Home » Introduction » Deluge Water Spray System

Deluge Water Spray System

1. Deluge Water Spray System:

  • An automated water spray system where the water distribution piping is equipped with open spray nozzles for discharging over a protection area or equipment.
  • Deluge water Spray systems designed according to NFPA 15, API 2030, IP 19 guidelines and local regulations.
  • The main objectives are any one or combination of the following :
    • Extinguishment of fire
    • Control of burning
    • Exposure protection
    • Prevention of fire




Typical Application rates for Deluge Water Spray System: (API 2030):

Typical Application rates for Deluge Water Spray System

2. Factors determining the requirement of Deluge Water Spray System:

  • Spray System for Process Pumps:
    • When pumps handle hydrocarbon liquids (flammable or combustible) at temperatures above its flash point.
    • Located Close to equipment that can be quickly damaged by pump fire.
    • Where protection of pumps is impractical by monitors/hydrants and potential of fire escalation is possible.
  • Spray System for Pipe racks:
    • To be evaluated based on potential of pool fires or severe exposures below the pipe rack.
  • Spray System for Vessels & Columns :
    • High pressure vessels (>10 barg) handling flammable / combustible liquids with inventory above 5 tons and also based on project philosophy.
    • Vessels handling flammable / combustible liquids and located in a congested area.
  • Spray System (cooling) for Atmospheric Storage Tanks:
    • API 2001 recommends protection of the portion of shell and roof not in contact with the liquid content of tank. (@4.1 lpm/m2)
    • Sectionalization of the spray rings should be done for optimization of water quantity.

 




Deluge Skid Installation

 

 

Example of a Water Spray System Installation

Example of a Water Spray System Installation


Fig: Example of a Water Spray System Installation

3. Type of Deluge Valves:

  • Type of Deluge Valves (based on operation):
    • Complete On/off deluge Valve: These are deluge valves which open fully upon activation and closed fully upon resetting.
    • Variable Pressure Control Deluge Valve: Preset constant Valve downstream side pressure is maintained irrespective of the upstream pressure.
  • Type of Activation of Deluge Valves :
    • Hydraulic Activation : By means of hydraulic Quartzoid bulb detection
    • Electrical Activation : By means of F&G detection system
    • Electro-Pneumatic Activation : By means of pneumatic Quartzoid bulb and/or F&G detection system
Deluge Valve (Body)

Deluge Valve (Body)




Internal Deluge Valve Construction

Internal Deluge Valve Construction

4. Deluge valve – Principle of Operation:

  • Area of upper chamber of DV is twice that of the lower chamber
  • Force in Upper Chamber = Pressure x 2 Area
  • Force in Lower Chamber = Pressure x Area
  • Pressure is same on both sides.
  • Force in upper chamber is more than that of the lower chamber
Electric & Pneumatic Release Trim

Electric & Pneumatic Release Trim

Operation of Variable Pressure Control type - Deluge valve

Operation of Variable Pressure Control type – Deluge valve

5. Deluge Valve & By-Pass Valves & Location:

  • Deluge valves are always 15 meter away from the protected equipment and any other process equipment. (from pipe racks at least 6 m preferred where 15 not possible)
  • Manual by-pass valves shall be located opposite side or tapped from another part of the ring main.
  • Manual valve shall be 30 meter from the protected equipment.
  • Both valves shall be upstream of the wind direction preferably.
By Pass Valves & Deluge Valve Location

By Pass Valves & Deluge Valve Location

 

Typical Deluge Skid Installation

Typical Deluge Skid Installation

6. Deluge Skid Specifications/ Requirements:

  • The type of Deluge Valve mounting (ie vertical or horizontal).
  • Vertical mounting are more space saving
  • Where ambient temperature is of concern, the skids shall be inside enclosures and shall be provided with a heater to maintain the temperature at above 5 deg.C
  • All components should be within the enclosure
    • Space for deluge Skids to be indicated in the plot plan for the required size at early stages of the plot plan development.
    • Deluge Skids shall be at least 2 meter away from the road edges.
    • Electrical Heat Tracing of water filled pipe lines up to the deluge valve is required in freezing climatic conditions.
  • All components shall be listed/ approved type.
  • Specify vendor limits clearly in the P&I Ds.

7. Water Spray Nozzles:

  • An open water discharge device that, when discharging water under pressure, will distribute the water in a specific, directional pattern.
  • Types of water spray Nozzles :
    • Medium Velocity – Used for vessels, pumps, cable galleries, etc.
    • High Velocity – Used for Transformer spray system.
    • Pressure required for MV Nozzles 1.4 bar(g) and for HV nozzles about 3.4 barg for optimum performance.
  • Minimum Pipe Sizes in Deluge Systems (as per NFPA 15) is 1”.

8. Piping Requirements for Deluge System:

  • Piping Requirements as per NFPA :
    • 40, Carbon Steel (Galvanized) up to 8”
    • 30, Carbon Steel (Galvanized) 8” & above
  • Piping Installation requirements :
    • Suitable slope in the dry section of pipe
    • Provide Low point drain at suitable location
  • Pipe Velocity considerations: NFPA 15 allows up to 7.94 m/sec of water velocity for the deluge downstream side. However, please check project piping design philosophy where velocity may be limited to 5 m/sec downstream of the deluge valve and 3 m/sec upstream.
  • Design of the system should be such that the water spray fully covers the equipment in within 30secs upon activation.

 

Leave a Reply

Your email address will not be published. Required fields are marked *

*