Chapter 6 - Theoretical Pressure Calculations

A key rule a D/O should remember when determining friction loss is that doubling the flow, ___ the friction loss

Quadruples

What is the first step for determining friction loss?

Obtain the FL coefficient for hose being used

The largest factor relating to avoidable friction loss is the:

Volume of water flowing per minute

What is the friction loss that the manual establishes for all master stream appliances, regardless of the flow?

25 psi (175 kPa)

What is the friction loss that the manual establishes for each appliance (other than master stream) in a hose assembly flowing at 350 gpm (1400 L/min) or greater)?

10 psi (70 kPa)

To determine friction loss in a multistory building, what is the set constant number that is multiplied by the number of stories minus one?

5 psi (35 kPa)

Total pressure loss (TPL) includes appliance pressure loss when flow exceeds:

350 gpm (1400 L/min)

Generally, what type of hose layout refers to a hose with a single or multiple hose layouts with equal diameter and length components?

Simple

Two hoselines of equal length that are siamesed to supply a fire stream or another pumper have a lower friction loss when compared to a single hoseline of approximately:

25%

When pumping multiple hoselines from separate discharges, the hose with the ___ represents the pump discharge pressure at the individual pump

Highest friction loss

When pumping to a manifold that has multiple hoselines of unequal lengths and/or the diameter is different, the TPL in the system is based on the:

Highest pressure required in any of the hoselines

When determining pump discharge pressure, what nozzle pressure should a D/O compensate for a solid stream nozzle (handline)?

50 psi (350 kPa)

When determining PDP, what nozzle pressure should a D/O compensate for a solid stream nozzle (master stream)?

80 psi (560 kPa)

When determining PDP, what nozzle pressure should a D/O compensate for a fog nozzle?

100 psi (700 kPa)

When calculating net PDP while drafting from a static source, the D/O must include both the elevation loss for lift and:

Friction loss in the hard sleeve intake hose

If 300 gpm (1135.62 L/min) is flowing from a nozzle, what is the total pressure loss due to friction for 400 ft (120 m) of 2.5 in (65 mm) hose?

FL = CQ²L

72 psi (547.78 kPa)

What is the TPL due to friction in 600 ft (180 m) of 4 in (100mm) hose when 750 gpm (3000 L/min) is flowing?

FL = CQ²L

67.5 psi (494.1 kPa)

What is the TPL due to friction in 250 ft (75 m) of 1.75 in (45mm) hose when 150 gpm (500 L/min) is flowing?

FL = CQ²L

87.19 psi (644.2kPa)

Calculate the TPL due to elevation for a hoseline operating at the top of a 100 ft (30 m) hill where EP = 0.5H (10H).

50 psi (300 kPa)

What is the TPL due to elevation of a hoseline that is operating on the ninth floor of a building?

EP = 35 kPa x (# stories - 1)

40 psi (280 kPa)

A pumper must supply 500 ft (150 m) of 2.5 in (65 mm) hose that is flowing 300 gpm (1200 L/min) through a fog nozzle. Determine the PDP required to adequately supply the hoseline.

PDP = NP + TPL

= 190 psi (1384.72 kPa)

What is the NPDP of a pumper being supplied from a hydrant with 20 psi (150 kPa) on the intake gauge and is discharging water at 170 psi (1700 kPa)?

150 psi (1550 kPa)