Sprinkler Cal Info Hong Kong

AppendixII - Fire Services System

Fire Services System

1. Fire Services Control Center

From the regulation by F.S.D., the F/S Control Center which has minimum one hour fire resisting period located at ground floor on the main face of a building, preferably adjacent to main entrance. In addition, the room should be large enough to settles all the house equipment, recorders and annunciators.

The recommended room size is 3m(L) x 3m(W)

2 Automatic Sprinkler System

2.1 Automatic Sprinkler Tank Size

In the design, reliable source is employed that the water tank size is dependent on inflow.According to BS5036, Part 2, for ordinary Group III, the minimum design capacity of tank is 75m3 and the maximum period of inflow for section tank is 60 min.

\ The Internal tank size is 5m(L) x 5m(W) X 3M(H)

2.2 Pump Rating

2.2.1 Duty Pump

To calculate the duty pump rating, friction loss of the pipes and fittings should be investigated first. According to the above pressure and flow requirement, the pump head required for each installation is calculated based on the equation shown in BS 5306,

(a) Static Pressure Difference

Static pressure difference (pd) = 0.1h

h = the vertical distance between the points (m)

(b) Pipe and Fitting Friction Loss

Pipe and fitting friction loss (PL ) = k x L X Q1.85

k = a constant for the size, type and condition of the pipe For 100 mm G.I. pipe, k = 1.35 x 10-8 (BS 5306)

L = Equivalent length of pipes and fittings (m)can be found from the table below

Q = Flow rate through pipe (l/min)

Equivalent length of the fitting

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AppendixII - Fire Services System Fitting Average

equivalent length (m)

90° screwed elbow 1.89Standard screwed tee (150mm)

8.61

Gate valve 0.81Alarm 5.07

Also, by BS5306:Part 2:1990, Section 4, 17.4.6.3, for ordinary group III Hazard (OH III), if the distance between the highest and lowest sprinklers is less than 15m, the following pump requirement should be follow:

Nominal Rating High Flow Low FlowPressure at

pump outlet

Flow Pressure at ‘C’ gauge


Flow

1.4 bar 2250 L/min

2.9 bar 1350 L/min

3.2 bar 1100 L/min

If the distance between the highest and lowest sprinklers is between 30m and 45m, the following pump requirement should be follow:

Pressure at pump outlet



Flow

2.5 bar 3100 L/min

5.9 bar 1350 L/min

6.2 bar 1100 L/min

Assumption: All distribution pipes are made of Galvanized heavy Steel.

With regard to the building geometry, there are totally 5 pumps. One the public area at LG/F and G/F while the others for the voids in the residential block ( 2 for Block 1 & 2 for Block 2). Base on the following information, the duty pump rating can be determined.

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AppendixII - Fire Services System (a) Duty Pump for LG/F and G/F

According to the building geometry, the horizontal pipe run from the F/S pump room to the farthest shop 4 is 50m while the vertical pipe run from the pump at LG1 to the ceiling level of G/F is 6.5m. Also, the actual pump rating is accessed by adding the nominal rating to a 10% safety factor. Hence, the result is shown as follow.

G/F

Public Services 3.5m (Floor-to-floor height)

OH III LG1

Control valves 3m

Nominal flow

L = 50m pipe run + 4 bends + 2 gate valve + 1 tee + 1 alarm = 50 + 4(1.89) + 2(0.81) + 8.61 + 5.07

= 72.9 mPL = 1.35 x 10-8 x 72.9 x (2250)1.85

= 1.57 barPd = 0.1 x 6.5

= 0.65 bar\ The nominal flow requirement = 1.4 + 1.57 + 0.65

= 3.62 bar/2250L=36.2 mH/2250L \ The actual flow requirement = 40mH/2250L

High flow


= 72.9 mPL = 1.35 x 10-8 x 72.9 x (2250)1.85

= 1.57 barPd = 0.1 x 6.5


= 5.12bar/1350L = 51.2mH/1350L \ The actual flow requirement = 56mH/1350L

Low flow


= 72.9 mPL = 1.35 x 10-8 x 72.9 x (2250)1.85

= 1.57 barPd = 0.1 x 6.5


= 5.42bar/2250L = 54.2mH/1100L \ The actual flow requirement = 60mH/1100L

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AppendixII - Fire Services System (b) Duty Pump for zone 1 of block 1

Since the maximum height of a zone is 45m, the maximum reached floor is 14. Therefore, The served floors for zone 1 are ranged from 1/F to 14/F. Also, the same as before, the actual pump rating is accessed by adding the nominal rating to a 10% safety factor. Hence, the result is shown as follow.

