【 Weak current College 】 sprinkler system problems of

«Ò» ¡ ¢ spray pump flow design issues
Designers in the calculation of the flow of the spray pump, usually the first set of spray system for fire hazard class, and then set the level corresponding to the intensity and effects of water, the product area shall be spraying pump design flow. But the design flow is assuming the role of all the sprayer area work under pressure and flow rate is equal to the most negative point the nozzle pressure and flow, ignored the pipeline pressure loss on the influence of nozzle pressure so that the design flow is less than the actual flow. Besides spray system protected areas are usually several floors, fire would like CCTV North with floor of the building's most beneficial or more floors due to high pressure nozzle, spray volume, volume increases, therefore, the system was originally calculated flow is not enough and must be appropriate to expand. In the choose when the spray pump, flow rate should be calculated on the basis of volume multiplied by the factor of safety 1.15 ~ 1.30 to meet fire sprinkler system of the actual water demand.

Second, the nozzle selection problems in the design, construction

Closed water according to its Chief head morphology and installation into hanging-type, upright, ceiling-and wall-type. Hanging-type nozzle has a flattened splash plate, sprinkler, water spilled into the lower part of the majority. Erect-a cup-shaped buckle under the splash plate, sprinkler, 80% of the water down spraying water sprinkling, 20% to the ceiling. Two heads are generally do not need to install in the upper part of the spatial structure of sprinkler protection, but very different from its installation: hanging-type nozzle through Korea's short risers and spray, dry pipe connection; vertical-type nozzle through Korea on short risers and spray, dry-pipe connections. In specific projects, few builders will confuse the two nozzles, which installed upright sprinkler installation of misunderstood as hanging-type nozzle, causing real sprinkler, the vast majority of water cannot shed to the lower part.

Sidewall sprinkler is divided into two types: vertical installed in the side wall of the closed-head, called a vertical wall-type nozzle; horizontally mounted on the side wall, head of the central axis perpendicular to the side wall, and parallel with the ground, called horizontal sidewall sprinkler. Because of the side wall sprinkler nozzle compared to other types of controlled fire area is relatively small, therefore, it is only available for the top surface to the horizontal plane of the risk level and in the light of risk I-room and the Office of protection zones, some designers in hotels, shops and other public places in the design of the spray system also incorporates a sidewall sprinkler. In addition there are some development company-building storey 5.2 meters of roofs of empty office building in the sidewall sprinkler, once the owners to carry out the second decoration will lead to the nozzle has been in the ceiling, which are not consistent with the normative provisions.

3. wet alarm valve group in the design and construction issues

Wet alarm valve group consists of wet alarm valve, water control valves, hydraulic retarder, alarm, pressure switches, filters, water valves, and other components, it bears test test water supply installations and alarm facilities, alarm, drainage and many other features are automatic fire sprinkler systems of important components. But in the specific project, wet alarm valve set design and construction of many problems.

1. wet alarm valve set incorrectly

When building a fire, water spray nozzle movement, the pressure switch should be started as soon as possible of the action in a timely manner, as spraying pump system fight early fire provide adequate water and pressure. Therefore, you should as much as possible to the wet alarm valve setting near the protected area of the site, reduce the length of the distribution pipe. But in large commercial and community building project, designers often wet alarm valve set setting left protected buildings of the pump, the valve after the laying of pipeline buried in outdoor, distance long resistance loss and start spraying pump pressure switch. Import and export of connecting alarm valve control valve must be in an open State, so this valve the valve that should be used in the signal and the signal should be back to the fire control centre kui; when not using signal valve, lock valve position locks.

2, water control valve adopts the General floodgate valve

In order to guarantee the spray system pipe network with continuous water supply, water supply control valve must be in an open state. Therefore, this valve the valve that should be used in the signal and the signal should be back to the fire control centre kui; when not using signal valve, lock valve position locks. But in the specific project, a few designers in the design drawings are not to be clear, some construction units with no signal without lock General floodgate valve.

