FOGEX HIGH-PRESSURE WATER MIST CYLINDER SYSTEMS

Transcription

1 Manual FOGEX HIGH-PRESSURE WATER MIST CYLINDER SYSTEMS User Guide Issue 1 October 2004 Assessed to ISO 9001: 2000 Certificate number 018

2 Chapter 2 Safety and Environmental Considerations Safety is of paramount importance. No-one should interfere or operate water mist systems without the proper training and instruction. All personnel who are assigned to maintain and operate the equipment should be properly trained. Water Mist (Fire) Technologies Ltd recommends that all personnel involved in such activities are accredited by Water Mist (Fire) Technologies Ltd and are in possession of the relevant IOSH Safety Passport or CSCS Skills Card. All personnel working in an enclosure protected by a water mist system should be warned of any and all dangers associated with such. Personnel in the protected area should be trained in the modes of actuation in case of fire and system activation. All personnel operating on the system should wear the appropriate PPE (Personal Protective Equipment), which should include as a minimum safety boots and goggles. As a safety measure, the protection cap supplied with the cylinders must always be fitted when the cylinder is being transported. During maintenance or building works that could activate the water mist system, e.g. dust in a detector, the system should be isolated or disconnected. Human safety relating to the deployment of water mist in manned areas has been addressed by the US Environmental Protection Agency (E.P.A). The overall conclusion was that water mist using potable water is safe for use in occupied areas. Areas protected by a water mist system should be evacuated in the event of a fire alarm, not because of the application of mist itself but in order to prevent harm to personnel due to exposure to the fire and its combustion products. Water mist can significantly reduce visibility in the protected areas during discharge. It will dissipate fairly rapidly afterwards, depending on factors such as air temperature and humidity. The design of escape routes should take into account this fact. Water mist using potable water does not present an environmental hazard unless the water absorbs dangerous substances from the fuel or fire. In such cases careful consideration should be given to preventing water entering the drainage system or the ground. Page 4 Watermist Fire Technologies

3 Chapter 3 Design of the System The design of the system will determine the system performance and user expectations. It is important to review the design with the system supplier. At present, there are no European prescriptive water mist standards. However, the product supplied will be in accordance with the relevant product and technical standards available at the time of design. These documents are referenced in Appendix 2. Specific details such as system run time, nozzle type and from this, water quantity, will have been determined by specific type testing for the application; fuel type; size and layout of the protected area and contents therein; insurer requirement; fire brigade attendance time; consultant brief; particular manufacturer recommendations; or a combination of the above. Water mist systems are designed to perform one of the following functions: To extinguish a fire completely so that no re-ignition will occur To suppress a fire, so that extinguishment has taken place and intervention can occur to prevent further re-ignition To control a fire scenario, to allow time for evacuation or fire brigade attendance Particular system components, water quantity and run time should be detailed in the Commissioning Certificate and Appendix 1. Water Mist Fire Technologies Page 5

4 Chapter 4 System Components FOGEX high-pressure water mist cylinder systems are based on similar technology. The actual components used will depend on the particular design of the application. The FOGEX water mist system comprises of the following main components: One or more 67.5 litre nitrogen cylinders charged with nitrogen to 230 bars at 15 o C Nitrogen valve, dependent on the type of system and number of cylinders can be one of the following:» Indirect High-Pressure Valve (for automatic closed head systems)» Electric valve for open deluge systems» Pneumatic valve (where there is more than one nitrogen cylinder)» Manual release valve (mounted on master nitrogen cylinder valve) Pressure regulator Pressure monitoring gauge (mounted on all nitrogen cylinder valve(s)) Discharge monitoring pressure switch Low pressure monitoring switch 67.5 litre water cylinder (plastic lined) Water valve (actuator head), fitted into each water cylinder Interconnecting hoses Water manifold (where more than 1 water cylinder is installed) Check valve (where more than 1 water cylinder is installed) Test point Directional valve Stainless steel pipe work Stainless steel compression fittings FOGEX water mist nozzle(s) The quantity of the water and nitrogen cylinders depends on design factors including the number and type of nozzle and the system discharge (or run) time. The ratio of water to nitrogen cylinders is 2:1. Cylinder configurations are normally as indicated in Table 4.1. Page 6 Watermist Fire Technologies

