常见干式及预作用系统设计问题及故障

1、Automatic Sprinkler SystemImportance of Sprinklers First line of protection small fires Enhanced protection Business protection less interruption of business operations Less loss Firefighter safety Types of Sprinkler Systems Wet pipe Dry pipe Pre-action Deluge Water Supply for Sprinklers Municipal W

2、ater tower Reservoir Pressure tank Fire department Types of Control ValvesIndicating valves open or closed Post Indicator Valve P.I.V. Outside Stern Screw and Yolk - O.S.& Y Butterfly valve Gate valve Ball valve Wet System Fire department connection - siamese Control Valves and Trim Alarm valve

3、Check valve Wet SystemInspectors test valve Water motor gongs Gauges street and system Piping Automatic sprinkler heads (closed) - Upright, pendent and sidewall Operation Dry Pipe SystemFire Department connection siamese Control valves and Trim Indicating valves - wall indicator, post indicator, OS&

4、amp;Y Dry pipe valve Check valve Inspectors valvesDry systemWater motor Gauges air and water Piping Automatic sprinkler heads (closed) upright, sidewalls and dry drop pendent Compressors Enclosures heated Gongs Differential Differential dry-pipe alarm valves: 1. High Differential Valves (most common

5、) The differential pressures in most of these valves are either a 5:1 or 6:1 ratio. In determining the amount of air pressure required to keep the valve closed would be 1/6 or 1/5 that of the incoming water pressure from the street main or other source of water. 6:1 Calculation: Street water pressur

6、e = 600 kPa Air pressure required = 600 divided by 6 = 100 kPa (will hold the clapper valve closed.) It is customary to add some extra air pressure to prevent the valve from tripping during pressure surges. The usual amount is 140 kPa. Therefore, for our calculations above the final answer would be:

7、 100 + 140 kPa. = 240 kPa. Differential 2. Low Differential Valves 1.1:1 These valves use a much lower differential air pressure. A 1.1 to1 differential is most common. In other words the air pressure required to hold the clapper closed will be 110% of the incoming water pressure. See textbook for t

8、he advantages of these types of valves. General: Note that on a dry-pipe system much of the trim is located below the clapper valve. The reason for this is to prevent air leaks. As well, note that the clapper once opened is held open by a catch. This facilitates draining the system after use. Unlike

9、 the wet pipe system, the main drain on a dry pipe system is below the alarm valve. Deluge System Fire Department Connection siamese Control valves and Trim Indicating and pre-action Gauges air and water Piping Deluge System Automatic Sprinkler Heads (open) upright and sidewalls Automatic Detection

10、Devices electric and pneumatic Operation Pre-action System Fire department Connection Siamese Control valves and trim indicating and dry pipes Gauges air and water Piping Pre-Action System Automatic sprinkler heads (closed) upright and sidewalls Automatic Detection Devices electronic, pneumatic, det

11、ection Control panel Operation Common Problems Fire Department connection not capped, threads damaged, obstructions in piping, visually obstructed Control valves and Trim closed/obstructed, not supervised or locked open, not listed, not indicating, insufficient air pressure, dry pipe flooded, and va

12、lve water column Common Problems Gauges broken or missing, not listed, improper pressure Piping not secured, supporting items not associated with sprinklers Automatic sprinkler heads damaged, painted, improperly installed, physically obstructed, improper temperature rating Compressors power off Enclosures lack of heat Common Prob