I. Water source problems and rectification measures:
There are two main sources of water for direct sprinkler systems:
Normal high-pressure water supply method directly connected to the municipal pipe network; temporary high-pressure water supply method using a fire-fighting pool plus a fire-fighting pump. The auxiliary water source facilities include a roof fire-fighting water tank and a pump adapter.
The common problems and rectification measures of these facilities are as follows:
1. Improper installation
(1) When using the normal high-pressure water supply method directly connected to the municipal pipe network, a common problem is that only one inlet pipe is provided. Such a design and installation method cannot effectively ensure uninterrupted water supply to the system.
(2) Rectification plan:
An additional introduction pipe shall be provided, and the requirements of one use and one preparation shall be met, that is, when one of them fails or is overhauled, the other one can still pass the entire firefighting water consumption. At the same time, the two inlet pipes should be introduced from different pipe sections of the municipal pipe network to the greatest extent possible to ensure that the system's uninterrupted water supply can still be guaranteed when the municipal pipe network fails or is overhauled.
2.Spray pump cannot guarantee stable and effective operation
(1) When the temporary high-pressure water supply method is adopted, the spray pump becomes the "heart" of the entire system. There are two common problems during inspection:
① The dual power supply switching device powered by the spray pump control cabinet has only one circuit for normal power supply. When this circuit fails, the backup circuit cannot actually be put in, and it cannot really guarantee the uninterrupted power supply of the spray pump;
② The spray pump control cabinet is not locked in the "automatic" state. This error operation is so simple, but so fatal that it will directly cause the fire alarm controller to fail to start the spray pump in conjunction with the fire control room remotely. Start the spray pump.
(2) It is very simple to rectify such "minor problems" that directly affect the function, but once found in the supervision and inspection, it must be strictly investigated, otherwise it will not cause the offenders to pay enough attention, and will eventually be caused by "minor problems" "With serious consequences.
3.Municipal water supply is not effectively used
(1) There is also a general problem when using temporary high-pressure water supply, that is, the sprinkler system and indoor fire hydrant system only rely on fire water pools and fire pumps to supply water, and no longer connect to the municipal pipe network. The current national regulations do not make this clear.
(2) Even if the mode of temporary high-pressure water supply is selected, the two systems should still be connected to the municipal pipe network. This connection scheme has two benefits:
① It is easy to realize, there is a water inlet pipe of the fire water tank next to the fire pump room, just take it over;
② As a very reliable backup water source, the municipal pipe network is the best choice. After the municipal water supply is connected to the indoor fire pipe network, the fire protection water supply of the protected building is added to the first level of protection within the effective common supply height of the municipal water supply pressure. . The connection part of the indoor pipe network can be selected on the ring network behind the hydrant pump and sprinkler pump outlet pipe. The automatic sprinkler system should be connected to the small ring network in front of the wet alarm valve.
4.The roof fire water tank cannot operate normally and effectively
There are four common problems with roof fire water tanks and their boost and pressure stabilization facilities:
(1) No heating facilities are set up between the water tanks, which may affect the normal operation in winter;
(2) The booster pump control cabinet is not locked in the automatic state, the electrical contact pressure gauge is damaged, or the working pressure range is set incorrectly, which will directly cause the booster voltage regulator to operate normally and effectively;
(3) The small one-way valve of the boost pressure regulator device is prone to failure due to inadequate sealing. The valve returns to the water, which will cause the booster pump to start frequently, which will cause damage to the electric contact pressure gauge and the booster pump;
(4) The booster pump generally uses a dual power switch with the roof fan and fire elevator. The switch box often has only one circuit for normal power supply, which does not guarantee uninterrupted power supply.
5.Water pump coupling is easy to be buried pressure, poor management and maintenance
Common problems with water pump adapters are:
(1) It is easy to be buried. The underground pump coupling is always habitually installed in the parking lot of the front and back yards, and it is easily buried. During the construction inspection, the setting position should be taken as an important content, and the construction unit should be urged to be installed in a place that is not easily buried. If the construction has been completed, it is necessary to formulate and implement a system for prohibiting buried pressure in management.
(2) The maintenance cannot be carried out on schedule, and the valve is closed. Some pump couplings have not been maintained since acceptance. Therefore, at least once a year, the water supply test of the fire truck should be performed during the supervision and inspection.
Problems and Corrective Measures for Wet Alarm Valves
1.The ball valve is closed
(1) The small ball valve on the pipeline of the delay valve behind the valve flap of the alarm valve is often closed. This "small problem" is as serious as the control cabinet of the pump is in the "manual" state. It will cause the pressure water to enter the delayer after the valve flap is opened, resulting in the hydraulic alarm bell and pressure switch not alarming. The direct consequence is a fire alarm The controller cannot be started in conjunction with the spray pump. The main reason for this problem is that the equipment management staff did not really grasp the working principle of the wet alarm valve. When seeing the other small ball valves are closed, this critical small ball valve was also closed at the same time.
(2) Effective measures.
① The wet alarm valve must be checked for each inspection, and the person in charge of maintenance must talk about the working principle of the wet alarm valve.