5 System Designation Qty of water cylinders Qty of nitrogen cylinders Total System Water Qty litres litres litres litres litres litres Table 4.1 Quantity of Water and Nitrogen Cylinders Nitrogen Cylinder The nitrogen cylinder has a water capacity of 67.5 litres and is charged with 230 bars of dry nitrogen at 15 o C. The cylinder is seamless with a working pressure of 230 bars and a test pressure of 345 bars. The cylinder is π-marked and complies fully with the European Transportable Pressure Directive. A system may have more than one nitrogen cylinder. In this case, it is always the first (or master) cylinder that is fitted with the discharge-initiating valve. Figure 4.1 Nitrogen Cylinder fi tted with protective head cap Indirect High-Pressure Valve The Indirect High-Pressure Valve (IHP) is fitted to the first nitrogen cylinder of closed-head systems that contain FOGEX FA automatic bulb-type nozzles. Figure 4.2 Indirect High-Pressure Valve as used on the fi rst (master) nitrogen cylinder The valve comes complete with the following attachments and outlets: Pressure Gauge Discharge Outlet Low pressure actuator c/w manual ball valve Manual release c/w gauge for low-pressure side and manual ball valve Water Mist Fire Technologies Page 7

6 The IHP valve is a differential pressure valve that is normally closed. The valve is held closed by a balance from the high pressure side of the stored nitrogen with that of the low pressure side at the top of the valve. The low pressure outlet is fitted with a ball valve and then is connected via a non-return valve to the system pipe work. The high pressure discharge outlet also connects to the system pipe work via a T piece. Upon commissioning, the system pipe work is pressurised to 19 bars, and the manual ball valve to the low pressure actuator is opened. When one or more nozzles actuate the pressure drops in the pipe work. The drop in pressure causes a pressure difference across the valve. The valve opens releasing the cylinder contents at 230 bars through the discharge outlet. The nitrogen flows via a pressure regulator, where the pressure is reduced to 110 bars. It then flows to pressurise the water cylinder(s). Other nitrogen cylinders that maybe connected to the system are actuated via the pressure opening a pneumatic valve. Electric Nitrogen Valve The electric nitrogen valve is used on open deluge systems only, that use the FOGEX F type nozzle. A signal from the fire alarm control panel opens the valve to discharge the nitrogen. The valve comes complete with the following attachments and outlets: Pressure Gauge Discharge Outlet Low pressure switch Manual release Figure 4.3 Electric Valve as used on the fi rst (master) nitrogen cylinder of open deluge systems Pneumatic Nitrogen Valve A pneumatic valve is used where more than one nitrogen cylinder is required. The valve is opened by external pressure generated through the opening of an IHP valve, electric valve or manual release of the first nitrogen cylinder. Page 8 Watermist Fire Technologies

7 Figure 4.4 Pneumatic Valve as used on all secondary nitrogen cylinders Manual Release The manual release requires the user operate to open the first nitrogen cylinder to initiate a system discharge. Figure 4.5 Manual Release as fi tted on the IHP valve on the fi rst nitrogen cylinder Figure 4.6 Manual Release as fi tted on the electric valve on the fi rst nitrogen cylinder The manual release should only be used in the following cases: On manual only systems; When a fire has been identified and intervention is required before the detection system has operated; If the detection system has failed Water Mist Fire Technologies Page 9

8 Pressure Regulator The pressure regulator is a device that reduces the pressure discharged from the nitrogen cylinder from 230 bars to 110 bars. This ensures that the optimum design pressure of 100 bar at the nozzle is achieved allowing for potential pressure loss in the pipe work and fittings. Figure 4.7 Pressure Regulator Low Pressure Switch The low pressure switch is fitted to all nitrogen cylinders to monitor loss of pressure. The switch is a volt-free contact set at 160 bars that should be connected and monitored by the control panel. Should the nitrogen pressure fall below this a fault is generated. The nitrogen should be recharged as soon as possible thereafter. Discharge Pressure Switch The discharge pressure switch is a monitored volt-free contact that is normally open. In the case of a single water cylinder arrangement it can be fitted to the water cylinder valve, nitrogen valve, or via a T -piece in the downstream pipe work. For more than one water cylinder the pressure switch is fitted to the manifold. As the water discharges the switch closes and a signal is sent to the control panel, indicating system discharge. An alternative arrangement is on the nitrogen cylinder valve. In this case, switch closure is achieved through the flow of nitrogen at pressure when the valve opens. The discharge pressure switch is stainless steel in construction. Figure 4.8 Discharge Pressure Switch Water Cylinder The water cylinder has a water capacity of 67.5 litres. The cylinder is seamless with a working pressure of 200 bars and a test pressure of 300 bars. The cylinder is π-marked and complies fully with the European Transportable Pressure Directive. The cylinder is lined with a plastic coating to prevent corrosion of the steel. The water used is de-mineralised. Page 10 Watermist Fire Technologies

