Cable Galleries / Trenches
Linear heat detection with water spray or clean agent.
At a glance
- Hazard family
- Electrical & process
- Protected by
- Water spray, Clean agent, Fire alarm, CO₂
- Designed to
- NFPA 15, NFPA 12, NFPA 2001, NFPA 72
- Water spray on cable trays
- 12.2 L/min/m²
Design basis
- Water spray on cable trays
- 12.2 L/min/m²NFPA 15
- CO₂, deep-seated fire (dry electrical)
- 50% design concentration, within 7 minutesNFPA 12
- Clean agent hold time
- At least 10 minutesNFPA 2001
Standards that apply
- NFPA 15Water spray fixed systems for fire protection.
- NFPA 12Carbon dioxide extinguishing systems.
- NFPA 2001Clean agent fire extinguishing systems.
- NFPA 72Fire alarm and signalling.
The risk
A cable gallery is a long run of fuel: every metre of cable insulation burns, and a fire travels along the trays faster than people can follow it in a confined, smoke-filled space.
The damage outlasts the fire. Power and control cables for a whole plant can run through one gallery, and losing them stops the plant.
The scheme
Detect along the whole run and suppress where the cables are:
- Linear heat detection cable along the trays, locating a fire to its zone.
- Water spray onto the trays, or clean agent or CO₂ where the gallery is enclosed and normally unoccupied.
- Fire stops at walls and floors to keep the fire in its section.
- Detection and alarm linked to the control room, with access for firefighting at each section.
Systems that apply
NFPA 15Fire Water Spray System
Medium and high velocity spray for vessels, transformers and process equipment.
NFPA 2001Clean Agent Fire Suppression
Gaseous suppression for control rooms, server rooms and cable galleries.
NFPA 72Fire Detection & Alarm System
Detection and alarm, supplied and integrated under the same contract as the suppression system.
NFPA 12CO₂ Fire Suppression System
Total flooding carbon dioxide for unoccupied electrical and machinery spaces.
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
Water spray or gas for a cable gallery?
Water spray suits galleries that are open or large; clean agent or CO₂ suits galleries that can be sealed and are normally unoccupied.
How is a fire found in a long gallery?
Linear heat detection cable along the trays senses heat over its whole length and locates the fire to a zone.
Why fit fire stops?
A cable fire travels along the trays; fire stops at walls and floors keep it in one section.
Related hazards
Projects on this hazard
- Photography to followTata Memorial Hospital
Fire detection and alarm system — Tata Memorial Hospital
Fire detection and alarm system for Tata Memorial Hospital at Jamshedpur (JUSCO). · Jamshedpur (JUSCO)
- 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
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