A Water Spray System, for Fire Protection a different variant of Fire Sprinkler System. Such a system is used in places where fire is likely to rapidly spread out of control, within a short duration. Examples of such places, where Water Spray System, for Fire Protection are required are; Transformers, Compressors, Condensate Storage Tanks, LPG bullets and Combustible fuels.
Is it compulsory to have/install, Water Spray System, for Fire Protection?
It depends on the type of system, equipment or inflammable liquid, in use. If however, you are using any substance that are highly inflammable, combustible or catch fire and spread quickly. This system is a mandate for you.
How Water Spray System, for Fire Protection, Works?
Let us take an example to be more specific and clear. In an oil cooled transformer, the oil is likely to catch fire after a certain temperate is exceeded and instantly the entire transformer will catch fire and burn from all sides; even though the transformer is made up of metal. To avoid this, kind fire, we use Water Spray System.
Here, there may be multiple metal rings of detectors, a detector is nothing but a temperature sensing element. This detector ring is placed next to the most likely sots where the temperature is about to exceed or fire is about to take place. Also the, entire transformer is surrounded by multiple sprays, at multiple levels. A spray is nothing, but a sprinkler without the temperature sensing, bulb.
When the fire does take place, the detector ring detects this; and gives the signal to the deluge valve or all the sprinkler surrounding the transformer to start all at once. Hence the entire transformer is flushed with water, to cool it down.
There are two variants of Water Spray System, for Fire Protection:
1) High Velocity Water Spray Systems (HVWS)
2) Medium Velocity Water Spray Systems (MVWS)
High Velocity Water Spray Systems (HVWS):
HVWS, is generally used in oil based systems, having high flash points. The velocity of the water sprays, hitting the system under fire is critical for successful fire extinguishing action.
Medium Velocity Water Spray Systems (MVWS):
MVWS, is generally used in oil based systems, having low flash points. The velocity of the water sprays, hitting the system under fire, if it is high, might actually spread the fire, and not extinguish it. Hence, the velocity of the water has to be in range.
Advantages of Water Spray Systems
- Extinguishes fires quickly and prevents fires from spreading over a large area.
- Minimises the damage caused by fire and reduces downtimes, protects the future of your business.
- High flexibility in design and implementation
- Reduces fumes and binds contaminants.
- Allows large open areas and thus a more flexible use of the premises.
- Uses water, a natural fire extinguishing agent that is available in unlimited quantities at a very low price.
Medium Velocity Water Spray System (MVWS):
Fires on Hydrocarbon are more frequent due to the volatility of the hydrocarbon and its property to not dissolve with water and lighter than water the fire extinguishing of hydrocarbon fire with water is not possible. In case of fire on Hydrocarbon if the water is sprayed, due to the light weight of the hydrocarbon it will float on the water and reignite them to fire and due to the speed of water the fire will travel from one place to other place. However for these plant water spray system can be provided as exposure protection. That means if any plant is under fire the plants nearby shall be kept cool with the water spray system, while plant under fire shall be applied foam.
Hence in this case where plant is using hydrocarbon the exposure should be protected with water spray system designed as per NFPA 15.
This system is mostly used for the protection of the following
- Expander & Sale Gas Compressors
- Off Gas Compressors etc…
Quartzoid Bulb Sprinklers (Q. B. S.) Detection is used to for detection of fire which will be connected to deluge valve for auto operation of the system. Q B Sprinklers shall be of 68 Deg or 79 Deg C or any other temperature depending upon the ambient temperature of the location of the plant.
For electronic automatic operation of the system the deluge valve shall be provided with pressure sensors, temperature sensors and annunciation panel.
Operation
In case of fire the Quartzoid Bulb sprinkler shall burst due to heat which allow water in the detection pipe to drain out and in process allow the Deluge valve to open fully. As soon as the Deluge valve opens the water shall flow through the piping to flow water to all water spray nozzles mounted on the ceiling of the plant. The water shall be sprayed in solid conical spray pattern to cover entire area of the plant floor so that the equipment installed shall be kept cool to avoid heat radiation and further ignition of fire.
The fire shall be control with the help of the water spray system.
The indication of operation of the system shall be available on the control panel with Alarming Siren.
Advantages of M.V. Water Spray System
- Entire area is flooded with foam, hence very useful for fire fighting in hazardous area, plant, storage tanks, etc. where manual approach is difficult.
- Very quick in response.
- The fire losses is kept low as the area under fire get foam blanket and also cooling due to water contain and so chances of spreading fire is negligible.
High Velocity Water Spray System (HVMS):
High Velocity water spray systems are installed to extinguish fires involving liquids with flash points of 65 C or higher. Three principles of extinguishment are employed in the system – emulsification, cooling and smothering. The result of applying these principles is to extinguish the fire within a few seconds.