9 Figure 4.9 Water Cylinder c/w Valve Water Cylinder Valve The water cylinder valve consists of two nitrogen ports (one in, one out); and an outlet port. The outlet section of the valve is a service removable. The ½" outlet is connected directly to the pipe work for a single cylinder system or to a manifold for a multi-cylinder system. The quiescent storage pressure of the water cylinder is zero. To ensure that the system operating pressure of 100 bars is attained quickly the internal valve mechanism has been tested to operate at no more than 80 bars. At this point, the valve opens and water discharges through the system to the nozzles. Should one of the nitrogen ports not be used, a blanking plug is inserted. Water Manifold A water manifold is a device that collects all the water outlets from the water cylinders. Water manifolds may be one of two sizes: 3-port, allows connection of between 1 and up to 3 water cylinders 6-port, allows connection of between 1 and up to 6 water cylinders Figure 4.10 Manifold Assemblies The inlet and outlet ports of the manifold are as follows: 3-port water inlet manifold» 3 off ½" inlet ports from water cylinders» 4 off ¾" outlet ports 6-port water inlet manifold» 6 off ½" inlet ports from water cylinders» 5 off ¾" outlet ports Water Mist Fire Technologies Page 11

10 At least one outlet port connects to pipe work that extends to the nozzles. Orientation of the outlet ports mean that one or more choice of direction is available for the pipe work extending to the nozzles. The other outlet ports may be used as connections to: A test point used for system pressure test or charging A discharge pressure switch Check Valve A check valve is a non-return valve that prevents the flow of water or nitrogen back through the manifold to the storage cylinder. It also prevents system failure or potential injury should one of the connected cylinders be removed from the system. Figure 4.11 Check Valve Directional Valve A directional valve is a manual or more normally an electric ball valve, installed in line with the pipe work. Its purpose is to direct the flow of water upon discharge to a particular area of the system. An example would be a common cylinder bank protecting 3 risks. The water quantity could be designed so that only sufficient water was available for a single risk. Upon detection of a fire, the system would be activated and only the directional valve associated with the risk with a fire would be opened. Figure 4.12 Manual Ball Valve that can operate as a directional valve Figure 4.13 Electric Ball Valve that can operate as a directional valve Page 12 Watermist Fire Technologies

11 Directional valves are only generally used when a risk assessment or insurer has determined that no more than one fire incident will occur. Water quantity will always be for the largest risk. In the above case, if one risk were larger than the remaining two, the water quantity would be determined on the largest risk. Compression Fittings A compression fitting consists of a body constructed out of 316L grade stainless steel, a locking nut and a compression ferrule. Compression fittings can have either one ferrule or two ferrules. Tightening of the locking nut compresses the ferrule(s) onto the pipe and forms a leak-tight seal. Different fitting types include stud couplings (a combination of a compression coupling to a BSP thread); bushes (male-female adaptors); sockets; male-male adaptors; bonded seals; adaptors with parallel and/or tapered BSP threads; tees, elbows, crosses, caps and plugs. Figure 4.14 Examples of Stainless Steel Compression Fittings Nozzles The type of nozzle used will depend on the type of system (see below). There are two basic types of nozzle: Open Deluge (or F nozzle) Closed-Head (or FA nozzle) Both types of nozzles are constructed of an aluminium-bronze or stainless steel body dependent on the application. All nozzles are fitted with a stainless-steel strainer within to prevent blockage. Figure 4.15 Open deluge F type nozzles The closed-head nozzle contains an alcohol filled bulb that is temperature dependent. Once the temperature has been achieved the alcohol will expand, and the bulb will shatter, opening up the nozzle. Water Mist Fire Technologies Page 13