14/F

40m

OH III G/F

Control valves 3m

Nominal flow


= 94.8 mPL = 1.35 x 10-8 x 94.8 x (3100)1.85

= 3.68 barPd = 0.1 x 40

= 4 bar\ The nominal flow requirement = 2.5 + 3.68 + 4

= 10.2 bar/3100L=102 mH/3100L \ The actual flow requirement = 115mH/3100L

High flow


= 94.8 mPL = 1.35 x 10-8 x 94.8 x (3100)1.85

= 3.68 barPd = 0.1 x 40



Low flow


= 94.8 mPL = 1.35 x 10-8 x 94.8 x (3100)1.85

= 3.68 barPd = 0.1 x 40



(c) Duty Pump for zone 2 of block 1

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28/F

40m

OH III 15G/F

Control valves 43m

Nominal flow


= 135mPL = 1.35 x 10-8 x 135 x (3100)1.85

= 5.24 barPd = 0.1 x 80



High flow


= 135mPL = 1.35 x 10-8 x 135 x (3100)1.85

= 5.24 barPd = 0.1 x 80



Low flow


= 135mPL = 1.35 x 10-8 x 135 x (3100)1.85

= 5.24 barPd = 0.1 x 80



(d) Duty Pump for zone 1 of block 2

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AppendixII - Fire Services System 10/F

28m

OH III G/F

Control valves 3m

Nominal flow


= 52.8 mPL = 1.35 x 10-8 x 52.8 x (3100)1.85

= 2.05 barPd = 0.1 x 28


= 7.35 bar/3100L=73.5mH/3100L \ The actual flow requirement = 81mH/3100L

High flow


= 52.8 mPL = 1.35 x 10-8 x 52.8 x (3100)1.85

= 2.05 barPd = 0.1 x 28



Low flow


= 52.8 mPL = 1.35 x 10-8 x 52.8 x (3100)1.85

= 2.05 barPd = 0.1 x 28



(e) Duty Pump for zone 2 of block 2

18F

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20m

OH III 11F

Control valves 34m

Nominal flow


= 109mPL = 1.35 x 10-8 x 109 x (3100)1.85

= 4.23 barPd = 0.1 x 54

= 5.4bar\ The nominal flow requirement = 2.5 + 4.23 + 5.4


High flow


= 109mPL = 1.35 x 10-8 x 109 x (3100)1.85

= 4.23 barPd = 0.1 x 54



Low flow


= 109mPL = 1.35 x 10-8 x 109 x (3100)1.85

= 4.23 barPd = 0.1 x 54



From the above calculation, the duty pump ratings can be found. In addition, the duty curves are summarized as below:

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AppendixII - Fire Services System 725 1100 1350 1750 2350 2700 3100

Pump for LG, G/F 62 60 56 44 38Zone 1(Block 1) 155 153 150 141 131 123 115Zone 2(Block 1) 217 215 211 200 190 181 173Zone 1(Block 2) 123 122 118 105 97 88 81Zone 2(Block 2) 180 174 171 165 153 145 133

Duty Pump Chart

0

50

100

150

200

250

725 1100 1350 1750 2350 2700 3100

Flow rate

Hea

d (m

)

Pump for LG, G/F

Zone 1(Block 1)

Zone 2(Block 1)

Zone 1(Block 2)

Zone 2(Block 2)

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2.2.2 Jockey Pump

From BS5306, Part 2, each installation rise pipe shall be with a jockey pump to maintain the static pressure at any check or alarm valve at not less than 1.25 times the static head difference between the valve and the highest installation.

