NFPA 15Water Curtain System
Separation and exposure protection where spacing alone is not enough.
Products used
Deluge Valves & Systems · 9
Deluge Valve Cast Carbon Steel (Model PD-CS)
Cast carbon steel, 80 to 200 mm, 250 psi
Deluge Valve Cast Stainless Steel (Model PD-SS)
Cast stainless steel, 80 to 200 mm, 250 psi
Deluge Valve Aluminium Bronze (Model PD-AB)
Aluminium bronze, 80 to 200 mm, 250 psi
Deluge Valve Skid Cabinet
Pre-assembled and factory tested, with bypass
Deluge Valve Cast Carbon Steel (Model PD-ILV)
Inline globe pattern, cast carbon steel
Deluge Valve Aluminium Bronze (Model PD-ILVAB)
Inline globe pattern, aluminium bronze
Deluge Valve Cast Stainless Steel (Model PD-ILVS)
Inline globe pattern, cast stainless steel
Deluge Valve
Dry pilot, wet pilot and electric release
Wet Pilot Inline Deluge Assembly (Stainless Steel)
PD-ILVS with wet pilot trim, 80 to 200 mm
Spray Nozzles · 3
MVWS Nozzle Stainless Steel
Stainless steel 316, K-18 to K-102, 65° to 160°
MVWS Nozzle Brass
Brass, K-18 to K-102, 65° to 160°
MVWS Nozzle
Brass or stainless steel 316, K-18 to K-102
Strainers · 6
Fabricated Duplex Strainer
Twin baskets, cleaned without shutting down
Fabricated Basket Strainer
Top-removal basket, 2" to 24"
Fabricated Y Strainer
1" to 24", ASME Class 150 to 2500
Fabricated Tee Strainer
Graded filtration, 2" to 24", ASME 150 to 600
Fabricated Inline Strainer
Inline, 15 to 150 mm, 40 to 100 mesh
Strainer
Y-type, 1" to 24", threaded, socket weld or flanged
Questions we are asked
Why high velocity water spray on a transformer?
High velocity droplets break up and emulsify the burning oil surface, which puts the fire out rather than only cooling the tank.
What is the soak pit for?
It drains burning oil away from the transformer into gravel, where it is smothered, so it cannot pool and keep the fire going.
Is spray enough between transformers?
Fire walls or water curtains are also used to stop a fire spreading from one unit to the next.
Related hazards
Projects on this hazard
- Photography to followTata Cummins
High velocity water spray system — Tata Cummins
High velocity water spray (HVWS) system for Tata Cummins at Jamshedpur. · Jamshedpur
- Photography to followTata Steel
Medium velocity water spray system — Tata Steel
Medium velocity water spray (MVWS) system for Tata Steel at Joda Mine. · Joda Mine
- Photography to followGAIL
Hydrant system — GAIL
Fire hydrant system for GAIL at Vijaipur. · Vijaipur
- Photography to followTISCO
Hydrant system — TISCO
Fire hydrant system for TISCO at Noamundi. · Noamundi
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