12 Figure 4.16 Closed-head FA type nozzles For particularly harsh or dirty environments, or applications where the nozzle could be tampered with, tamper-proof blow-off caps are available. Figure 4.17 Tamperproof blow-off cap for an open deluge F type nozzle Figure 4.18 Tamperproof blow-off cap for a closed-head FA type nozzle Page 14 Watermist Fire Technologies

13 Chapter 5 System Operation This chapter details how the system will operate in an event of a fire. There are two types of system: one type uses the FOGEX F-type - open deluge nozzle (i.e. F20, F27 or F11); the other type uses the FOGEX FA-type automatic bulb nozzle (i.e. FA20, FA27 or FA11). These types of systems are referred to as open deluge and closed head respectively. Open Deluge Open deluge systems use the F range of FOGEX nozzles. Once the system is activated water mist is generated at each and every nozzle Table 5.1 below details the application of the types of nozzle: Type of Nozzle Flow Rate per Nozzle Application F litres/min General room protection below 5m in height F litre/min Door opening or water curtain protection below 5m in height; escalator protection; oven or fat-fryer protection F11 10 litres/min Local application or general room protection above 5m height Table 5.1 Types and applications of the F series open deluge nozzles Open deluge systems are most commonly activated by a detection system. The detection system type will depend on the application. Heat probes are generally used in ovens; flame detectors on printing presses and optical or ionisation smoke for general room applications. Activation of the system will be by the co-incidence connection principle, whereby at least two detectors, wired on separate circuits, will register an alarm or fire condition. The control panel will then signal to the water mist to discharge, after a pre-programmed delay time. Open deluge systems can also be activated manually, either by way of a manual release fitted to the first nitrogen cylinder (without the requirement for a detection system); or via the manual release or break glass of the detection circuit. Open deluge systems will use an electric valve fitted with manual release override on the first nitrogen cylinder. The nitrogen flows out of the discharge port, through the pressure regulator and into water cylinder(s). The water cylinder(s) discharge water at 110 bars into the system pipe work and to the nozzles. The nitrogen will also open the remaining nitrogen cylinders installed via their pneumatic valve. NOTE In an open deluge system water mist will discharge from all open nozzles. As the water flows through the pipe work a pressure switch will close, indicating that discharge is taking place. Water discharge will continue until all of the water has been depleted, unless an isolation valve (if fitted) is closed. Water Mist Fire Technologies Page 15

14 Closed Head Closed head systems use the FA range of FOGEX nozzles. Each nozzle is fitted with an alcohol-filled, temperature-sensitive bulb. The system will only discharge water if one or more of the bulbs are activated. The system is designed for the worst-case scenario where a designed maximum number of nozzles could be actuated. The water quantity required, and hence the number of cylinders, requires this maximum area of coverage, design runtime and nozzle flow-rate at design stage. The type of nozzle and the temperature of the bulb installed will have been determined at design stage. Table 5.2 below details the application of the types of nozzle: Type of Nozzle Flow Rate per Nozzle Application FA litres/min General room protection below 5m in height FA litre/min Door opening or water curtain protection below 5m in height FA11 10 litres/min Local application or general room protection above 5m height Table 5.2 Types and applications of the FA series closed-head nozzles Table 5.3 indicates the temperature release ratings of the alcohol filled bulbs. Bulb Temperature Rating Bulb Colour 57 o C Orange 68 o C Red 79 o C Yellow 93 o C Green 141 o C Blue 182 o C Mauve 240 o C Black Table 5.3 Colour designation of alcohol fi lled temperature-sensitive bulbs The 57 o C bulbs are fitted as standard. A closed-head system has to be charged with either dry nitrogen or water during the commissioningphase. This pressure is the normal quiescent pressure of operation. At 15 o C the pressure contained in the system pipe work and held back at the nozzle is 19 bars. A closed-head system always uses one nitrogen cylinder with an Indirect High Pressure (IHP) valve. If more than one nitrogen cylinder is installed the remaining nitrogen cylinders are fitted with a pneumatic valve. In the event of a fire that activates a bulb, the pressure will drop in the system, which will open the IHP valve on the first nitrogen cylinder. The nitrogen flows out of the discharge port, through the pressure regulator and into water cylinder(s). The water cylinder(s) discharge water at 110 bars into the system pipe work and to the nozzle that activated. The nitrogen will also open the remaining nitrogen cylinders installed via their pneumatic valve. Page 16 Watermist Fire Technologies

