8/19/2019 6 Pdfsam Att-4 BLRT-FD-CAL-SA-3308 R1 Firewater System Sizing Calculation

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Engineering and Design forLNG Receiving Terminal Project Bojonegara

BLRT-FD-CAL-SA-3308Firewater System Sizing Calculation

Page 6 of 10 Tokyo Gas Engineering Co., Ltd. 

4. Calculation

4.1 Firewater Demand

Firewater demand calculation has been performed for 13 fire zones and trestle.

Detailed theoretical firewater demand for these fire zones is given in Table 3.

4.2 Firewater Pumps

The TERMINAL will be equipped with its own firewater pumps. The pump size

will be based on the total firewater demand on the largest fire event in a single

zone since “double jeopardy” is not considered. There will be 2x100% electric

motor and diesel engine driven firewater pumps. The required capacities of the

pumps for main areas are as follows:

 Area Flow rate (m3

Unloading jetty

/h)

943

LNG tank 301

Process area 659

 According the calculation, firewater pumps with capacity of 1170 m3/h at 13

kg/cm2

4.3 Firewater Line Sizing

G will be able to meet the firewater requirement for each of main area. The

pressure shall be further verified after the water curtain nozzles are selected.

The ring main is designed in such a way that any damage or maintenance of one

section will not interrupt the fire water supply to the users installed on the other part

of the ring main.

The firewater line sizing and pressure drop calculation is done using the following

equation:

 Average liquid velocity in pipe,

v =353.6 Q/d2 

Where v= flow velocity (m/s)

Q = flowrate (m3

The maximum line velocity used is 4.6 m/s in most cases according to Section

4.14.3 of NFPA 20, using 150% of the rated flow of 1170 m

/h)

d = internal pipe diameter (mm)

3/h as the maximum flow