EU2 chapter8

HYDROSTATIC PRESSURE

- Defined as force per unit area caused bythefluid’sweight.

HYDROSTATIC PRESSURE

Depends on depth and fluid density, not ontheshapeor size of the container

HYDROSTATIC FORCE

: The weight of thefluidexerts a force on the walls or base of thecontainer.This force acts perpendicular to the surface

Water pressure difference

moves water through the plumbing system

FRICTION LOSS:

occurs as water movesthrough pipes, valves, and fittings

ELEVATION LOSS:

pressure decreases as water is lifted to higher levels

40–80 psi (275–550 kPa)

Normal range:

RESIDUAL WATER PRESSURE-

The pressure at the outlet before a fixture and determines actual water output

PRESSURE DIFFERENCE

- Water will flow from pipes or fixtures only if pressure at the fixture > atmospheric pressure

from high pressure → low- pressure region.

Fluid always moves

Pressure Difference (ΔP)

is the driving force of all fluid flow. Greater ΔP faster or stronger flow

Flow rate
Fluid velocity
Pipe diameter

: higher flow higher friction loss.

: faster flow increases resistance.

: smaller diameter higher frictionloss

Pipe length
Pipe material
Fittings and valves

: longer pipe more friction loss.

: rough pipes create more turbulence

: each adds extra resistance.

FRICTION HEAD:

The equivalent height of a fluid column head required to overcome resistance to fluid flow due to friction within pipes and fittings

PRESSURE DROP CHARTS

- used to estimate friction losses based on pipe type, size, and flow

equivalent length

Each valve or fitting adds resistance to flow. This resistance is expressed as an “______”

EQUIVALENT LENGTH

: Is the length of straight pipe that would cause the same friction loss. A 90°elbow may have the same friction loss as several feet of straight pipe.

Residual Water Pressure

- Is the pressure available at the outlet before thefixture

Higher residual pressure
Lower residual pressure

→greater flow rate→more water consumption

→reduced flowrate

DESIGN LOAD

- The instantaneous peak water demand in a pipe or building expressed in gpm, L/min, or L/s

DESIGN LOAD

Represents the maximum probable flow from multiple fixtures operating together.

FIXTURE UNIT

- Is a numerical value representing the load or demand a plumbing fixture places on a water supply system

Flow rate
Frequency of use

→ how much water the fixture uses when in operation.
→ how often it’s likely to be used during peak demand.

METHOD 1 - SIMPLE EMPIRICAL DESIGN METHOD

- Used for single-family houses or simple structures - No detailed hydraulic analysis needed --- relies on experience and building code requirements - Fixture type determines branch pipe diameter

METHOD 2 - WSFU DESIGN TABLE METHOD

- Can be use for sizing meter and distribution pipes in residential and small commercial buildings based on total WSFU demand and available supply pressure

METHOD 3 - VELOCITY DESIGN METHOD

- Used to size pipes by limiting water velocity to a safe, efficient range for a given design load - Choose the smallest pipe size that does not exceed maximum velocity.