Pump MathComment on this page

Metric Pump Math

Flow from a solid stream nozzle

L/min = 0.067 x d² x √NP

d	Diameter of orifice in mm
NP	Nozzle pressure in kPa

Nozzle reaction for solid stream nozzles

NR = 1.57 x d² x NP lbs (force) / diameter (inches) / pressure (PSI)

NR = 0.0015 x d² x NP newtons (force) / diameter (mm) / pressure (kPa)

1 lb = 4.448 newtons

Nozzle reaction for fog stream nozzles

NR = 0.0505 x Q x √NP lbs (force) / flow (GPM) / pressure (PSI)

NR = 0.0156 x Q x √NP newtons (force) / flow (LPM) / pressure (kPa)

Friction loss

FL = C (LPM/100)² (meters/100)

FL = C x Q² x L

FL	Friction loss in kPa
C	Friction loss co-efficient
Q	Flow in 100s of LPM (LPM/100)
L	Hose length in 100s of meters (length/100)

For a wyed hoseline, calculate Q as

(LPM line A + LPM line B) / 100

Appliance friction loss

Insignificant when flowing through appliances < 1,400 LPM

• 70 kPa for each appliance other than master streams
• 175 kPa for all master stream appliances

Elevation pressure

10 kPa per meter
40 kPa per story

EP = 10 x H

H	Height in meters

EP = 40 (stories - 1)

Siamesed hoselines

When 2 hoselines of equal length are siamesed to supply a fire stream, friction loss is approximately 25% of a single hoseline at the same nozzle pressure.

When 3 hoselines of equal length are siamesed to supply a fire stream, friction loss is approximately 10% of a single hoseline at the same pressure.

Pump Discharge Pressure (PDP)

PDP = NP + TPL

NP	Nozzle pressure
TPL	Total pressure loss (FL attack + FL supply + APP loss)

Net pump discharge pressure (NPDP)

NPDP = PDP - supply/intake pressure

Dynamic pump intake calculation

Compound % drop	Additional supply available
0-10%	3x current flow
11-15%	2x current flow
16-25%	Same as current flow
> 25%	More water available buy less than current flow

Shuttle operations

UT + TTF + FT + RT = TRT

UT	Unload/dump time
TTF	Time to travel (to fill site)
FT	Fill time
RT	Return time
TRT	Total run time