【 Weak current College 】 sprinkler system design several important issues in the

1 nozzles

Rational arrangement of the nozzle is automatic sprinkler system design is the key to security and economy. Comparison of the spray regulation law emphasizes role of water in the area of strength and sprinkling of uniformity and nozzle opening time. For each nozzle of RADIUS, and the manufacturer's product and technical parameters for, and the location of water sprinkler, third, and the layout position the nozzle (structure column and the impact of various barriers). Control of the spray nozzle spacing provided only a "limited", in order to better guarantee the Jet spray intensity and uniformity and timely open.

1.1 sprinkler layout principles and requirements

(1) meet the role of water in the area of strength, sprinkling of uniformity and nozzle opening time (head heating conditions and opening hours);

(2) Nozzles spray RADIUS in flexible layout, there is no white space is not overwritten, it does not appear excessive important coverage;

(3) ensure Jet wet wall and a range of wall;

(4) nozzle should not influence each other between;

(5) according to the specifications and the actual processing of the obstacles blocking, and positive and relevant professional coordination;

(6) should meet other relevant norms of nozzles;

(7) considering the fire plume flow on effect of nozzle movement;

(8) practical, comprehensive analysis of the relevant specification: eat deep specification wording.

1.2 Nozzles spray RADIUS and

Water spray RADIUS is the main basis of nozzles, which represents an economic value, while working in the nozzle does not appear blank is not overwritten, it does not appear excessive important coverage. It and risk level of the water jet strength, character and working pressure nozzles. Engineering design of nozzles depending on the architectural plan, in spray RADIUS range, flexible use of square, rectangular or square shape. Water spray RADIUS is different from the head of the RADIUS, which is calculated on the basis of the RADIUS, consider sprinkling strength, water heating uniformity and sprinkler condition and timely open, according to the norms and values. Specific see table 1: as the main layout is affected by other factors, the larger, often occur nozzle does not follow a fixed distance to the layout, not to mention the same buildings often does a spacing of cloth, that is the same layer, are often the same fire partitions. In addition, as a civil engineering design, different in the decoration design, you need to leave a second decoration, nozzle spacing is not appropriate to press for maximum distance requirements set, but in practice it is difficult to meet the regulatory requirements of water sprinkler strength and uniformity.

Design must be based on actual projects, by design the selected water jet strength, nozzle flow coefficient, work pressure, and considering sprayers in heated conditions and opening hours, in meeting the specification requirements of nozzle strength conditions, press the actual working pressure nozzles, combining architectural separated and structure column flexible layout. In the layout, nozzle spacing should not be a fixed number, should be based on the location of the conditions to be ensure that the ultimate goal or water-jet strength and uniformity and timely open.

1.3 should not interpret collector plate

The Jet set of governing law on the hot plate, see 7.1.7 bar, it is for a shelf made of nozzles, the Jet set of thermal regulation is referred to as stalls water board. When the head above the hole and slot, to prevent the nozzle for hot air does not over or upper nozzle spray cooling not booting, provisions should be above the nozzle set hot-plate. Also, the garage, garage, parking design fire protection standard "[2] in 7.2.3.2 stipulates that the machinery garages, duplex garage parking by pallet location hierarchical arrangement of the nozzle should be set above which sets the hot plate. And in engineering practice, collector plates used goes well beyond this to have been in more occasions been deductive, but this practice is not normative, but also often defeats with the settings. According to the United States FM company study results show that the nozzle actions required more than 80% of the calories come from thermal convection, and delivered to the nozzle of the convection heat needs hot air flowing through the nozzle to complete. If a fire point of not being on the nozzle, increase of thermal convection in the collector plate like a flip of the box, blocking the flow of hot air iron levels, a fire in the head office to create an air flow in dead ends, but response time delay of the nozzle. Thus, to set the settings of the hot-plate and its inversion, should give careful consideration to, and should be based on existing specifications, combining the actual conditions of argumentation.

