High-rise building fire hydrant system, selection

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High-rise building fire hydrant system, selection of pressure reducing orifice plate

Force, and the burden of water cannon, and leave the ground water zone and the quality of the water column, usually around 5kg, force direction vertically downward. The firefighters trained reaction force can withstand water gun is generally 147N, the maximum can not exceed 196Nl3]. Reaction depends on the pressure of the water hydrant port, through a simplified formula derived can be drawn from the DC hand-held water gun in the jet reaction force generated when the formula for the F-2WrP (7) where, F is formed when the reaction spray gun force; W cross-sectional area for the gun nozzle; P for the gun nozzle pressure. Water gun water gun nozzle pressure and the relationship between reaction force, listed in Table 2] Table 2, the nozzle pressure water guns and water guns water guns mH2O reaction to enrich the relationship between the length of the water column pressure water gun water gun nozzle reaction force / N74.9783.4094 .37113.88135.24150.04180.52197.27238.92 Note: 1mH2 【】 a 9.80665Pa. Know from Table 2, when the pressure is 35.5mHO gun nozzle, the water gun reaction force greater than 196N. 196N using water cannons into the reaction method, by (2) and (3) water gun nozzle injection flow rate Q for a 7.46L / s; H === 41.252mH2O visible, fire hydrant plug port for the maximum allowable pressure 41.252mH20. 2.3 Selection of decompression and decompression orifice check the value of (1) water pump selection pressure reducing orifice plate conditions. Hydrant plug port to the maximum allowable pressure 41.252mHO on the line as the vacuum value, can determine the condition of water supply pump 7 to 1 layer needs to decompression; tank water level conditions to be 3 to 1 decompression. Therefore, in order to determine the condition of water supply vacuum pump level (7 to 1 layer) and the vacuum value and the primary orifice models. H-H-41.252 (8) where, H is the value of each layer of the theory of relief; H to pump water pressure when the hydrant plug port. Orifice head loss by (4) calculated: from (4) and (8), can be obtained 6 to 1 layer of fire hydrant in front of the short branch of the theory of decompression orifice plate impedance factor S, then according to selection theory of decompression orifice plate S ≥ S, and orifice close to the principles of the latter selection, the specific selection of Table 3, in l6j. Table 3 decompression orifice selection mH2O Note: in this case S-/, where Q is 11 ~ l layer message after the fire plug port traffic to 5.83L / s for the simplified calculation. Can be seen from Table 3, pump water decompression is less than the remaining head conditions, and after decompression fire hydrant bolt saliva pressure of less than 41.252mHO, indicating decompression pump water conditions both fire hydrant pressure bolt saliva can achieve the full requirements of the water column less than the maximum pressure fire hydrant bolt saliva 41.25mHzO. Therefore,[link widoczny dla zalogowanych], the selection of plates for the condition is appropriate. (2) the value of tank water conditions check decompression. Tank water supply conditions, the vacuum is less than the remaining bolt head and the fire hydrant after decompression saliva pressure of less than 41.25mH. O, that after decompression tank fire hydrant water supply conditions tied to both saliva pressure is greater than the minimum water pressure tank water supply conditions allow 7mHO requirements, but also less than the required fire hydrant bolt specification maximum limit 50mHzO saliva pressure , orifice of the conditions for the selection is appropriate. 3 Conclusion (1) the generation of residual head and size of fire hydrant system, water supply not only the way of water supply and water supply system is closely related conditions. (2) shall be calculated in order to pump water decompression condition decompression calculation value and the plate model, then check the water tank for water supply conditions, which finds relief orifice models. (3) In order to facilitate fire operations, fire hydrant at the conditions of pressure relief devices should be designed to 41.25mHzO for the sector, that is, when the fire hydrant water pressure is greater than the mouth of the 41mH. O, the fire hydrant at the pressure relief devices should be established. [
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