Month 12; Hydraulics Chapter 8 Book Formulas

Question 0

What is total pressure loss?

Answer 0

Friction Loss and Elevation Pressure.

Question 1

Driver Operator Handbook
Chapter 8
Theoretical Pressure Calculations

Answer 1

.

Question 2

Equation A

Friction Loss

Answer 2

FL = C x Q^2 x L

FL = Friction loss in psi
C = Friction loss coefficient
Q = Flow rate in hundreds of gpm (flow/100)
L = Hose length in hundreds of feet (length/100)

Question 3

Friction Loss Coefficients

• 1”Booster
• 1 3/4” Hose with 1 1/2” couplings
• 2 1/2”
• 5”

Answer 3

-1” Booster = 150

1 3/4” Hose with 1 1/2” Couplings = 15.5

• 2 1/2” = 2
• 5” = .08

Question 4

Equation B

Elevation Pressure (Feet)

Answer 4

EP = 0.5H

EP = Elevation Pressure
0.5 = Constant
H = Height in Feet

Question 5

Equation C

Elevation Pressure (Stories)

Answer 5

EP = 5psi x (# of stories -1)

EP = Engine Pressure
5psi = constant

Question 6

Equation D

Pump Discharge Pressure

Answer 6

PDP = NP + TPL

PDP = Pump discharge pressure in psi
NP = Nozzle pressure in psi
TPL = Total pressure loss in psi (appliance, friction, and elevation losses)

Question 7

Equation E

Net Pump Discharge Pressure

Answer 7

NPDP (pps) = PDP - Intake Reading

NPDP (pps) = Net pump discharge pressure from a positive pressure source.

PDP = Pump discharge pressure

Question 8

What is elevation pressure?

Answer 8

Occurs anytime there is a change in elevation between the nozzle and the pump.

Question 9

What is friction loss + causes?

Answer 9

Pressure loss due to friction.

-Causes = hose condition, coupling condition, kinks. Biggest cause is volume of water flowing per minute (GPM).

Question 10

What is total pressure loss?

Answer 10

friction loss and elevation pressure

Question 11

Appliance friction loss is insignificant in cases where the total flow through the appliance is less than how many gpm?

Answer 11

Less than 350 gpm

Question 12

When flowing over 350 gpm what psi loss is there for each appliance (other than a master stream appliance?)

What is the PSI loss for a master stream appliance?

Answer 12

-Other appliances = 10psi per appliance

Master Stream Appliance = 25 psi, regardless of the flow

Question 13

Water exerts a pressure of what per foot of elevation?

Answer 13

.434psi

When a nozzle is operating at an elevation higher than the apparatus, this pressure is exerted back against the pump. To compensate for this pressure “loss”, elevation pressure must be ADDED to friction loss to determine total pressure loss.

Operating a nozzle lower than the pump results in pressure pushing against the nozzle. This “gain” in pressure is compensated for by subtracting the elevation pressure from the total friction loss.

Question 14

GPM Formula

Answer 14

GPM = 29.7 (D^2) (square root of nozzle pressure)