Thursday, April 19, 2012


 Plumbing Systems

Plumbing is a system of piping, apparatus, and fixtures for water distribution and waste disposal within a building. This chapter covers the basic water supply and water distribution systems, the theater of operations (TO) water supply and water distribution systems, and the sewerage system. Plumbing also includes the installation and maintenance of these systems. When architects design a building, they prepare a set of prints and a set of specification sheets detailing the types and quality of materials to be used. Plumbers use the prints and specifications to layout and plan the project.

Basic Water Supply And Water Distribution Systems

1-1. A water supply system receives, treats, and moves water to a water distribution system. Water may come from a stream or lake, a deep or shallow well, or a reservoir which collects surface water. The water supply system purifies and pumps the water into a storage tank. After the water is purified, it is released into the distribution system. The distribution system is an arrangement of connected pipes (called a run) that carries the water to its destination. This system usually has a means of heating some of this water.


1-2. See Appendix B for information on construction plans, prints, drawings, and plumbing and heating symbols.


1-3. A plumber should be able to install a complete water supply system by using a plan together with standard and special detail drawings and a BOM. A standard detail drawing will show the water heater and standard storage tank connections. The plan will show the type of piping by size and fittings (see Appendix B).


1-4. For more information on utility- and building-waste system plans, see Appendix B.


1-5. Prints are used for structures and equipment in water supply and water distribution systems. The type of print depends on whether the unit is constructed or if it is a package unit to be assembled in the field (see Appendix B, paragraph B-8).


1-6. The designer (architect) or draftsman usually prepares a BOM (DA Form 2702) when preparing the original drawings. However, if no BOM accompanies the field prints, the plumber must compile it. Appendix C gives instructions for preparing a BOM.


1-7. The main water supply system provides potable cold water at the main at a pressure that meets National Plumbing Code standards. The water service main for the plumbing installation Ts into the main water supply. The plumbing system must provide enough water for normal use at each outlet.
1-8. Fixture supply risers take water from the main supply to the fixtures on each floor level. Each fixture supply riser must have a diameter large enough to supply water to all the fixtures it connects. The size is determined by the design load for the riser (refer to Appendix D, Tables D-3 or D-4).


1-9. Cold-water systems may use galvanized-iron or galvanized-steel pipe, copper tubing, plastic pipe, brass, cast iron, galvanized, wrought iron, or other approved material. The material used depends on the—
• Amount of water to be supplied.
• Water pressure.
• Corrosion factor for different types of pipe in different temperatures.
• Cost.
• Availability.


1-10. The size of water supply piping depends on the—
• Water pressure and friction loss through the length of the pipe.
• Number and kinds of fixtures installed (fixture demand).
• Number of fixtures in use at a given time (factor of simultaneous use).
• Type of flushing devices (refer to Chapter 4).

Friction Loss

1-11. When a liquid flows through a pipe, layers move at different speeds, with the center layer moving fastest. This resistance to flow (called friction loss) varies with different types of pipe. Pipe friction, in turn, causes a drop in water pressure. In a small pipe, this friction loss is overcome by increasing the water pressure. If higher water pressure is not possible, increasing the pipe size can reduce friction loss. See Appendix D for friction loss in different types of pipe.

Water Hammer

1-12. In a water supply system, water hammer occurs when flowing water is stopped abruptly or cannot be compressed, causing the flowing water to slam against the valve with the same amount of pressure as applied to the water system (such as when you flush a water closet, the water closet's tank completes the filling action, and the control valve in the tank closes).
1-13. The effects of water hammer are noise from rattling pipes and sometimes leaky pipe joints, both of which can be eliminated easily by installing a device called a expansion chamber to slow the water in the plumbing system. The expansion chamber shown in Figure 1-1 is capped at the upper end causing it to fill with air, not water. Air, unlike water, can be compressed. Therefore, when the water flow is stopped abruptly, the air in the air chamber works like an automotive shock absorber relieving the slamming action against the valve. Install expansion chambers in the water supply system on both hot and cold service lines at each major fixture within a structure.
1-14. Expansion chambers can be purchased or fabricated. Figure 1-1 shows an example of a constructed expansion chamber. The type of pipe and the dimensions used are not critical, but ensure that the section identified as the riser is at least 6 inches long.
Expansion Chamber Construction
Figure 1-1. Expansion Chamber Construction

