The sprinkler system includes key inspection parts such as fire pump room, stairwell, elevator front room, basement, roof, etc., as well as end water testing devices; quality concerns such as pipeline brackets, hangers, and anti-sway bracket settings. So what are the common problems? And how can we prevent it?
Common problem 1
The installation position of the water flow indicator of the sprinkler pipe of the automatic sprinkler system does not meet the requirements, and the distance from the pipe bend and the valve does not meet the requirements
Causes and consequences: Failure to meet functional requirements or cause false positives.
Prevention measures and relevant regulations: The water flow indicator should be installed at a height of 1.8m above the ground. The water flow indicator should be installed at least 15cm from the elbow and at least 60cm from the valve. Special tools should be used for the opening of the pipeline, make sure that the opening is on the vertical line of the center of the pipeline, and clean the bore of the pipeline.
Common problem 2
The sprinkler system signal valve is installed behind the water flow indicator and connected directly to each other
Causes and consequences: The signal valve is not sensitive, and can not even display the flow of water in the pipe, and transmit it to the fire system command center.
Prevention measures and relevant regulations: The signal valve should be installed on the pipeline in front of the water flow indicator, and the distance between the two should not be less than 30cm.
Common problem 3
Use non-galvanized steel pipe for automatic sprinkler system or use galvanized steel pipe with diameter less than 25mm for connecting sprinkler branch pipes
Causes and consequences: The rust in the welded steel pipe or the seamless steel pipe will cause the sprinkler head to block, lose the function of automatic water spray and fire, and increase the fire loss.
Prevention measures and related regulations: The automatic sprinkler system must use galvanized steel pipes and the diameter of the branch pipes connecting the sprinkler heads shall not be less than 25mm.
The lower part of the wet alarm valve and the direction of the water flow indicator are not equipped with a signal valve but a common valve
Causes and consequences: close the valve when repairing the pipeline, and forget to open it due to carelessness after the repair. Once there is a fire, there is no water in the pipeline, there will be heavy losses.
Prevention measures and related regulations: Signal valves must be installed under the alarm valve and the direction of the water flow indicator. And check whether the signal when the signal valve is open or closed is returned to the fire control center. In order to prevent misoperation, a lock is also installed on the valve to prevent the valve from being accidentally closed.
Common problem 5
The roof fire water tank is connected to the outlet pipe (constant pressure pipe) of the wet automatic sprinkler system or the suction pipe of the fire pump of the automatic sprinkler system is not equipped with a filter device
Causes and consequences: The sundries in the water tank or pool enter the pipe network, causing blockage of the closed sprinkler head or failure of the alarm bell or pressure switch in the alarm valve, affecting the sprinkler fire extinguishing and alarm work.
Prevention and control measures and relevant regulations: the pipe outlet of the automatic sprinkler pressurize and supplement system. Decontamination filter facilities should be provided.
Common problem 6
Pipe diameter does not match the number of sprinklers
Causes and consequences: The construction was not carried out according to the design drawings, and the sprinkler heads were changed or installed more in the decoration stage, which could not achieve the effect of automatic fire extinguishing.
Prevention measures and related regulations: Carry out secondary design according to decoration drawings and requirements, and construct according to design specifications.
(1) The number of standard sprinklers controlled by each water distribution branch pipe on both sides of the water distribution pipe should not exceed 8 in light-hazard and medium-hazardous locations. There should not be more than 6 in the places of severe hazard and warehouse hazard.
(2) The number of standard sprinklers controlled by water distribution branch pipes and water distribution pipes in light-hazard and medium-hazard locations should not exceed the provisions in Table 5-1.
Table 5-1
The number of standard sprinklers controlled by water distribution branch pipes and water pipes in light and medium hazard places
| DN(mm) | 25 | 32 | 40 | 50 | 65 | 80 | 100 |
| light-hazard | 1 | 3 | 5 | 10 | 18 | 48 | |
| medium-hazard | 1 | 3 | 4 | 8 | 12 | 32 | 64 |
Common problem 7
Sprinkler location, height, and distance from obstructions do not meet requirements
Causes and consequences: Due to the change of decoration and room size and use, the position of the sprinkler head has changed relatively, so that the spraying area of the sprinkler head cannot meet the requirements of the design specification, and the effect of automatic sprinkler fire extinguishing is reduced.