2 hydraulic calculation

Hydraulic calculation determines the quantity of water into the fire extinguishing system and fire-fighting water distribution, is a relationship system reliability, rationality, and economics of an important design element. According to the understanding of the spray regulation and a large number of relevant information and analysis of some project examples that use hydraulic calculation should be "rectangular area-by-point", that is, first of all determine the most adverse effects area location in the network (if necessary, by a hydraulic calculation determines), the role of the area of a rectangular shape, it is appropriate only in function of the area included in the calculation of its amount sprinkler nozzle; the most negative after the selected route, using node flow method is the most disadvantageous effect area within each nozzle pressure value and the flow of a find, when two branch interchange, according to the two branches of the pressure difference on pressure higher branches flow correction, and effects of area after flow correction after all the sprayer out the flow of the sum as the sprinkler system design flow, in this segment that flow in the future no longer increases, the only calculation along and local head loss, has always worked to pipeline starting point.

The actual fire occurs, generally the fire source point radiate outward expansion of the epidemic, and only the fire area at the top of the head will open. Therefore adopts the role of area protection and only in the role of the area within the amount of water sprinkler head is calculated to be reasonable. At the same time as the fire effects of convection and windThe role of the area of rectangle shape to a more rational, and rectangular area when the pipe hydraulic calculation is also the most disadvantaged. This rectangular area-by-point method "in line with the actual fire, scientific rigour, and integration with Europe and the United States and other countries, is reasonable, safe, and the spray control law recommended practices.

(1) determination of the rectangular area: effect of the shape of a rectangular area, it is appropriate in the long edge parallel to the water distribution pipes, its length is not less than the effect of an area of the square root of the number of nozzle 1.2 times, if the decimal to carry into an integer. When the distribution branch of actual length is less than the length of the computed value, the function of the area you want to extend to the adjacent water distribution pipes on the nozzle.

(2) economic flow velocity and pressure the most negative point

① economic flow velocity:

Automatic sprinkler system main components are equipped with water pipes and water pipes of diameter, not only affect the overall system cost, more related to the system of fire security. Determine the flow, the flow is determined by the diameter of the important parameters. Use economic flow velocity is the basis for the design of water supply systems, production, domestic water supply pipe flow generally use economic flow so that the pipeline infrastructure investment and the ongoing operating power consumption is optimized to match. The so-called economic flow velocity is an investment and recurrent costs and hours of flow velocity for the economy, while the corresponding to the diameter of the tube diameter for the economy. Why choose water distribution pipe diameter size involves investment and consumption of size, diameter large infrastructure costs are high, but the province electricity, pipe diameter small time investment, but head loss, pump lift high, high tariffs.

The spray control hydraulic calculation in section 9.2.1 pipeline also provides "pipe flow velocity use economic flow rate, if necessary, less than 5 m/s, but should not be greater than 10m/s". However, the flowing water pipeline was only for a short period of time in case of fire, different from the production, domestic water supply pipe is always running at the branch, so you can improve the speed, decrease the diameter to reduce investment in infrastructure, which also is the economy. But if a sprinkler system in higher water flow rate, head loss, the larger distribution mains branch pipe diameter tend to be relatively small, resulting in the design flow, head of physical protection area may not meet the specifications for the role of the area. At this point, although the role of area sprinkler action, its average Jet strength-of-compliance, but because of the pressure on downstream nozzle flow with different but is different, moreover, because of the small diameter of pipe, pipe head loss, fire pump lift high the nozzle spray very uneven, its water discharge inevitable, will prematurely expire fire water storage. Thus pipe velocity use lower values, pipe diameter hour especially the use of low value.

At the same time, also from the above analysis is not difficult to see that the spray control law in economic flow should be economical, rational, reliability and safety of unity, not be used in the sense of economic flow velocity (but its provisions and its description is not involved!). Combined with engineering calculation example of the manuals and documentation describes [3-6], with water pipes and water pipes design flow generally should not be more than 3.5m/s, common 1.8-2.8m/s. This approach to better meet the spray regulation on table 5.0.1, table 5.0.5 and relevant role in 9.1.4 space and water jet strength, and water distribution network head loss is small, the head of fire pumps, nozzle outlet inhomogeneity of smaller, fire water storage capacity can be reasonably used, is a relatively safe, economical and reasonable. ② the most negative point pressure: most disadvantageous pressure usually 0.1MPa, minimum should not be .05mpa. In the past we used to think 0.05MPa for roof height is often difficult to meet the most adverse nozzle pressure value which, in the fire control pump, booster facilities lift your calculations, this problem does not exist, have to take 0.1MPa, but in fact not the case, or even can be said for certain types of sprinkler systems, according to the current specifications, should generally be taken 0.05MPa instead 0.1MPa. We all know that, because of the underground garage of nozzles, first press the spray control of hazardous class ⅱ, should be set above the parking, the three column layout structure is subject to the restrictions and other Eclipse and its handling of the nozzle is generally much more compact layout, and then press calculate 0.1MPa, one is the design value is large, can reach 40L/s (not including the protection of water cooling water), the loss is too large, pump lift is too large, the appropriate height of the water tank. So think for such as underground garage such nozzle to layout overpopulated system or occasions should take 0.05MPa, and this will better meet current requirements.