3. pressure switch signal lines does not meet the requirements of laying

Pressure switch mounted on the hydraulic retarder export-jingling, as long as the delay is full of water, its pipeline pressure reaches the set value, the pressure switch will action alert, its alarm and control signal should be transmitted to the fire control centre and spray pump control cabinet, to the report fire and automatically start spraying pump. Therefore, the pressure switch alarm and control line should wear metal pipe buried into the body; if the downlead, fire retardant coating of metal pipe external application. But in specific projects, few builders not only not laying of lines, and only accommodate to alert the fire control centre are not routed to the line, spraying pump control unit for control line, the result once the fire control centre of alarm control cabinet fails, you cannot automatically start spraying pump. Downlead metal tube not flame retardant coating fire retardant paint. Also some construction unit replaced with electric contact pressure gauge, pressure switches automatically restart, stop spraying pump, does not comply with the spraying pump control only manually outage.

4. hydraulic alarm settings inappropriately

The scientific name of hydraulic alarm is hydraulic mechanical alarm. In wet alarm valve action by valve signal port out of the water, hydraulic drive, issue the continuous alarm sound for alarm. Therefore, water alarm should be located where it was on duty and its vicinity, and alarm valve connection pipe diameter should be not greater than the total length of 20mm 20m. But in the specific project, and construction units tend to be the nearest setting in the unattended pumping or pipeline well, causing the alarm useless.

5, provinceOn the install filter

Because of the delay for inlet diameter and hydraulic alarm only nozzle diameter 6mm and 3mm, can easily be blocked, so wet alarm valve signal port to delay for the pipeline should be installed filters. But in the specific project, since designers tend to design for wet alarm valve group settings area, the specific component is not as described, some construction units installed filters, use some time after the hydraulic nozzle is blocked, the alarm does not function alarm.

4. Design and construction issues flow indicator

1. flow indicator watch area too large

Flow indicator is usually installed at the level of water distribution pipes, water distribution pipe. As long as the spray head movements, networks with water flow, the water flow indicator i.e. actions of the police, the signal transmission to the fire control centre represents an area of water sprinkler head is action. Therefore, in each of the floors or each fire partitions spray pipe located a flow indicator to monitor each building or per nozzle fire partitions. Now building large scale works a lot, often a floor has several fire district, a few design, construction workers are not in each fire zones set flow indicator or use inferior flow indicator, resulting in a fire, a fire sprinkler head movements, not combustion control centre accurate area. In the shelve and roof are equipped with sprinkler warehouse, should also be within the rack and the roof of water distribution pipe flow indicator on the set to the correct judgment of fire. If a wet alarm valve only control a floor or a fire partitions, you do not need to set the flow indicator.

2, with water flow meter action signals directly start spray pump

As the water flow indicator can be water flow status signal is converted to electrical signals, and signals through the modules to the fire control centre, in a specific project, often having a applicator used signal flow indicator of actions to directly start spraying pump. When the network has the unusual fluctuations in water pressure, rather than the nozzle spray, water flow meter of actions will cause the sprinkler pump malfunction, therefore, this boot method is incorrect.

V. eqnipment installation problem

Eqnipment settings in the system the most disadvantageous end inspection system head the most negative point of flow, pressure meets the requirements, and system of alert and water supply device boot functionality. In the specific project, eqnipment installation exists with many problems.

1, eqnipment is not set in the Terminal

The most negative nozzle spray system are often not drainage facilities in the vicinity, a few construction units to nearby drainage from the system of non-terminal access network test water plant, causing no real detection system the most negative point of flow and pressure.

2, eqnipment setting height is easy to operate

Eqnipment of pressure gauge and valve installation highly desirable from the ground, so that operations 1.5m and observation. But in specific projects, the majority of construction to the artistic needs of indoor decoration, requiring construction party will pressure gauge and valve settings in the ceiling or other very high position. At the bottom of the mouth of the end of the test water should be equipped with indirect discharge of funnel and drainage pipes, in order to facilitate the drainage of water, but in specific engineering, and construction units tend to ignore this detail, water, water everywhere, not only affect the operations, and damage to the interior decoration, led to the test water operation extremely inconvenient.

3. pressure gauge set, the control valve upstream from the water hole

As a true reflection of the doctrine of the water pressure and flow, eqnipment pressure gauges should be set in the control valve downstream, close to the water hole. But in specific projects, few construction team will be set in the control valve for pressure gauge upstream, away from the water hole.

