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Hvws

Description
High velocity water spray
Transcript
  HIGH VELOCITY WATER SPRAY SYSTEM (HVWS) I NTRODUCTION HIGH VELOCITY SYSTEM IS USED TO EXTINGUISH FIRE INVOLVING HYDROCARBON LIQUIDE WITH FLASH POINT WITH OR ABOVE 65 DEGREE CENTIGRADE .HVWS USE HIGH VELOCITY SPRAY NOZZLE NOZZLE USED FOR SYSTEM IS KNOWN AS ‘’PROJECTOR’’   SYSTEM USES ACTUATION SYSTEM TO RELEASE WATER KNOWN AS ‘’DELUGE VALVE’’  High velocity water spray system WORKS ON PRINCIPAL TO EXTINGUISHMENT FIRE IS COOLING, SMOTHERING AND EMULSIFICATION. DELUGE VALVE: DELUGE VALVE (DV) IS ALSO KNOWN AS A SYSTEM CONTROL VALVE IN A DELUGE SYSTEM, USED FOR FAST APPLICATION OF WATER IN A SPRAY SYSTEM. DELUGE VALVE PROTECTS AREAS SUCH AS POWER TRANSFORMER INSTALLATION, STORAGE TANK, CONVEYOR PROTECTION PROTECTION AND OTHER INDUSTRIAL APPLIANCES ETC. DV CAN ALSO BE USED TO PROTECT AIRCRAFT HANGER AND FLAMMABLE LIQUID FIRES. DV ASSEMBLY MAINLY CONSISTS OF FOLLOWING PARTS: a) In line strainer, b) Isolation valve, c) Deluge valve, d) Actuator/pilot assembly, e) Drain valve, f) Pressure gauges (above and below the deluge Valve), and g) Alarm assembly (consisting of gong or Sounder).  INSTALLATION a)   Deluge valve shall be installed outside but adjacent to the protected area as close to the risk as possible but at not less than 6 m from the plant and/or equipment to be protected. b)   Masonry wall shall be provided to protect the deluge valve from external impact.   c)   Isolation valve shall be provided to ensure mantainence and cleaning purpose. d)   Isolation valve shall be provided above the deluge valve for testing purpose.   e)   Isolation valve shall be strapped and locked open position.  f)   Emergency manual override facility shall be provided for actuation the deluge valve. g)   It is permissible to provide manually operated bypass line with isolation valve for an emergency requirement. h)   Load on deluge valve shall not exceed the limit mentioned below; Valve size litre per minute 150 mm 13500 100 mm 5000 80 mm 1150 I) Indication shall be provided for open and closed position. J) Facility shall be provided to prime the space above the deluge to seat with water. K) There must be facility to prevent backing of water into the instrument air supply in the event of diaphragm failure. DELUGE VALVE AT BORL Deluge valve at BORL installed by HD FIRE PVT. LTD. MODEL- A (CAST IRON) MODEL SPECIFICATION MODEL A NOMINAL SIZE 200,150,100,80 & 50NB MAXIMUM PRESSURE SERVICE 12 BAR THREADED OPENING BSPT HYDROSTATIC TEST PRESSURE 25Kg/sq.(350psi) MOUNTING 90 DEGREE PATTERN INLET TO OUTLET VERTICAL MOUNTING  NET WEIGHT WITHOUT TRIM 200NB - 214 KG 150NB - 131 KG 100NB - 77 KG 80NB - 50 KG 50NB - 47 KG VALVE OPERATION The deluge valve has an inlet, outlet and priming chamber. The inlet and outlet are separated from the priming chamber by the valve chamber and diaphragm in the ‘SET’ position, pressure is applied to the priming chamber through a restricted prime line. The pressure on the seat due to the differential design. In the set position, the clapper separates the inlet from the outlet keeping the system piping dry. When the pressure is released from priming chamber faster than it is supplied. Through the restricted priming line, the clapper moves and allows the inlet water supply to flow through the outlet into the system and associated alarm device. The outlet into the system and associated alarm device. The mode of actuation of deluge valve can be pneumatic or hydraulic type or a combination of both. TRIM DESCRIPTION Basic trim is required on deluge valve regardless of the release system. it contain those component which are required in all types of installation such as main drain valve , priming connection , emergency release valve ,pressure gauge. There are three types of trim available for this model which is as follow A)   Dry pilot tube (pneumatic release) B)   Wet pilot tube (hydraulic release) C)   Electric release trim DRY PILOT TRIM Dry pilot operation uses a pilot line of closed sprinkler containing air under air pressure ,located in the area to be protected it require regulated dry air supply with main supply point through restricted orifice.   The pilot line is connected directly to the top of positive drain actuator (PDA). The bottom of PDA Is connected to the top chamber of the deluge valve. When the air pressure drops, due to release of any the release device on detection of fire, the diaphragms of PDA is lifted and allow the water to drain. This reduces the water pressure in the top chamber of deluge valve and when the pressure in the top chamber reaches 50% of supply pressure, the deluge valve opens. The direct drain of PDA starts when the top chamber pressure of deluge valve reaches approximately 0.7 Kg/ sq .cm. The positive drain will not permit the deluge valve to close unless the PDA is set manually the recommended air supply pressure is as per TABLE LINE WATER PRESSURE Kg/sq. cm MAXIMUM AIR PRESSURE IN DETECTION LINE KG/SQ. CM MINIMUM MAXIMUM 2 1.2 3.0 4 1.5 3.0 6 2.0 3.5 8 2.5 3.5 10 3.0 3.5 12 3.5 4.0 DRY PILOT TUBE Wet pilot operation uses a pilot line of closed sprinkler containing pressurised water, supplied through the upstream side of the deluge valve through a restricted orifice all release are connected to to a common release of any one of the release devices, the water pressure in the top chamber of deluge valve reaches 50% of the supply pressure, the deluge valve. ELECTRIC RELEASE TRIM
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