(3) the system design flow calculation and branch pipe flow correction

① system design flow, the most negative point for area consists of the jet nozzle at the same time, the formula is determined, see the article spray regulation law 9.1.3. Different spray nozzle spacing pipe network because, network size, layout, etc., pipeline spray system of total water consumption and water not uniformity may have greater differences, and spray pipe network actually exist sprinkling non-uniformity, the total consumption of water sprinkler system should be carefully determined otherwise hydraulic calculation, as determined by the spray pump model is likely to be inappropriate, system reliability, rationality, and economics are not guaranteed.

System design for flow calculations in the processing and requirements, see the spray regulation law section 9.1.4-9.1.9.

② two segment intersection calculation pressure, should be-(1) to the intersection point of the low pressure side of the pipe flows.

Type, q1--low pressure side of pipe fixed flow (L/s);

Q2--low pressure side of pipe fixed flow (L/s);

H1--low pressure side of the pipe pressure (KPa);

H2--high water pressure side of the pipe pressure (KPa).

(4) piping along and local head loss per metre pipe head loss calculation-see section 9.2.2 spray regulation law, local water pipeHead loss, the use of equivalent length calculation, will flow through the bends, t-tube of partial pressure loss-similar to a certain length of straight pipe. The actual calculation, often using pipeline specific resistance and the concept of flow coefficient, the local equivalent to the corresponding sections of the pipe length, use EXCEL to complete branch pipe calculation, or a system of calculation (calculation for systems involving the flow correction, to develop the corresponding macro to automatically start the output, you can take to do it manually adjust the fixed work).

(5) pump lift or System Portal water supply pressure

Pump lift or System Portal of water pressure-see section 9.2.4 spray control law, which varies with the original specifications and requirements for wet alarm valve, flow indicator evaluates to 0.02MPa (this calculated value greater than actually!).

(6) vacuum and pressure relief measures

The spray regulation article 8.0.5 article "... Water distribution pipes for water distribution, should allow the entrance of the pressure equalization. Light hazard level, the risk level in the various places of distribution mains inlet pressure is not greater than 0.4MPa "and automatic sprinkler system, not only the existence of lower water pressure in the piping system is not balanced, even in the same layer, when protection area is large, due to a design is the most disadvantageous work area calculation, in favorable work area-location within the nozzle pressure there is residual, so get used to the work area of the connection enabling distribution mains or distribution dry pipe be decompression, and decompression methods can be used to set the pressure relief valve, vacuum tube orifice, throttle and narrow the favourable face water distribution pipes of diameter and other methods to increase along the head's loss to decompression.

Relevant provisions and calculation of the spray control "section 9.3.1-9.3.5.