Water Pressure

1-15. Pressure in the main usually ranges from 45 to 60 pounds per square inch (psi). If the pressure is over 60 psi, a pressure-reducing valve must be placed in the water service line at its entry to the building. The size of the water service pipeline, the rate of use, the length of the line, and the outlet height in the system control the pressure available at the outlet. If the water pressure is less than 15 psi, use a tank and a pump or other means to provide pressure. If the water pressure is over 80 psi, use an approved pressure regulator.

Calculations for Sizing Pipe

1-16. The minimum practical size for a water service line is 3/4 inch. This size should be used even when calculations indicate a smaller one. Calculations for factoring loss of pressure in complex systems are beyond the range of this manual. For simple systems, use approximate figures to find the pipe size. Tables D-1 and D-2, Appendix D, give capacities and psi for galvanized-steel/iron pipe, copper tubing, and plastic pipe. Use these tables combined with the maximum fixture demand and simultaneous use factor to determine pipe sizes.
1-17. Maximum Fixture Demand. The maximum fixture demand in gallons per minute (GPM) is the total amount of water needed to supply all the fixtures at the same time. Estimate the maximum fixture demand by counting the number and types of fixtures in the plumbing system. Table 1-1 gives the maximum fixture demand for different fixtures.
Fixture Demand (in GPM)
1-18. For example, what is the maximum fixture demand for a plumbing system which consists of the following 14 fixtures: 2 water closets, 4 lavatories, 2 showers, 3 urinals, 1 slop sink, 1 laundry tub, and 1 floor drain?
Use Table 1-1 and the following steps:
Step 1. Multiply the number of each fixture by the GPM of that type fixture (from Table 1-1).
Step 2. Total these figures.
1-19. The result is a maximum fixture demand of 313.5 GPM.
NOTE: Use the fixture demand (313.5 GPM) with the simultaneous use factor to select the pipe size.
1-20. Simultaneous-Use Factor. The simultaneous-use factor is the percentage of fixtures potentially in use at a given time (Table 1-2). It is an estimate of the total demand on a water supply system, expressed as water supply fixture units. Simultaneous-use factors decrease as the number of fixtures in a building increases. Use the formulas in Table 1-2 to determine simultaneous use factor.
Simultaneous-Use Factor
1-21. If a table for the simultaneous-use factor is not available, estimate the probable demand by computing 30 percent of the maximum fixture demand in gallons.
1-22. Continuing the example in paragraph 1-18, the 14 fixtures would have a simultaneous use of 42.72 percent (round up to 43 percent). Since the fixture demand was 313.5 GPM, the water service line must have a capacity of 43 percent of 313.5 (110 GPM). What size of pipe would be needed for a 60-foot long pipeline with a pressure at the main of 45 psi (refer to Appendix D, Tables D-1 and D-2)?
Step 1. Read down the 60-foot column in Tables D-1 or D-2, to 1 1/2 inch diameter.
Step 2. Read across (left) to the psi column and establish the given as 45 psi.
Step 3. Read back to the 60-foot column. TableD-1 shows 150GPM(the quantity that includes 110 GPM);
Table D-2 shows 155 GPM(round up to 160 GPM).
1-23. Either 1 1/2-inch galvanized, copper, or plastic piping would be large enough for the water service line.
NOTE: Remember, the minimum practical size for a water service line is 3/4 inch. This size should be used even when calculations indicate a smaller size.


