56
CHAPTER 8
PLUMBING EQUIPMENT AND SYSTEMS
OVERVIEW
It is not an easy task to condense the entire subject on plumbing equipment and systems
into one chapter. Needless to say, we can only cover the bare fundamentals in this single
chapter. Thus, all topics are very brief. If time allows in your class schedule, you may
wish to expand certain aspects of this topic in your class. For example, you may wish to
expand the water supply and storage topic if students are majoring in landscape
architecture, or urban planning; kitchen and bathroom design for architectural and interior
design students; and additional information on equipment and piping layouts for
engineering and construction management students.
One important message to the students should be to increase their interest and therefore
their attention on the importance of plumbing systems in modern society – its impact on
public health and life safety. Without water and proper waste control, no building could
CHAPTER 8
PLUMBING EQUIPMENT AND SYSTEMS
QUESTIONS AND ANSWERS
8.1 National Plumbing Codes usually provide sufficient design data and guidelines
for building sanitary drainage system. Can you explain why this is possible?
8.2 Do National Plumbing Codes provide sufficient data and guidelines to design a
domestic water distribution system? If not, can you explain why this is not
possible?
8.3 What are the equivalents between pound and grains, gallons and cubic feet,
ppm and mg/L?
8.4 Name the five substances (impurities) that must be limited in quality standards
for drinking (potable) water systems.
8.5 Name the major characteristics that govern the quality of water.
8.6 Name the seven processes used to improve the quality of water.
8.7 What mineral content is used to determine the hardness in water?
8.8 Describe the Zeolite water softening process.
8.9 What is osmosis? Reverse osmosis?
8.10 What are the two commonly used water filtration systems?
8.11 A light commercial building is installed with four flush tank type water closets,
two urinals with flushometers, and four lavatories. What is the total water
supply fixture units (wsfu)? What is the probable water demand?
8.12 What are the equivalents of gpm vs. L/s, cfm vs. L/s, psi vs. kPa?
8.13 A building is installed with 300 tons of air conditioning. The air conditioning
unit is water cooled through a cooling tower. How much make-up water
should be provided?
8.14 What is the pressure drop due to friction loss for 400 feet of one-inch PVC pipe
with a flow of 10 gpm?
8.15 What is usually assumed as the equivalent length (EL) of pipe fittings in a
plumbing piping system? (Note: This procedure applies to preliminary design
only.)
During preliminary design (prior to knowing the exact number of the fittings in the
8.16 What is the pressure at the base of a water pipe feeding a plumbing facility 500
feet above the base due to static height alone?
8.17 What is the hot water demand for a residential dishwasher in gpm and total
consumption?
8.18 What type copper pipe is normally used for domestic water system?
8.19 What is the function of a vacuum breaker?
8.20 What is the function of a shock absorber? Where should they be installed?
8.21 What is the most effective method to prevent backflow?
8.22 Based on the pump performance chart shown in Figure 8-19, what pump speed
should be selected for a flow of 10 gpm requiring a total head of 8 feet of water
column (w.c.)? If the same pump is used at a flow of 15 gpm, what total head
can the pump develop?
8.23 Why is a flushometer required for water closets in lieu of flush tanks in public
facilities?
61
8.24 What is the water demand for a pressure tank type water closet per flushing?
For standard gravity tanks?
The water demand per use for a gravity tank type water closet is between 2 and 4
8.25 What is the purpose of a drainage trap? Do water closets require traps?
8.26 What is the nominal rating in drainage fixture units (dfu) of a water closet
with flushometer? with gravity tank?
8.27 What is the difference between waste pipe and soil pipe?
8.28 What is a bathroom group? What is the wfu of a bathroom group with flush
tank? What should be the minimum soil pipe diameter?
A bathroom group is defined as consisting of not more than (1) WC, (1) LV, (1) BT
8.29 A secondary school is planned for 2,000 students, teachers, and staff.
Assuming the population is 50% male and 50% female, determine the
minimum number of plumbing fixtures required. In your judgment is this
adequate?
Based on the general requirements shown in Table 8-7, the number of the minimum
plumbing fixtures recommended for the secondary schools are:
8.30 Calculate the minimum number of plumbing fixtures for a 500 seat movie
theater. Based on your judgment, is this adequate?
8.31 What is a stack? A vent? A stack vent? And a vent stack?
ˍA stack is the vertical portion of the DWV system.
8.32 What is the purpose of a stack vent?
8.33 What are the piping materials commonly used in drainage piping systems?
8.34 What are the joining methods for cast iron pipes? Copper? Plastic?
The normal joining methods for pipes are:
8.35 Normally, municipalities in the U.S. have separate sanitary and storm sewer
systems. There are, however, several major cities that still have combination
storm and sanitary sewer systems. In such case, can the sanitary and storm
piping systems within the building be combined?
8.36 Give the major steps in a sewage primary treatment system, and the secondary
treatment process.
8.37 What is the purpose of a dosing chamber in a septic tank sewage treatment
system? Why?
8.38 What is the maximum number of dfu that can be connected to a 4-inch
horizontal branch?
8.39 What is the maximum number of dfu that can be connected to a 4-inch
building drain with 1/8″ per foot fall? 1/2″ per foot fall?
8.40 A day camp has 150 occupants. Determine the septic tank size. Determine the
linear feet of drain tile required based on 10 minute/inch drop from
(percolation test) and 2-feet wide trenches.
8.41 What is projected roof area?
8.42 What is the rainfall rate of St. Louis, Missouri, based on a storm of 1-hour
duration and a 100-year return period?
8.43 If the roof area is 1500 sq ft, and the roof is adjacent to three vertical walls of
100, 200, and 500 sq ft each. What shall the roof drain or drains be designed
for?
8.44 What is the minimum number of roof drains for any size building? For a
building over 10,000 sq ft of roof area?
8.45 What size horizontal storm drain pipe should be installed for a building having
16,000 sq ft of projected roof area, in a region having 2-inch rainfall rate, and
the drain pipe is laid with 1/16″/ft slope? With 1/4″/ft slope?
8.46 What size roof drain leader should be installed for a 1000 sq ft roof area in a
region with 5″/hour rainfall rate?
66
8.47 In addition to the sanitary facilities, what other water drainage should be
considered in plumbing system design for a large building complex?
8.48 What is the recommended minimum slope of a 4-in. drainline? What is it for a
5-in. drainline?
8.49 What is the equivalent slope in percentage of ¼ in. per foot?
8.50 If the flow rate of an industrial wasteline is 180 GPM, what size drain pipe
shall be used with 2 percent slope?
8.51 What is the maximum number of fixture units (dfu) that may be connected to a
4-in. drainline with ¼ in. per foot slope?
A maximum of 840 dfu may be connected to the line.