3 fire water tank and pump adapter

3.1 fire water tank

Water conflicts mainly in the reliability of the power source, the contradiction of exposure in the water system, but a wide range. Related specifications; by building classification using electricity power supply or secondary level with diesel engines ", temporary high pressure to the system should be set fire water tank, etc. China's current water-proof technology specification on fire water tank, the existence of such a negative top and distal parts undervoltage the fire water tank on these negative sites cannot play its role, and in accordance with the regulations of law [8] provisions set by the water pressure, due to the relatively small also failed to properly resolve the problem. Automatic sprinkler system for extinguishing a fire in the early days, the action in the nozzle, the fire will be a few kW per second to 10 kW at the rate of growth, this time open nozzle if not by the strength of continuous water injection, system performance will be significantly reduced, or even to fire into the rapid combustion phase to advantage, its results will result in a fire of fire beyond harder to control fire-fighting capability of the system [9]. To ensure open and continuous spray nozzles, and ensure that disadvantaged parts of the timely and effective extinguishing the fire, the spray control section 10.3.1, 10.3.2, "adopting temporary high pressure water supply system of automatic sprinkler system, set the high fire water tank water should be in line with existing provisions of the relevant national standards. Fire cistern, should satisfy the system is the most disadvantageous point minimum working pressure sprayer and spray intensity. "," Building height not exceeding 24m, and press lightly dangerous level or risk level places in the warm system, dry system or preaction system, such as high water do have difficulty, you should use 5L/s flow-pressure water sharing equipment supply water. "early 10min

This can make the following considerations:

(1) set the fire water tank (pressure water sharing equipment) is intended to: 1 use bit difference as the system provides accurate status of the hydraulic pressure to achieve the tube filled with water to maintain a certain pressure; the second is to provide the system starts the initial water consumption and water pressure in the pump or mechanical failure due to power the normal running of the emergency cases of emergency water supply, make sure that the nozzle orifice opening and immediately after first opening of the early fire sprinkler extinguishing, provide maintenance of water sprinkler, 10min control initial fire forces and to gain time for fire fire brigade reinforcements. 

(2) a temporary high pressure water supply system of automatic sprinkler system, where more than 24 tall buildings or other serious risk level and the risk level for building the warehouse should be set high water tanks, and not available pressure water sharing equipment replacement. Due to the potential difference of water tank water supply, the system of water spray, thus insufficient strength will undermine the system of control fire-fighting capability. For this reason, the requiring fire tanks meet the water supply negative floor and part of the minimum working pressure nozzles and nozzle strength.

But separate settings regulators pumps, only the system regulators and can not provide fire extinguishing water early. The provisions of the regulations of law in that setting in the description of turbocharging facilities aimed primarily at the beginning of the fire, the fire pump Preboot, meet fire sprinkler system pressure requirements. On the booster pump, its water discharge should meet a sprinkler system of water sprinkler. To adjust water pressure tank to its capacity to five of water sprinkler 30s, 5 × 1 × 30 = 150L. The current national standard Atlas-fire pressure regulator device selection and installation (98S176) is based on the doctrine of Napa, its function is merely the early settlement of fire, the fire before the main pump start, make sure you have sufficient storage capacity of fire pressure for early 30s fire until the fire main pump start-up full load. For combined fire water tank pressurization facilities, capacity can only be 450L in emergency situations to 3 only insufficient supply of water sprinkler 2min (3 × 1.33 × 120 = 479L).

Visible for previous roof tanks and regulators devices combined work is not meeting the requirements of regulatory-, and high water tank in architectural design for a variety of factors and it is very difficult to achieve.

To this end the spray Control Act lays down the minimum working pressure 0.05MPa requirements. But in the end is static or dynamic pressure, specification does not enforce interning, this design has brought a degree of difficulty of the same into a certain degree of flexibility.

In fact, 0.05Mpa is the dynamic pressure instead of static pressure. 0.05Mpa refers to the system most unfavourable point the nozzle minimum working pressure, at the same time specification in section description of the middle finger? quot; If the top most negative point the nozzle pressure requirements for 0.1Mpa, the roof must be higher than the top floor nozzle, 10m will give more than the architectural appearance and structure processing has caused great difficulties. In the light of the foregoing and the reference code for foreign related, most unfavorable nozzle pressure identified as 0.05Mpa ".

(3) the height of the upper water tank, buildings》 [10] provides the highest located in buildings (buildings》 document feeder also has static 0.07Mpa requirements), the resistance of the Act requires that the top fire hydrant 0.07Mpa of hydrostatic pressure. If building storey 3m considerations, most unfavorable fire hydrant, upper 0.07Mpa on flowing around just 0.05Mpa hydrostatic pressure. As with the relevant specifications meet the coherence actual engineering design, when the tank is difficult to meet the requirements of the dynamic pressure 0.05Mpa, power reliability, management in place, to consider 0.05Mpa static pressure are also possible.