Main Water Supply Line

1-24. The main water supply is a pipe, usually hung from a ceiling, with branches connected to serve the fixture risers. This supply pipe has the same diameter as the water service from the main and is centrally located to  provide short takeoffs to the fixture supply risers throughout the building. To reduce friction loss, lay the main supply piping as straight as possible. The main supply pipe must not sag or trap water. It should be graded slightly, up to 1/4 inch per foot, dropping toward the water meter. At the low end of the
grade, place a drip cock or stop-and-waste valve for draining the pipe in the winter. A drainpipe may be needed to carry the wastewater from the opening in the valve to a floor drain or sump. If it is impossible to grade all the piping to one point, all parts that cannot be centrally drained should have separate drip cocks or stop-and-waste valves. The main supply pipe must be well supported to take its weight off the fittings and to prevent leaks.

Fixture Supply Risers

1-25. Use reducing Ts to connect fixture supply risers to the main supply. Run the risers through the interior walls of the building. Tighten all the joints before the partitions are finished. Use pipe rests or clamps to support vertical fixture supply risers at each floor level. (Fixture supply risers must not depend on the horizontal branches for support.) Horizontal-fixture branches should be well supported and graded upward toward the vertical-fixture supply risers.


1-26. Install gate valves in each vertical supply riser, so that a section can be repaired without shutting off the water to other sections. Small gate valves on the supply to each fixture allows for shutting off the water for faucet repairs.


1-27. Inspecting for leaks is important. A leaky joint wastes water and causes costly damage to the building. In new construction, test the entire system for leaks before the floor and partitions are closed up. When performing this test, use the water pressure from the main that feeds the system. While the system is under pressure, inspect each joint for moisture. If a leak is detected in a joint, tighten the joint or replace it by cutting the pipe and connecting a new section with a union. When working with copper soldered joints or plastic solvent-cement joints, drain the pipe and then connect the joint. Copper compression joints can be tightened or replaced.


1-28. After installation or repair, clean and disinfect plumbing pipes and other parts of a water supply system carrying drinking water before use. Flush the system to remove dirt, waste, and surface water. Disinfect each unit with a chemical such as a solution of hypochlorite or chlorine.


1-29. Under average conditions, use the dosages (in parts per million [ppm]) in Table 1-3. The chlorine dosage required to disinfect a unit depends on the—
• Contact time.
• Amount of organic chlorine-consuming material present.
Chlorine DosageVolume of Water Disinfected (By Pipe Size)
• Volume of water to be disinfected. Table 1-4 gives the volume of water for different sizes and lengths of pipe.


1-30. Use portable gas chlorinators to apply the liquid chlorine. Chlorine cylinders should not be connected directly to the mains because water may enter the cylinder and cause severe corrosion, resulting in dangerous leakage.
A solution of hypochlorite is usually applied by measuring pumps, gravity feed mechanisms, or portable pipe-disinfecting units. Use the following steps to apply disinfectant:
Step 1. Flush all sections thoroughly at a velocity of at least 3 feet per second (fps) until all the dirt and mud are removed.
Step 2. Plug all branches and other openings with plugs or heads properly braced to prevent blowouts.
Step 3. Insert the disinfectant into the mains through taps or hydrants at the ends of each section.
Step 4. Bleed out any air trapped in the line.
Step 5. Add the predetermined chlorine dosage as the main slowly fills with water.
Step 6. Continue feeding until the water coming from the supply end contains the desired amount of chlorine.
Step 7. Keep the chlorinated water in the unit for 24 to 48 hours.
Step 8. Flush the main until the water contains only the amount of chlorine normally in the supply.
Step 9. Analyze samples daily for bacteria until the analyses show no further need for disinfection. If the samples are unsatisfactory, rechlorinate.



1-31. Galvanic corrosion (resulting from a direct current of electricity) occurs in a plumbing system that includes two different kinds of metal pipe, such as galvanized pipe and copper pipe. See Chapter 3 for reducing and repairing corrosion.


1-32. Hard water contains a large amount of calcium and magnesium compounds, which prevent soap from lathering. This forms a scum that slows the flow of water. The scum deposits harden and form scale. See Chapter 3 for reducing and removing scale.

