| Capital Projects Home Page |
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| Division 15 Mechanical |
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| 15-4 | Plumbing |
| A. | Design Criteria |
| 1. | Water Piping: |
| a. | Determine cold water service and building domestic hot and cold water demands for major buildings by the fixture unit method as outlined in the Uniform Plumbing Code. In addition to those given for sanitary fixtures, use 0.50 fixture unit for industrial cold water outlets over cup sinks in fume hoods and 1.0 fixture unit for each faucet at regular laboratory sinks with hot and cold water. |
| b. | Add known continuous demands to the total estimated demand. Discuss the use of a diversity factor with Capital Projects (CP). |
| c. | Size water piping with velocities not exceeding 7.5' per second and minimum of 35 pounds per square inch residual pressure at the highest, or last, fixture or hose rack. For copper pipe, size with velocities of 5' to 8' per second. |
| d. | Take particular care in designing and sizing of cold water piping to any shower, or shower room, where the use of adjacent flush valve fixtures could affect the pressure and cause excessive temperature fluctuations. Consider the use of a pressure balancing valve between hot and cold water supplies, or separate line from a point that would not be affected by flushing of fixtures. |
| 2. | Soil and Waste, and Vent Piping |
| a. | Size soil and waste piping by the fixture unit method as outlined in the Uniform Plumbing Code (UPC) or other acceptable method. |
| b. | Grade interior piping, above grade, at 1/4" per foot minimum; 1/8" is acceptable if the pipe size is increased to compensate for the 1% slope as required by Uniform Plumbing Code (UPC). |
| c. | Vent all sanitary fixtures as required by code. Discuss proposed combination waste and vent systems with Capital Projects (CP). Such systems must meet criteria set forth in Uniform Plumbing Code (UPC). |
| d. | Kitchen or Food Service Waste System: Design a separate waste system for any lower floor kitchen or food service where there are toilet rooms above. Keep this system separate and connect at a point in the building sanitary sewer system where a stoppage below the connection will not back sewage up to kitchen or food service floor drains or sinks. Obtain approval for use of backwater valves from Capital Projects (CP). |
| e. | Greenhouse Waste System: Design a separate waste system for all greenhouse floor drains, potting sinks, etc., that could receive sand, soil or similar planting materials. Extend this system to an interceptor before discharging into sanitary sewer system. See Division 15. |
| f. | Use corrosive-resistant pipe in any location where the waste may contain corrosives. See the Appendix for acceptable piping materials. Keep such waste and vent system separate from the building plumbing soil, waste and vent systems to a point outside the building. In buildings with minor isolated points of corrosive use, discuss the method of handling with Capital Projects (CP). |
| g. | Use gravity flow for all building drainage systems. Where this appears to be impractical, discuss installation of pumps with Planning, Design and Construction (CP) and obtain approval before proceeding with design. |
| h. | See Division 14 for elevator pit drains. |
| 3. | Laboratory Piping: |
| a. | Size piping for compressed air, vacuum, gas, industrial hot and cold water in accordance with the laboratory pipe sizing standards in the Appendix. This chart includes a diversity factor in the number of outlets permissible on a given pipe size. |
| b. | Discuss sizing of laboratory pipe for other gases such as oxygen or nitrogen with Capital Projects (CP). |
| 4. | Size building distribution systems for all compressed gases and vacuum using a maximum of 5% loss of initial pressure to furthest point of use under maximum demand. |
| 5. | Show a separate natural gas service to any room or area where gas burners are used with other gases, or air, under a greater pressure, such as a glass-blowing room. Provide Reliance Regulator Company, type Y-183 diaphragm-operated check valve, or equal, to prevent a backflow of the higher pressure gas into the building natural gas distribution system. Vent check valve discharge to a safe point. |
| 6. | Hot Water Supply |
| a. | When selecting steam-fired instantaneous water heaters, the following fixture demands may be used in estimating the required heating capacity. |
| Domestic Hot Water | Gallons per minute | Industrial Hot Water | Gallons per minute |
| Lav | .10 | Lab Sink | .25 |
| Sink | .25 | Lab Outlets | .10 |
| - | - | Dark Room Sink | .25 |
| Discuss diversity factor with Planning, Design and Construction (CP). | |||
| b. | Add known industrial hot water demands, such as washers, process work, animal room cleaning, etc., to the total fixture demand. |
| c. | Provide hot water temperature regulation to showers, with thermometers on hot and regulated water, for setting maximum temperature. |
| d. | See this division for water heater information. |
| e. | Provide pumped circulation for all hot water systems. |
| 7. | Rainwater Leaders and Storm Drains: Compute rainwater quantity on the basis of 1.5" rainfall per hour minimum (.935 gallons per hour/square foot horizontal drainage area). Size all piping per UPC. |
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