Prevention measures and relevant regulations: "Code for Design of Automatic Sprinkler System" GB50084-2001 (2005 Edition) stipulates:
(1) Except for the ceiling type sprinkler and the sprinkler installed under the ceiling, the distance between the upright type and the pendant type standard sprinkler should not be less than 75mm and should not be greater than 150mm.
(2) When the sprinklers are arranged on the plane below the bottom surface of beams or other obstacles, the distance between the splash plate and the top plate should not be greater than 300mm, and the vertical distance between the splash plate and the bottom surface of obstacles such as beams should not be less than 25mm and be greater than 100mm.
(3) When arranging sprinklers between beams, they should comply with the provisions of Article 7.2.1 of this code. When it is really difficult, the distance between the splash plate and the top plate should not be greater than 550mm. For the sprinklers arranged between the beams, if the distance between the sprinkler plate and the top plate of the sprinkler reaches 550mm and still cannot meet the requirements of Article 7.2.1, an additional sprinkler shall be installed below the bottom surface of the beam. The vertical distance between the sprinkler head under the dense-ribbed beam plate, the splash plate and the bottom surface of the dense-ribbed beam plate should not be less than 251nm and not be greater than 100mm.
(4) In places where the clearance height does not exceed 8m, and the cross beams arranged with a spacing of not more than 4X4 (m), one sprinkler can be arranged between the beams, but the water spray intensity should still comply with the provisions of Table 5.0.1.
(5) The sprinkler head should be arranged in a position under the roof or suspended ceiling where it is easy to contact with the hot air of the fire and is conducive to the uniform distribution of water. When there is an obstacle near the sprinkler, it should comply with the design specification for the distance between the sprinkler and the obstacle or add a sprinkler to compensate for the water spray intensity.
(6) When there are combustibles in the stuffy roof and the technical inter layer with a clearance height of more than 800mm, sprinklers should be installed.
(7) When an automatic sprinkler system is installed in a local place, sprinklers shall be installed on the outside of the aisle or communication opening that is connected to the adjacent place without automatic sprinkler system.
(8) Where a permeable ceiling is installed, the sprinkler heads should be arranged under the ceiling.
(9) When the width of obstacles such as beams, ventilation pipes, pipes arranged in rows, bridges, etc. is greater than 1.2m, sprinklers should be added below them. If there is a gap above the additional nozzle, a heat collecting plate should be installed.
(10) For vertical side wall sprinklers, the distance between the splash plate and the top plate should not be less than 100mm, and should not be greater than 150mm, and the distance from the back wall should not be less than 50mm, and should not be greater than 100mm. The distance between the splash pan of the horizontal side wall type sprinkler and the top plate shall not be less than 150mm and shall not be greater than 300mm.
Common problem 8
The automatic sprinkler system is directly connected to the branch pipe of the sprinkler on the main pipe
Causes and consequences: The water output of the directly drawn nozzles exceeds the design water output, causing the water output of other nozzles to fail to meet the design requirements, affecting the overall fire extinguishing effect.
Prevention and control measures and related regulations: The sprinkler should reasonably distribute the water output according to the design requirements, and the connection position of the sprinkler should not be changed at will.
Common problem 9
Sprinkler system piping use cores or unions in the incorrect location
Causes and consequences: The pipeline is prone to leakage and damage, which affects the normal fire fighting work.
Prevention and control measures and related regulations: reducer joints should be used when the diameter of the pipeline is changed, and pipe cores shall not be used at the elbows of the pipelines. Pipes with a nominal diameter greater than 50mm should not use unions.
Common problem 10
The valve between the wet alarm valve and the delay switch alarm bell is closed, or the connecting rod of the alarm bell is not flexible
Causes and consequences: When the fire alarm valve is opened, there is no water flowing through the pipe through the alarm bell, which causes the alarm bell to not operate, and the delay switch cannot alarm the fire center, delaying the fire fighting work.
Prevention measures and relevant regulations: The valve between the wet alarm valve and the delay switch alarm bell must be opened, and the connecting rod with the alarm bell must be flexible and normal
