Water mist fire protection systems
AS 4587-2020 pdf download.Water mist fire protection systems – System design , installation , and commissioning.
6.5.6 Strainers
Strainers shall be made entirely of corrosion-resistant materials. For pressure-bearing parts and for the sieve, metallic materials shall be used. The flow direction shall be permanently marked on the body of strainers installed in pipelines.
In systems relying on an external reticulated water supply, a strainer shall be installed to separate the system from any incoming water supply and from any pipe, device or fitting upstream of the system which is not made of copper, copper alloy, stainless steel or galvanised steel.
A strainer shall also be installed between any galvanised pipework and the distribution pipework.
Strainers shall be selected to ensure that spheres with a diameter of more than 0.8 times the minimum nozzle waterway dimension cannot pass through to the nozzles. Each strainer shall have an aggregate open area of at least 1.5 times the cross-sectional area of the pipe in which it is installed.
The free flow through the distribution pipes shall not be obstructed, i.e. no part of the strainer shall protrude into that pipe waterway.
It shall be possible to take out the sieve and the dirt particles of strainers without having to remove the strainer housing.
If the nozzle strainer is projecting from the nozzle inlet into the pipe fitting, the design shall be such that a sphere with a diameter of 3 mm can pass between the inner surface of the pipe fitting and the outer surface of the strainer.
The pressure loss across strainers shall be taken into account in hydraulic calculations.
6.5.7 Pressure regulating valves (PRVs)
PRVs shall be installed when the supply pressure is higher than the design operating pressure of the water mist system. PRVs shall be capable of providing a stable regulated output at the rated flow capacity and design setting, over the full range of input pressures that will be experienced over the course of the discharge period.
Downstream pressure creep under no-flow conditions shall not exceed the lesser of the downstream components pressure rating or the pressure relief valve set point, if provided. Pressure set, pointadjusting mechanisms on the PRVs shall be tamper resistant, and the adjustment shall be indicated by a permanent marking. A means to indicate evidence of tampering shall be provided. The PRV’s set point shall be set by the manufacturer. Permanent markings shall indicate the inlet and outlet connections of the PRVs.
PRV set point shall be permanently etched or engraved on a tamper resistant label on the PRV and recorded on the block plan.
Cylinders shall be installed in an area maintained within the temperature range specified by the manufacturer, or external heating/cooling provided to keep the temperature of the storage container within the specified ranges.
When the storage container(s) is installed in the enclosure being protected, provision shall be made to ensure that the system operation is not adversely affected by its location.
Water storage tanks and cylinders shall be internally protected against corrosion.
Where storage containers of inert gas are located in areas where their leakage or operation of a pressure relief device could lead to development of a hypoxic atmosphere, a warning notice shall be provided to identify the potential risk together with adequate ventilation to minimize the hazard.
6.6.2.2 Pumpsets
Pumpsets supplying watermist systems together with their installation and accessories shall be of sufficient capacity to meet the system demand and conform to AS 2941 and any requirements of the system listing.
Pumpsets capable of pressurizing the system above its design pressure shall be provided with a suitably sized pressure relief valve. The system pressure shall not exceed the design pressure of any component able to be subjected to that pressure.
6.6.3 Storage containers
6.6.3.1 Pressurized containers
Containers used for water storage that are normally pressurized, or that are pressurized when the system is activated, shall conform with the requirements of AS 2030.1 or AS 1210 and be fitted with safety devices in accordance with AS 2613, as applicable.
6.6.3.2 Integral mounting brackets
Container mounting brackets or devices integral with the container, for attachment to structures, shall be designed to withstand the maximum expected mass, vibration and shock loading appropriate to the installation.
6.6.3.3 Pressurized storage container arrangement
The arrangement of pressurized storage containers and accessories for either water or gas, shall be as follows:AS 4587-2020 pdf download.
Water mist fire protection systems