\ Jockey pump head = Static head x 1.25 x 1.1 (safety margin)

In addition, the minimum design density for OHIII = 5 mm/min the minimum conceal for OHIII area = 60 l/min

= 1 l/s

\ According to the following regulation, the rating of jockey pumps can be found as follow:

Pump Rating Jockey pump for LG/F & G/F 8.1 mH/1 l/s Jockey pump for zone 1 (Block 1) 60 mH/1 l/sJockey pump for zone 2 (Block 2) 115 mH/1 l/sJockey pump for zone 1 (Block 2) 43 mH/1 l/s Jockey pump for zone 2 (Block 2) 74.5mH/1 l/s

2.3 Pressure for starting the jockey, duty and standby pumps

As mentioned before, the duty pump, jockey pump and standby pump will operate automatically when the pressure drop below 95%, 90% and 80% of the designated pressure, Their starting pressures are as follow:

Pumps for Public Services at LG/F & /GF

Type of Pump Starting pressureDuty pump 8.1mH x 0.95 = 7.7 mH

Jockey pump 8.1mH x 0.9 = 7.3 mHStandby pump 8.1mH x 0.8 = 6.5 mH

Pumps for zone 1 (Block 1)

Type of Pump Starting pressureDuty pump 60mH x 0.95 = 57 mH

Jockey pump 60mH x 0.9 = 54 mHStandby pump 60mH x 0.8 = 48 mH

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AppendixII - Fire Services System Pumps for zone 1 (Block 2)



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2.4 Pipe Sizing

2.4.1 Sprinkler Tank incoming pipe

The incoming water requirement (y):

y = {(max. pump flow rate)x 60 min - V in litres } / max. period of inflow for suction tank= {2250 l/min x 60 - 75 (1000 ) }/ 60x60= 17 l/s

For the flow rate of incoming water pipe = 17 l/s, according to CIBS 4, 100mm galvanized pipes are usedPipe velocity = 1.8 m/s, pressure loss per unit length = 350 Pa/m

2.4.2 Sprinkler Duty Pump Suction Pipe

Since the depth of water stored in the sprinkler tank is greater than 2m, the pump set is regarded as being under suction lift From table 30 of BS5306, the suction pipe size is 200mm diameter for Ordinary Hazard Group III.

2.4.3 Sprinkler Duty Pump Discharge Pipe

Since the discharge pipe is then connected to the sprinkler control valve and the riser, the minimum size should be the same as the riser(100mm). Therefore, the size of discharge pipe is 100mm diameter.

2.4.4 Sprinkler Jockey Pump Suction and Discharge Pipe

Due to the function of the pump, only very little water will be passed and the hence flow rate is very small (1 l/s), 50mm diameter pipes are chosen.

2.4.5 Sprinkler Upfeed Pipe & Distribution Pipe

From BS5306 Part 2, the distribution pipes(include all risers and drops), between the highest design point in the installation and the sprinkler installation main control valve set(in low-rise installation), shall be sized by hydraulic calculation based on the values of table 59. The maximum friction loss shall not exceed 0.5 bar at a flow rate of 1000 l/min.

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G

Water Main

Pumps

Water Tank

Effective Volume = 75m3

The internal tank size =10200(L) x 6050(W) x 1620(H)mm

y l/s

2250 l/min (From Table 28 of BS5306)

AppendixII - Fire Services System In the proposed building, since heavy grade G.I. pipe is used, the pressure loss should based on the following equations:

Static pressure difference (pd) = 0.1hPipe and fitting friction loss (PL ) = k x L X Q1.85

As mentioned before, the horizontal pipe run from the F/S pump room to the farthest shop 4 is 50m.\the pressure losses are:

(a) 80mm diameter pipe

PL = 4.97 x 10-8 x 72.9 x (1000)1.85 = 1.29 bar >0.5 bar

\ 100mm heavy grade G.I. pipe is used for the upeed and horizontal distribution pipe.

3. Fire Hydrant / Hose Reel System

3.1 Sump Tank, Sump Tank Pump and Riser Sizing

Generally, the transfer tank should hold at least 5 minutes pump’s flow rate. Normal range of holding time is between 5 to 20 minutes, higher the holding time will be better as the pump will not run all day. i.e. allow 20 mins pump’s flow rate the capacity.

