Ch. 5 Hydraulics

Question 1

Study of the factors that influence how the water gets to the fireground.

Answer 1

Hydraulics

Question 2

6 physical facts that apply to water

Answer 2

1) Pressure perpendicular to SURFACE on which it acts
2) Pressure in a confined body of water at rest is the same at all POINTS
3) Pressure of fluid in open container is proportional to its DEPTH
4) Pressure of water in open container is independent of the SHAPE and VOLUME. Depends solely on depth.
5) Pressure of fluid exerts is proportional to DENSITY of fluid
6) Pressure on confined fluid is transmitted EQUALLY throughout that fluid

Question 3

For every foot of height that water rises, it exerts ________. This is known as ______.

Answer 3

.434 psi of force

Head Pressure

Question 4

1 psi pushes a column of water up ______.

Answer 4

2.3 ft

Question 5

Weight of air is equivalent to the pressure exerted by _______ of water or _______.

Answer 5

33. 9 ft

14. 7 psi (1 atm)

Question 6

Most common form of resistance to flow is ______. Only _______ of this loss is due to friction. Remainder is loss due to ________.

Answer 6

Friction loss

A fraction
Turbulence within the stream itself

Question 7

At low flows, there is almost no turbulence, and all of the water molecules move along quite smoothly, which is called ______.

Answer 7

Laminar flow

Question 8

With friction loss, there is a _____ relationship-_______ the length ______ the friction loss.

Answer 8

Direct

Doubling, doubles

Question 9

Supply capabilities include friction loss, ______, _____ and _______.

Answer 9

Capacity of pump
Capacity of water supply source
Capacity of the hose

Question 10

_______ is no indicator of the volume of water available from a hydrant.

Answer 10

Static pressure

misleading and of little use to firefighters

Question 11

Second type of pressure is _________.

Answer 11

Flowing pressure

not residual

Question 12

Low-flowing pressure often indicates the pumper should be placed _________ rather than _________ using an inline hose stretch. This is a good policy for all but the _______________.

Answer 12

Near the hydrant, near the fire

Initial-arriving engine company

Question 13

Minimal residual pressure is _____.

Answer 13

10 psi

Question 14

You must take action to keep the pressure from going below 10 psi. There are two possible actions to take: _______________ or _____________.

Answer 14

Reduce the discharge flow (Not desirable).

Increase the supply with another source (May be impossible or impractical)

Question 15

At a house fire, __________ takes priority over __________.

Answer 15

Speed of water delivery.

The gpm delivered

Question 16

A means for a second pumper to connect to the hydrant and relay the extra available water to the first pumper.

Answer 16

Four-way hydrant valve OR a clappered Siamese

Question 17

Models of Pumpers

500 gpm are ______, 750 and 1,000 gpm are _____ and 1,500 to 2,000 gpm are _______.

Answer 17

Extremely rare (500).
Found far less frequently (750-1,000).
Very common (1,500-2,000)

Question 18

NFPA 1961 recommends a maximum discharge pressure of _______ for LDH.

Answer 18

200 psi

Question 19

One advantage of LDH is _____________.

Answer 19

Rapid deployment and return to service with minimum personnel

Question 20

Most efficient method of water delivery is ________, where the pumper is located _______________.

Answer 20

Positive pumping

On the hydrant

Question 21

When fire exceeds the capability of a handline, a _________ is often brought into play. One of the most common reasons for doing this is that ____________.

Answer 21

Master stream
Fire has extended into the cockloft
water on fire from underneath

Question 22

Advantages of tower ladder basket (2)

Answer 22

Basket on the ground with ability to move

Range of motion of stream

Question 23

Advantages of using flow meter (2)

conjunction with pressure gauge

Answer 23

If kink develops, pump operator can fix.

Hose of unknown length stretched. Knowing type of nozzle to be supplied, simple matter to dial up the proper flow.

Question 24

Ensuring proper volume of water is available

Answer 24

Water supply

Question 25

With splitting flows into two lines, friction loss is only ______ of same flow in a single line. By splitting among three lines, the friction loss is only _______ of the one line loss.

Answer 25

25-35% (2)

10-15% (3)