Frozen Pipes

1-33. Water supply lines may freeze when exposed to temperatures below 32 degrees Fahrenheit. Outside pipes must be buried below the frost line. In northern zones, this is 4 feet or more. If the building temperature falls below freezing, inside pipes may also freeze, causing the pipe to break at the weakest point. Use the procedures in Chapter 3 to thaw frozen pipes.


1-34. Water mains are usually cast iron, 8 inches or more in diameter. If the main is less than 8 inches in diameter, taps should be 2 inches or smaller. Use Figure 1-2 and the following steps to tap the water main:
Step 1. Dig to expose the pipe at the point where the tap is to be made. Dig as close to the top of the water main as possible.
Step 2. Clean all dirt and rust off the pipe at that point.
Step 3. Place the gasket of the water-main self-tapping machine on the pipe, and set the saddle of the machine on the gasket.
Step 4. Wrap the chain around the pipe, and tighten it to clamp the water main self-tapping machine to the pipe.
Step 5. Remove the cap from the cylinder of the machine, and place the combination drill and tap in the boring bar.
Tapping the Water Main
Figure 1-2. Tapping the Water Main

Step 6. Reassemble the machine by putting the boring bar through the cylinder and tightening the cap.
Step 7. Open the flap valve between the compartments.
Step 8. Start drilling the hole by applying pressure at the feed yoke and turning the ratchet handle until the drill enters the main.
Step 9. When the tap starts threading the hole, back off the feed yoke to prevent stripping the threads.
Step 10. Continue to turn the boring bar until the ratchet handle can no longer be turned without extra force.
Step 11. Remove the tap from the hole by reversing the ratchet. Then, back the boring bar out by turning it counterclockwise.
Step 12. Close the flap valve between the upper and lower compartments.
Step 13. Drain the water from the cylinder through the bypass.
Step 14. Remove the cap and drill tool. Place a corporation stop (Figure 1-3, page 1-10) in the boring bar, ensuring that the stop is closed.
Step 15. Repeat steps 6 and 7.
Step 16. Turn the ratchet handle to thread the corporation stop into the pipe.
Step 17. Repeat step 13.
Step 18. Remove the cap from the cylinder, and unbolt the boring bar from the corporation stop.
Step 19. Remove the lower chamber from the pipe.
Step 20. Inspect for leaks.
Step 21. If the corporation stop leaks, tighten it with a suitable wrench.


1-35. Curb and meter stops control the water entering the building. Figure 1-3 shows this installation.
Curb and Meter Stops
Figure 1-3. Curb and Meter Stops


1-36. After tapping the water main and inserting the corporation stop, install the curb stop in a suitable position. It is usually set in a cast-iron stop box to provide easy access in the water service between the curb and the building.
1-37. The stop box has a variable telescopic length for use on different grades. When the water service is copper, join the curb stop to the service piping with a compression joint. After installing the curb stop, run the water service line to the building and through the building wall to the inside of the basement. The water service line can be laid in the same trench as the sewer. The bottom of the water pipe at all points should be at least 12 inches above the top of the sewer line. The water pipe should be placed on a solid shelf excavated at one side of the common trench with a minimum clear horizontal distance of at least 12 inches from the sewer line. It must be placed in the ground at a level deeper than the maximum depth of frost penetration.


1-38. After running the water service lines through the side of the building and closing the holes around the service pipe with waterproof cement, install the water meter and meter stop.

Meter Stop

1-39. The meter stop is a ground-joint valve, which controls and shuts off the flow of water into the building. Place the meter stop as close to the service pipe entry as possible.

Water Meter

1-40. The water meter, installed near the meter stop, measures the amount of water used in the building.
1-41. Often the meter and stop are placed in a meter vault that replaces the stop box at the curb. In this case, place a stop-and-waste valve in the line where the water service enters the building.


1-42. The hot-water system consists of a water heater and a piping system. This system runs parallel to the cold-water pipes running to the plumbing fixtures (faucets) where hot water is desired. A standard detail drawing will show the water heater and standard storage-tank connections. The water heater is fueled by gas, oil, electricity, or possibly solar energy.