\ The effective capacity = 20 mins x 60s/min x 1.67 l/s ~ 2500 litres

Since the sump tank is used to store the water of two roof tanks( Block 1 and Block 2), the actual tank size should be double.

The effective capacity of the tank is 5000LThe internal tank size is 2m(L) x 2m(W) x 1.5m(H)

In addition, based on the recommendation of FSD, the 27m3 supply tank for F.H /H.R is to be filled within 6 hours.

\ Flow rate of the pump = (27m3 x 1000 litre/m3) / 6 hr x 3600 s/hr= 1.25 l/s

· Assume an internal diameter 100mm galvanised steel pipe is used as the rising main because it is the commercial size for a building over than 45m height.

Then water flow velocity = 1.3m/s Pressure loss per unit length = 400 Pa /m run

Equivalent length of pipe = 1.7 m Static head = 140m

Pipe friction loss = 1.35 x 10-8 x (1.67 x 60)1.85 x 140= 0.0095 ~ 0 ( \ can be neglected )

Then, the pump head = 140m + 140x 0.04 = 145.6mH

~ 160mH (10% safety margin)

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(b) 100mm diameter pipe

PL = 1.35 x 10-8 x 72.9 x (1000)1.85 = 0.35 bar < 0.5bar


The rating of pumps 1.67 l/s , 160mH are selected.Diameter of risers = 100mm

3.2 Supply(Roof) tank and Roof Pump sizing

According to Code of Practice of Minimum Fire Services Installations and Equipment, the minimum quantity of water required to be available which is regarded to the floor area factors of the largest floor. As the gross floor area in the proposed building is “Over 460m 2 but not exceeding 920m2”. Therefore, a 27000L (27m3) roof tank should be installed in both buildings.

The effective volume of the tank is 27000LThe Internal tank size is 3.5m(L) x 3.5m(W) x 2.5M(H)

· Assume an internal diameter 100mm galvanised steel pipe is used as the main distribution pipe. Then water flow velocity = 1.3m/sPressure loss per unit length= 400 Pa /m runEquivalent length of pipe = 1.7 m

By the relation that Pressure(P) is proportional to the square flow rate (Q),i.e. P a Q2, Pressure at 28/F is 3.5 + 1.5 bar = 5 bar,

Flow rate at 27/F is 450 l/min = 7.5 L/s\ k = 8900

Also, Pressure at 27/F is 3.5 + 1.5 + 3 - 3x 0.04 = 7.88 bar \ Flow rate = 9.4 L/s

With reference to COP, it states that the fire pumps shall be capable to provide adequate flow for any 2 hydrant outlets ( i.e. each with a flow of 450 L/min at a running pressure of not less than 350kPa ) operating simultaneously with an aggregate flow of not less than 900 L/min.

\ The flow rate of the pump = 7.5 + 9.4 = 20L/s = 1020L/min

For the approximate length of horizontal running at roof = 5m,the static head from the pump to the fire hydrant outlet = 5m and assume there is no fitting loss

Then, the pump head = 50-5+(5+5) x 0.04~ 60mH (10% safety margin)

The rating for both Roof Pump are 1020 l//min with 60 mH.

3.3 Intermediate booster pump

The rating of the pump is the flow rate of any two hydrant outlets each with a flow of 450l/min at a running pressure of not more than 850kPa.

\ Rating of Pump = 7.5 x 2 = 15 L/s

= 900 L/S The Pressure head = 28 x 3 + 28 x 3 x 0.02 = 100 mH.

= 110mH (10% safety margin)The rating Intermediate booster pump is 900L/min with 110 mH.

3.4 Hose reel branch pipe From clause(i)(b) of 5.14 of the FSD circular letter no. 8/90, rising mains and associated pipework used for the hose reels shall be not less than 40mm nominal bore and pipes feeding individual hose reel shall not be less than 25mm nominal bore.

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\ All hose reel pipes shall be Æ40mm except the pipes feed to individual hose reel shall be Æ25mm

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Sprinkler Cal Info Hong Kong