This system is mostly used for the protection of the following
- Transformers, oil filled equipments of power stations
- Turbo-alternators and other
- Oil fired boiler rooms, oil quenching tanks.
Transformer protection shall contemplate on essentially complete impingement on all exterior surfaces except the underside, which may be protected by horizontal projection.
Transformer present particular design problems for Water spray protection, primarily due to their irregular shape and necessary clearances to be provided for the high voltage equipment. Generally speaking, there is much more interference with the water flow on the sides of the transformer than at their top. Due to this reason the protection usually involves a large number of small capacity projectors than a few bigger ones. Often it will be necessary to put more water on the transformer than required to achieve complete impingement and total envelopment.
All system components shall be so located as to maintain minimum clearances from live parts.
“Clearance” is the air distance between Water Spray Equipment including piping nozzles and detectors and un-insulated live electrical components at other than ground potential. The minimum clearance is 900 mm under normal conditions. During the operation of Water Spray system, they are intended for use as safe.
The sprayers shall be installed in rows around the transformer and above oil condenser .
Quartzoid Bulb Sprinklers (Q. B. S.) Detection is used to for detection of fire which will be connected to deluge valve for auto operation of the system. Q B Sprinklers shall be of 68 Deg or 79 Deg C or other temperatures depending upon the ambient temperature of the location of the plant.
Operation
Also See: Click Here for Deluge Valve Animation
A Deluge system (automatic High Velocity Water Spray System) is a fixed fire protection system, which totally floods an area with pressurized water through a system of piping with open nozzles & sprinklers. The system piping is empty until the controlling valve is activated by a hydraulic or other types of release systems. Deluge valve has an inlet, outlet & priming chamber. The inlet & outlet are separated from the priming chamber by the valve chamber & diaphragm. In the” SET “position, pressure is applied to the priming chamber through a restricted prime line .The pressure is trapped in the priming chamber & holds the clapper on the seat due to the differential area. When the pressure is released from priming chamber faster than it is supplied through the restricted priming chamber line, the clapper move & allow the inlet water supply to flow through the outlet into the system and associated alarm device.
Water spray System are installed to control fire & to provide cooling &/or exposure protection to such risks where extinguisher is always not possible or even desirable e.g. fire involving flammable fluids having flash points below 650 C (1500 F).
In case of fire the Quartzoid Bulb sprinkler shall burst at rated temperature due to heat which allow water in the detection pipe to drain out and in process allow the Deluge valve to open fully. As soon as the Deluge valve opens the water shall flow through the piping to flow water to all water spray nozzles mounted on the piping around the transformer. The water shall be sprayed in Hollow conical spray pattern to cover entire area of the transformer so that the fire on the transformer shall cool due to emulsification as well as fire get extinguish due to cutting off oxygen due to coverage pattern of the nozzle.
The fire shall be control and extinguished with the help of the H. V. water spray system.
The indication of operation of the system shall be available on the control panel with Alarming Siren.
Advantages of HM.V. Water Spray System
- Entire Transformer is flooded with water, which extinguish fire at earliest as well as avoid further destruction.
- Very quick in response.
- The fire losses is kept low as the area near fire get cooling due to water and so chances of spreading fire is negligible
WATER CURTAIN SYSTEM
WATER SPRAY NOZZLES
These are similar nozzles as of sprinkler but only difference is there is no bulb used and they are having open orifice which could not hold water pressure.
These nozzles are having threaded inlet and deflector at outlet and fitted on the pipe array as same as sprinkler. This system spray water from all nozzles as the control valve get open and there fore the area under fire receive water as well as the adjacent area also get water and reduces the chances of spreading the fire.
WATER SPRAY SYSTEM
The water spray system is basically most useful for various tanks storing hazardous liquids or chemicals.
The system consist of water reservoir, a pump of suitable capacity and pressure, delivery main, and distributing pipe array, main control valve(known as deluge valve), water spray nozzle and heat sensing element.
In case of fire the heat sensing element, mainly bulb type sprinklers burst when the rated temperature arrives and causes to open deluge valve due to pressure difference. The valve floods complete main and distributed pipes and start spraying from all the water spray nozzles at a time.
The spray remains under operation till the deluge valve is rest manually. This is most reliable and suitable system for tank protection as well as exposure protection.
Also Read: Fire Water Sprinklers Principle
Advantages of Water Spray System
- Entire area is flooded with water, hence very useful fore fire fighting in hazardous area, basement, storage tanks, etc.
- Very quick in response.
- The fire losses is kept low as the area adjacent to fire also get water protection and so chances of spreading fire is negligible
Disadvantages of Water Spray System
- As entire system get flooded with water the water damage is more.
- This system needs through maintenance and periodic checking of automatic operation for reliability during fire.
Thank you very much. This will be very helpful in my profession.
Hope to hear more about Fire pump selections.