6. system network in the frequently asked questions in the design and construction

1. alarm valve after the pipe valve did not use signal valve

Alarm valve of water distribution pipelines usually concealed in the pipe shaft, suspended ceiling, the control valve on the pipeline is difficult to find, once opened after maintenance, to promptly forgotten fire, valve after the nozzle as useless. Therefore, after you set the alarm valve control valve is not appropriate, such as the need to set the time should be used in signal valve, the valve to open and close the status of the signal can be sent to the fire control centre. Example: the flow of control; the indicator reaches civil air defense engineering shower pipe through protective cell walls set when blasting control valve. But most of the design, construction workers ignore this point, using a non-signal valve.

2. system pipe exhaust device is not set on the Internet

When the system memory in the gas pipeline network will produce the following hazards:

(1) the system of gas pipeline network memory in oxygen, with room temperature changes constantly dissolved and separation, on the pipeline to produce chemical and electrochemical corrosion.

(2) pipe top aggregation in compressed air would exacerbate water hammer effect at the time of the pump, resulting in damage to the pipeline and valves.

(3) network gathering air, the water is full of all of the network, when the upper nozzle opening, the first jet spray water, after delays of water sprinkler.

For these reasons, should be equipped with water sewer main risers top level of the water distribution and sewer pipe diameter greater than end 80mm of water distribution set automatic discharge valve of the trailer. When there is water distribution eqnipment on, you can use the unit vent. But in the specific project, set the number of systems of exhaust device is very small.

3. water distribution piping using welding

System with water pipelines in the inner and outer wall hot-dip galvanized steel pipe, should adopt screw, clip, flange connection. A small number of workers for construction of simple, lower cost, the use of welded connections and welded flanged, destroyed the zinc coating, the impact of the weld quality and reducing pipe corrosion resistance capability.

4. system piping through the walls or floor,No additional casing

System piping through the walls or floor, no additional casing, the consequences are: when a pipe or structure changes, will affect each other, resulting in damage. Therefore, it should be in the pipeline through the walls or floor steel casing when installing. Steel casing diameter than the pipe outer diameter large through 20 ~ 40mm. To prevent a fire with fire, casing and piping of clearance should be nonflammable material fill compacted.

5, the laying of the pipeline is not conducive to drainage

Spray system maintenance, to pipeline emptying. In order to facilitate the drainage pipe system must not be less than 2 percent of the slope from SubMain tube slope to distribution mains, water distribution pipe slope to the water mains, sewer water slope with water standpipe way installation. When the nozzle down installation, connection nozzle and distribution pipelines of short standpipe length not more than 150mm, avoid short risers to water and sediment. But in specific projects, few construction units only figure simple construction, water pipe length of short risers often exceeds 150mm, rarely consider the system of drainage problems.

6. pump suction pipe outlet set incorrectly

Spray system for each group of pump suction pipe should not be less than 2. Alarm valve annular pipes before the setting of the system, each pump outlet should not be less than 2. Pump's suction pipe should be set control valves, check valves, pressure gauges and diameter of not less than the test water valve 65mm. But some projects are only water and outlet pipe 1 root and no set of not less than the test water valve 65mm or diameter not 65mm.

VII. system pressurization and facilities in the frequently asked questions in the design and construction

1, regulators pumps flow selection is too large

When the fire water tank set height does not meet the system most negative pressure nozzle, the system should be set voltage pump, booster facilities. Regulators pumps only in fire early, spray pump is not started before the system pressure pipeline network provides its flow generally should not be greater than 1L/s. But in a few specific engineering, design, construction personnel chose to flow a lot of regulators pumps, it is not conducive to the timely launch of the spray pump.

2. voltage pump installed incorrectly

Regulators pumps must install, next to the line for maintenance, there are still in pipeline pressure water supply. But in specific projects, some construction units take online installation, once in the water tank maintenance, to supply water to the network.

VIII. concluding remarks

Wet system is an automatic sprinkler system, the most typical and most universal application of the system. It for control and extinguish the fire in the early days with very high success rate. Therefore, should strengthen the wet sprinkler system design and construction quality control to ensure that the fire mode, the system can play its rightful role in harm reduction and reduction of fire, security and safety of people's lives and property.