②Hang a very eye-catching warning sign "The valve must be open!" On the small ball valve, and include the small ball valve in the daily inspection. There is a small filter at the rear end of the small ball valve, which will cause the same result if the filter is clogged. It should be cleaned regularly.
2.A small hole throttle valve is not installed under the delayer.
This is a prone problem. Instead of installing a small-hole throttle valve, it is directly connected to a steel pipe, which causes the amount of water flowing out of the delayer to be too large, and the actual delay is too long, which causes the drain valve to start discharging water. For a long time, the hydraulic bell and pressure switch did not alarm. This issue is relatively frequent and should be the focus of inspection and supervision.
3.The installation position of the hydraulic alarm bell is wrong
During the supervision and inspection, it is often found that the hydraulic alarm bell is installed next to the wet alarm valve, instead of being installed in a place that is easy to be heard by the staff (especially the duty staff), causing the hydraulic alarm bell to become a deaf ear. This problem is also more frequent. Fire pump rooms and wet alarm valve rooms are not required to be on-site for 24 hours. It is difficult to hear the hydraulic alarm bells set in these parts after the ringing, and the original purpose of setting the hydraulic alarm bell is lost. significance.
This problem will not cause the entire system to malfunction. When the alarm sound of the hydraulic alarm bell is not heard, there are still alarm signals such as pressure switches and water flow indicators that will be reported back to the fire control room, but it should also be supervised strictly.
Should be required to choose a suitable installation location of the hydraulic alarm bell, while its connecting pipe should be selected DN20 internal and external hot-dip galvanized steel pipe, the length of the connecting pipe should not exceed 20m.
4.There is no water accumulation and drainage facilities near the wet alarm valve
(1) The wet alarm valve installed in the pump room shows no organized drainage measures such as a puddle, a drainage ditch or a drain pipe. Each time a discharge test is performed, the small hole in the drain pipe, the delayer and the hydraulic force The outlet pipe of the alarm bell was drained by the three drainage pipes at the same time, which caused water splashes under the drain pipe and the entire floor of the pump room. Water was often splashed on the test personnel's clothes and wetted by the test personnel's shoes and socks. Bleed linkage test.
(2) When multiple buildings share the fire pump, some protected buildings are far away from the pump room, and a special water supply pipe is led from the outlet ring of the spray pump, until a special wet type is installed in the lower part of the protected building. Alarm valve valve well chamber, but no drainage facilities are made in the valve well chamber, which makes it impossible to conduct daily inspection through the discharge test.
3. Problems and correction measures of end-of-water test devices and water test valves
1.The position of the end water test device and the water test valve is not reasonable.
(1) The main problems are as follows:
① The related devices are installed in the bathroom and rely on the floor drain for drainage, which causes the overall drainage of the floor in the bathroom, and it is easy to splash the testers' clothes and socks;
②Some end water test devices and water test valves are installed in the linen room of the hotel or in the storehouse after the mall's paving, and cannot be used as drainage facilities;
③ Some valves and pressure gauges are set too high or even installed in the ceiling, which is very inconvenient to operate. These problems will cause the maintenance staff of the unit to fill in the form and not test, which will cause troubles in normal and effective water discharge tests.
(2) Specific requirements for rectification:
① The terminal water test device and water test valve should be set at a position and height convenient for operation and observation by personnel;
② An organized drainage facility with sufficient drainage capacity should be provided. For example, a water test device can be installed on the outer wall of the same axis on each floor of the building, and a downpipe similar to a rainwater pipe can be installed on the outer wall. The water discharged from the device is discharged into the downspout. A pool should be set in the middle of the mall with a large single-layer area. The volume of the pool should not be less than the displacement of one test. A large floor drain should be set at the bottom of the pool. .
2.The test water connector and pressure gauge are not installed.
(1) Some problems remaining during construction and installation will also be found during supervision and inspection:
① The terminal water test device does not meet the requirements of simulating the action of a sprinkler in the way of small hole outflow. The main performance is that the test water joint is not installed, but the steel pipe is directly drained by DN25. The requirements of Article 6.5.2 of the Code for Design of Sprinkler Systems (hereinafter referred to as the `` Spray Regulations '');
② Install the pressure gauge in front of the shut-off valve, which does not comply with the provisions of Article 6.5.2 of the “Specification of the Spray Regulations”. The reason for this reverse installation is that if the water test joint is not installed, After the shut-off valve, the pressure gauge shows zero during the water discharge test.
(2) The focus of the rectification measures for this problem is to install water test joints, and then change the positions of the pressure gauge and the stop valve.
3. The design requirements of the "water test valve" are low
(1) "Spraying Regulations" stipulates that the terminal water test device and its components are set at the most disadvantageous nozzle, while other locations only require the test valve, and the flow coefficient and the discharge coefficient of the test valve are not tested for water discharge. Stress tests do specific requirements. From the perspective of engineering practice, such regulations have very limited cost savings.
(2) Measures should be taken:
① The concept of "water test valve" should be cancelled when the code is revised, and the end of each water distribution pipe should be provided with a terminal water test device;
② For buildings that have already been put into use, fire supervision personnel should require each test valve to do the test of the terminal water test device when conducting fire supervision and inspection, especially for a certain person located in a large part of a building. In dense places, each of its water test valves should raise the standard to require.