1-43. Water heaters are classified into four categories: range-boiler, gas, oil burning, and electric. See Chapter 5 for water heaters.


1-44. The pipes used in hot-water systems are similar to those used in cold water supply systems. Old hot-water systems used wrought-iron or steel pipe. Newer systems use chlorinated polyvinyl chloride (CPVC) plastic pipe, since CPVC resists corrosion. Copper is the most commonly used piping for distribution.


1-45. To size the hot-water main supply lines and the risers, follow the same procedure as for basic water supply.


1-46. Installation begins with a water-heating device and the main supply line from that device. Grade the hot-water supply to a centrally located drip cock near the water heater. Water for the fixtures at various levels throughout the building is taken from the main hot-water supply by fixture supply risers. Each of the risers should have a valve.


1-47. Buildings with a large floor area or with several floors need the supply of hot water to the fixture as soon as possible after the tap is opened. In a one pipe system, such as that used for cold-water supply, a lag occurs from the time the hot-water tap is opened until the water travels from the water heating device to the tap.


1-48. To overcome this time lag, use a two-pipe, circulating-water supply system (Figure 1-4). Hot water passes from the water heater through the main fixture supply risers and returns through a line to the water heater. This looped system circulates the hot water at all times. Warm water tends to rise and cold water tends to fall, creating circulation. The water within the loop is kept at a high temperature. When a tap is opened, hot water flows from the hot-water supply riser into the branch and out of the tap. The cold-water filler within the hot-water storage tank (water heater) has a siphon hole near the top of the tank. If reduced pressure occurs at point A, the siphon hole allows air to enter the cold-water filler. This breaks the vacuum and prevents back siphonage of hot water into the cold-water distribution system.
1-50. This circulating supply system (Figure 1-4) is an overhead-feed and gravity-return system and is likely to become air-locked. An air lock prevents circulation of the hot water. Since air collects at the highest point (B) of the distribution piping, the most practical way to relieve the air lock is to connect an uncirculated riser to the line at that point. The air lock is relieved when a fixture on the uncirculated riser is used.


1-51. Maintenance and repair of hot-water systems is similar to what was previously discussed.



1-52. Fire protection for buildings of fire-resistant construction is provided by fire hydrants. These are usually located at least 50 feet from each building or from the water distribution system within the building.
Circulating Hot-Water System (Two-Pipe)
Figure 1-4. Circulating Hot-Water System (Two-Pipe)


1-53. Automatic sprinkler systems are used for fire-resistant structures only when the value, the importance of the contents or activity, or the possibility of a fire hazard justifies a sprinkler system. Buildings of frame and ordinary construction that are more than two stories high and house tops will be protected by automatic sprinkler systems.


1-54. In a TO, there is always a chance the Army may have to take over the repair and operation of a municipal water system. Although most systems will be similar to those used in the US, problems can be expected in obtaining replacement parts and operating supplies. Sizes and dimensions of basic components can be expected to differ from those in the US and even require the use of metric tools. Also, certain nations may use different disinfecting methods than chlorine. Under these circumstances, the Army should consider hiring former local employees who are familiar with the equipment to operate and maintain the system.


1-55. After water is purified, it is released into the distribution system. The distribution of large quantities of water under tactical conditions will be by pipelines, trucks carrying bladders, and 5,000-gallon tanker trucks. Small quantities can be picked up from tank farms or storage and distribution points in 400-gallon water trailers or in refillable drums, 5-gallon cans, and individual containers.


1-56. Appendix B, Figure B-1, shows a water distribution system plan for a hospital area. The general location and size of the pipes are shown, together with the valves, sumps, water tank, and other fixtures. Generally, the symbols used on distribution-system plans are the same as those for water plumbing. (See Appendix B, Section II, for standard plumbing symbols.) The plumber who installs the system determines the location of the pipes and other equipment to suit the climate and terrain, and according to the National
Plumbing Codes.

It will be continue.

The Artikel taken from PIPING GUIDE. (


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