Water Spray System Design Methodology

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We have compiled some very basic points for effective designing of a water spray system. For more detailed information, refer to NFPA 15, which is the Standard for Water Spray Fixed Systems for Fire Protection. Water Spray Systems are basically used for fire control, extinguishing, cooling, prevention and/or exposure protection of industrial hazardous locations.

As per NFPA 15, for a typical water spray system, the design density of spray ranges from 4.1lpm/sq.m to 20.4 lpm/sq.m – depending on the application and hazard type. The minimum operating pressure of any nozzle protecting an outdoor hazard is stipulated at 20 psi (1.4 bar).

Major steps in designing effective water spray system

Establish design area (area to be sprayed)
Determine dimensions
Determine water density (application rate)
Calculate water demand
Establish nozzles required (K-factor & Spray Angle)
Determine Nozzle Orientation
Determine number and type of nozzles required to give adequate water coverage
Adjust K-factor & Spray angle - Recalculate
Finalize the design

Design Objective	Hazard Type	LPM / Sq. Meter
Exposure Protection	Vessel surface	10.2
	Horizontal structural steel	4.1
	Vertical structural steel	10.2
	Cable trays / runs	12.2
	Transformers	10.2
Extinguishment	General	20.4
Extinguishment	Conveyor belts	10.2
Control of Burning	Pumps and compressors	20.4
Control of Burning	Liquid pool fires	12.2

Special Projects

In addition to the design and manufacture of standard fire-fighting products, we can also provide customised and bespoke engineered systems to meet individual customer needs or applications for special projects. Special units and skids are made on demand according to your specifications. Our technical service and engineering teams can assist you on special project requirements for various fire-protection and related applications. From initial concept and design to commissioning and on-site assistance, we can offer our support
One such example was use of Varsha Nozzles for sound suppression application in ISRO rocket launch station. Our Varsha nozzles were used for excessive sound suppression during the GSLV Mark III launch. Acoustic sound suppression was developed by ISRO in order to suppress large decibel sound by attenuating noise using water quenching method. Selection of HD Varsha Nozzles was made to ensure that water jet from all ends meet at the definite points of launch pad. Extensive performance tests of Varsha nozzles were carried out in Jalgaon.

Data Centers

Uptime of Data centers remains critical to most of the businesses today due to cloud-based models. Data centers and server rooms can consist of very costly as well as fragile devices – responsible for backing-up several critical industries. Any problem or down time can be extremely problematic to business continuity of many industries. Therefore automatic and fast-acting fire fighting systems are ideal for such applications.
Data centers and server rooms are typically protected by “total-flooding” clean agent inert gas systems. Inert gas fire suppression agent is made up of 100% argon, nitrogen, or mixture of both and/or CO2. Most popular being the IG-541 system, consisting of 52% Nitrogen, 40% Argon and 8% Carbon Dioxide. These inert gasses are non-reactive to chemical interactions, making them exceptionally safe and effective for putting out fires in data centers. IG-541 extinguishes the fire by reducing the residual oxygen concentration to a level that no longer supports combustion.
Alternately, even a Single or Double-Interlock Pre-Action system can be effectively used in protection of data centers and server rooms, in cases where sprinkler system needs be used with multiple detection mechanisms.
Protection of stand-alone electrical cabinets and machines can be done with CO2 based automatic fire suppression systems like HD-RAKSHAK, a system within the electrical cabinet itself, close to circuits where a fire can occur. The fire detection tubing actuates the system and instantly floods the entire cabinet area with CO2 extinguishing agent.

Commercial & Residential Buildings, Hotels and Airports

The automatic wet pipe fire sprinkler system is most common type of sprinkler system installed in buildings. Alarm valves act as check valves and to give an alarm in case of fire. The alarm is through water motor gong audible alarm bell or through a signal from pressure or flow switch.
This applies to commercial buildings, hotels, meeting rooms, logistics areas and production buildings or warehouses. In case of fire, the sprinkler system is automatically activated during the initial phase, thus preventing the fire from spreading. Sprinkler systems are designed in accordance to NFPA 13.
The pre-action system is used when it is required to have two triggers in order to start water flow through the sprinkler system. It greatly helps that the pre-action fire sprinkler can be set to prevent water from spouting in case of a false alarm or a mechanical failure. The pre-action system is good for use in places where the sprinklers are necessary in case of actual fire only so there is no water damage of any items in building due to inadvertent opening of sprinklers.

Power Plants

Power plants are characterized by their complex systems consisting of many high-risk areas and therefore reliable fire extinguishing systems are essential to ensure the safety in such places.
Steam and gas turbo generators operating at high temperature and speed contain large quantities of lubricating oil and constitute to a major risk of fire. Deluge water spray systems are commonly used in the protection of such machines.
Coal is transported on encased conveyor belts that run across coal processing stations. Fire detection and medium velocity automatic deluge water spray systems are most suitable for protection of coal conveyor belts.
Pre-action water spray systems are best suited for turbine fire protection because of their high assurance against inadvertent discharge
In certain risk areas, fire-fighting foams are added to deluge systems to reinforce the fire-suppression effect.
High-velocity water spray nozzles for protection of fixed hazards such as transformers, circuit breakers, turbo alternators, lube oil systems, oil fired boilers, and similar hazards.
Outdoor oil-filled transformers containing over 500 gallons of oil should be protected by automatic deluge water spray systems.
Fixed water spray systems are designed as per NFPA 15.

Oil & Gas, Petrochemical

Deluge water spray fixed systems for cooling of storage tanks, bullets, spheres, structures, and flammable liquid storage areas. These systems are designed as per NFPA 15. HD deluge valves offer reliable and robust solutions. Deluge valves can be operated by manual, hydraulic, pneumatic or electric trims. HD medium velocity nozzles come in a combination of k-factors and spray angles to offer effective spray pattern for cooling applications.
Fixed foam systems for open top floating and cone roof flammable liquid storage tanks. These systems are designed as per NFPA 11. HD foam chambers and rim seal foam pourers cover a wide range of flow rates and offer effective foam discharge solutions, making these ideal systems for storage tank applications.
Foam bladder tank systems provide accurate, dependable, and cost-effective foam fire protection for a variety of flammable/combustible hazard areas, with no external power other than water pressure. Water is applied to the outside surface of the bladder, displacing foam the concentrate inside the bladder, which then is injected into the water stream.
Foam-water sprinkler systems for flammable liquid storage and handling areas. These systems are designed as per NFPA 16. Foam sprinkler systems are more effective than a water-only system when evaluated for the same risk. They provide for actual extinguishment of the fire and a lower water demand.
Custom engineered foam systems are ideal for foam proportioning applications for a range of foam discharge.
Range of monitors is used in petrochemical storage and refineries.