【 Weak current College 】 fire hydrant protection RADIUS discussions

About fire hydrant protection RADIUS, we all have lots of ideas, norms which gives the calculation method, but many people in the application of methods and no, I am here to talk about specific calculation methods, there is no good place for hope to correct me.
First we see the architectural design fire protection standard "GB50016 — 2006 (hereinafter referred to as buildings》) mentioned in section 8.6.2:
2. the arrangement of indoor hydrant, should ensure that there are two pistol at the arrival of the full water column indoor any part. Building height less than or equal to the time and volume 24m is less than or equal to the Treasury, 5000m3 may use the full water column 1 pistol reach indoor any part. Nozzles full water column length should be determined by the calculation, generally should not be less than 7m, but a, b building, more than six layers of civil architecture, more than four layers of the plant and warehouse, should not be less than 10m; senior industrial building, elevated coffers, nozzles full water column should not be less than 13m water column;
We consider whether it is a water gun or pistol at the arrival, you first need to determine a water gun range is large, according to the fire hydrant protection RADIUS calculation formula:
R=kLd+Ls
Where r-fire hydrant protection RADIUS, m.
K------fire hose of the reduction coefficient, taking 0.8 ~ 0.9
Ld--------fire hose length.
Ls--------water gun full water column lengths in the plane of the projection length, m, when the water gun dip as α, Ls = c k o S s α
The length of the full water column above Sk = (H1-H2)/s I n α
Including H1-------indoor most high fire point height, m above the ground,
H2-------gun nozzle height above the ground, usually from 1 meter.
Α--------water gun, normally on an angle of 45 °, the maximum should not exceed 60 °.
Sk formula in accordance with the calculation of manual selection, buildings》 has been simplified in the formula, to:
Sk = H-storey/s I n α,
Consider the relative in the manual, it is reasonable to still use the manual calculation formula.
In the lists above formula, we began to discuss the value of preceding hose length, and the reduction factor, buildings》 in recommended 20 m long hose, but now designers use 25 m hose, and more generally, we present discussion or in 25 m hose as examples.
The following look Ls calculation, first consider the calculation, Sk, for calculations of example 1 is a powerhouse, and a height of 10 meters, the full water column calculated Sk = 14.1 m, because greater than 7-story building requirements, uses 14.1 m m, example 2 is a high-level Workshop-5 m, the calculated Sk 7.07 m less than the standard requirements of 13 meters, with 13 m.
See the specifications of calculation, we specifically to discuss specification later in this second example, we should follow the calculation is to compute the protection 7.07 metres radius, or follow the 13 m to calculate our protection RADIUS, this specification does not explain, if you calculate according to 7.07 m, then protection radius should be:
R = kLd + Ls = 0.8x25 + cos45 ° x7.07 = 20 + 5 = 25 m
If you calculate according to 13 metres, then protection radius should be:
R = kLd + Ls = 0.8x25 + cos45 ° x13 = 20 + 9.2 = 29.2 m
The difference between the two, it is clear that the 4.2 m difference is very big, but we can clearly see the direct selection of 13 m to calculate is problematic issues? is the standard assumption of 45 °, 13 metres of water column simply spray is not so high because the water was floor block, you should follow the 7.07 m to calculate the? no, because we actually chosen is 13 m full water column, then we need to consider in 13 feet of the specific usage of the fire hydrant, there's a selection of α angle, the angle α if we choose smaller, then obviously the water projection will be larger, we can assume that the calculations, the enrichment of the water column 13 meters arrive exactly when alpha angle slab, should have the equation:
Sinα=(H1-H2)/Sk=(5-1)/13≈0.31
So: α ≈ 18 °
At this point, the fire hydrant protection radius should be equal to
R = kLd + Ls = 0.8x25 + cos18 ° x13 = 20 + 9.2 ≈ 32 m
You can see that this should be a true computing protection RADIUS.
Above we discuss is the ideal case, that is, it does not consider the obstacles blocking the inside buildings, in the actual design we should consider a lot of problems, because we know if our water gun cannot pull the door of the room, or hallway in the corner, even if the enrichment of the water column and then water gun, nor to ignition point, so we should also talk specifically about water gun itself able to arrive at the location of the problem.
To discuss this issue, we have to go back and look at the front of the fire hose of the reduction coefficient k, code inside it value is 0.8 ~ 0.9, consider building aisle bending and Occluder many situations and building a few obstructions of the void between the plane of complex value from small, simple, Max value multiplied by the coefficient hose length k is considered the true length of the hose, there is a place of chart company allegedly under fire departments in the water with length x coefficient k before you subtract 1.1 m height, the point I think lack of normative basis for support, I do not agree.
In the calculated belt length available water, we come to discuss specific layout issues, in factories, warehouses, underground garage, and other large open areas, we can consider the protection of RADIUS circle to check whether you can meet the requirements of the two pistol, but if you're on a more complex construction there should be specific to consider every gun according to specific travel routes to reach the location considerations, especially considering the water gun itself able to arrive at the location of a dead ends, and so on factors, there is need to consider some places when unable to pass through the fire, such as both sides cannot pass through the door of smoke staircase, etc., in order to take into account that water gun layout of is to compare the actual and reasonable.
To sum up, we can see some of the designers in the layout of the fire hydrant, does not take into account the specific circumstances, in accordance with 28 m radius of protection or the protection of 25 m radius for laying out fire hydrant, and only used to draw a circle to check meet the requirements of the two water gun, there is a problem, you should analyze specific circumstances, in order to achieve reasonable design.