15 NOTE In a closed head system water mist will only discharge from nozzles that have activated. All other nozzles will remain closed unless activated through temperature of the fire spread. As the water flows through the pipe work a pressure switch will close, indicating that discharge is taking place. Water discharge will continue until all of the water has been depleted, unless an isolation valve (if fitted) is closed. Water Mist Fire Technologies Page 17

16 Chapter 6 Post-Discharge & Recharge Procedure In the event of a system discharge, precautions should be made and a procedure adopted for recharging and re-commissioning the system. In the event of a fire the protected area should not be re-entered unless deemed safe to do so by the local fire brigade or other suitably qualified personnel. Should there be any standing water near electrical equipment where possible live-voltages may be present, power should be shut-down, and suitable health and safety precautions should be followed. The authorised supplier or maintainer of the system should be contacted as soon as possible to recharge and re-commission the system. Nitrogen and water cylinders will need to be recharged. The water cylinder valve will need to be refurbished in accordance with the manufacturer s procedures. The nozzle(s) through which water has discharged should be removed and replaced. This is to ensure that system performance remains unaffected for subsequent activations. In the case of automatic closed-head bulbs, the alcohol filled bulb will need to be replaced, if activated or damaged. Should any tamperproof nozzle caps have been damaged or discharge has occurred, these should be replaced. Page 18 Watermist Fire Technologies

17 Chapter 7 Maintenance Procedures For the water mist system to protect and operate at optimum performance for the life-time of the application certain maintenance procedures should be followed. The system has been designed to meet the design criteria and application at the time of installation. Change of use, fire hazard, size or construction may affect the performance of the system and the system supplier should be contacted as soon as possible after any such changes. Inspection intervals and procedures are as indicated below. Weekly Visual check of the hazard for changes or alterations that could affect the system performance. Visual check of the control panel to check for faults. Inspect pressure gauges on the nitrogen cylinders for correct reading. If installed, check trace heating and localized heating systems. Carry out a visual check that there is no obvious damage to pipe work. Carry out a check that all operating controls and components are properly set and undamaged. Monthly Check that all personnel who may have to operate the equipment or system are properly trained and authorised to do so and, in particular, that new employees have been instructed in its use. Six Monthly To be carried out by qualified and authorised service providers. Check connecting hoses for tightness and integrity Check water cylinder contents Inspect support brackets and frame of cylinders/manifold Inspect and test the fire alarm system, if fitted. Yearly Check water quality for signs of deterioration or bacterial contamination. Ten yearly Ensure all cylinders undergo a hydrostatic test in accordance with current standards. Water Mist Fire Technologies Page 19

18 Appendix 1 Particular System Specification Client Name Client Address Telephone Fax Responsible Person Protected Hazard Fuel Class (please circle) Class A Class B Particular Fuel Type of System (please circle) Open Deluge Closed Head Type of Actuation (please circle) IHP Electric Manual Self-contained Type of Detectors Type of Control Panel Type of Nozzle Number of Nozzles (include any in voids) Tamperproof blow-off caps (please circle) Yes No System Design Run Time Total Water Quantity Number of Water Cylinders minutes litres Number of Nitrogen Cylinders Number of Directional Valves Type of Directional Valve Date of Installation Date of Commissioning and Handover As Fitted Drawings present (please circle) Yes No Hydraulic Calculations present (please circle) Yes No Page 20 Watermist Fire Technologies

19 Other Information Authorised Signature Name Position Date Water Mist Fire Technologies Page 21

20 Appendix 2 Relevant Documentation FOGEX Design and Installation Manual NFPA750 Standard on Water Mist Fire Protection Systems (2003) Draft ISO Standard ISO Fire protection Automatic sprinkler system Part 9: Requirements and test methods for water mist nozzles CEN/TC 91 Draft on Fixed fire fighting systems Water mist systems Design and installation TBN 14 Loss Prevention Council Technical Briefing Note Legionella and Fire Fighting Systems, May 1999 BS (2002) Part 1: Code of Practice for System Design, Installation, Commissioning and Maintenance BS6266 (2002) Code of practice for fire protection for electronic equipment installations BS EN 1968 (2002) Transportable Gas Cylinders Periodic inspection and testing of seamless steel gas cylinders Page 22 Watermist Fire Technologies