(4) high water settings guarantee 0.05Mpa dynamic pressure, taking pressure regulator unit, you'll have water tank frame is high. As the tank water to the alarm valve, flow indicator before reaching the most adverse nozzle, tube money longer, even if the fire early, flowing water consumption is very small, there is a certain degree of head loss, specifically to determine the detailed calculation. But generally higher 7m (the height slightly more processing on the building it is able to meet: the thermocline + elevator room + tank pad high) above, you can meet specifications. (In accordance with the rules of Jet-related provisions of the existing standard, wet alarm valve, flow indicates Lu local head loss value is obviously too high 0.02MPa, at least in the calibration tank height is much smaller than this!).

In addition, you can use to narrow nozzle spacing, increase the diameter reduction of losses and other measures to meet the most negative point the nozzle in the minimum working pressure (0.05Mpa) strength of water.

(5) the provisions governing law 10.3.2 spraying of 5L/s, 10min fire storage of pressure water sharing equipment, use of the diaphragm-type pressure tank, from ordinary 2 1 vertical or horizontal. Vertical's optional 91SB3-132 SBQL1600× 1.5 in two. System about 35m2, price about 3.2 million. Some people are having this debate, but considering that new specifications compare stresses fire extinguishing system in the early days, the emphasis in the fastest time possible in the water, and fire people accustomed to the power of thinking, to increase security, reduce the portion of the area, increasing the number of cost is reasonable, justified, as the economy continues to improve safety issues will become more and more attention, at the same time, with the continuous improvement of economic conditions, facilities and help engineering. In addition, taking into account article buildings》 8.8.5 "fire fire pump shall be started within 5min after and after a power outage is still properly. "And" peer review, "sending jiangui 8.7.9" as far as the fire pumps, fire pumps, after the automatic restart after a power outage and still properly "jugs of water can under buildings》 press 5min, value. But I personally believe that, although the water pump of Kai-time can quickly, taking into account the relevant norms, as well as coordinated water of inhomogeneity and other factors, as a security measure, pressure tank or should store 10min water.

3.2 pump adapter

Pump adapter's main use is when the indoor fire pump fails or in case of fire, indoor fire water shortage for fire engines take water from the fire hydrant, through pump adapter adds water to the indoor fire water supply for fire suppression.

(1) in the sprinkler fire-fighting system, alarm valve group so check valve, pump struggled with in the valve after (along the water flows) water does not flow backwards, because water fire engines arrived at the scene by pump desperately for the indoor fire sprinkler pipe for water, fire, without known to once again start pressure relay and hydraulic alarm alert, do not have to restart again to the fire pump, pump adapter can directly access after the wet alarm valve. [11] But for a system of two or more alarm valve group, also based in the valve after other valve will not be able to the public this pump adapter, so each alarm valve after at least one pump combination. Taking into account the spray regulation law section 10.1.4, "when the automatic sprinkler system is equipped with two and more alarm valve group alarm valve group ago yishe ring water supply piping, for 2 and more alarm valve group system or supposes in valve for good, you can cross to standby. Another pump adapter location should consider the convenience of connecting fire engine pumps and water should not be too far away. (2) of the regulation on article 10.4.2 Jet provides that when the pump adapter supply capacity cannot meet the most negative point role area of flow rate and pressure requirements, measures should be taken to the supercharger. This provision and the doctrine of "7.4.5.2" fire water supply for the vertical division of water supply, water supply in the fire truck pressure range partitions, you should set the pump adapter "compared to increase pump adapter requirements are no longer limited to" one step ", this is the experience and the actual needs, and help to improve system reliability.

(3) the provisions of the regulation of injection pump adapter traffic "to" 10-15L/s, the doctrine of "is" should be "buildings》 is" as is ". This wording should be a cause of: 10-15L/s is normal operation and fire engines long-term play a large range of discharge, and fire system velocity can slightly larger than the water flow rate, combined, according to the regulation of the flow meter nozzle algorithm, for the risk level in no longer limited to 26-30L/s range, but can be, a "should" give designers greater choice and more in line with actual needs. As I recently designed a four-storey building, basement for underground garage, automatic spray with Volume 33L/s, is located 3 or supposes two, I think I'd yishe 2.