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Plumbing systems must accomplish two important functions in buildings. They must provide a constant water supply for occupants, and for all equipment that requires it. At the same time, they must remove wastewater effectively to prevent health hazards. A well-designed plumbing system is necessary for a healthy building interior.
When designing a plumbing system, engineers analyze the water requirements of the building to specify an installation of the right capacity. Undersized piping and fixtures cannot deliver water at the required pressure and flowrate. However, oversized plumbing systems are more expensive, without offering any benefits in return.
Water conservation measures are strongly recommended by plumbing engineers. These measures not only reduce water bills, but also the pumping and heating costs related with water consumption. New constructions and major renovations provide an excellent chance to save water - designing an efficient plumbing system from the start is simpler than changing an existing installation.
In buildings that use natural gas for space heating and hot water, the plumbing design also includes gas piping and connections. Since natural gas is a highly flammable substance, having a safe installation is critical.
The specific requirements change by jurisdiction, but a plumbing design must normally be submitted by a licensed design professional. Once the project is approved, only a licensed plumbing contractor can perform the installation.
Selecting pipes of the right diameter is an important step in plumbing system design. Smaller pipes and their fittings have a lower cost, but an undersized pipe will restrict flow. However, oversized pipes are not recommended either - they are more expensive, their fittings also have higher prices, and the plumbing installation consumes more space than necessary.
Piping must be sized so that all plumbing fixtures in the building get enough pressure and flow. The calculations involved are complex, especially in larger facilities with many branches. However, thanks to modern design software, plumbing engineers can determine the pipe sizes that offer a reliable water supply at an optimal installation cost.
The following are some of the main factors considered by plumbing engineers when calculating pipe sizes for a building:
Since piping sizes affect pressure and flow, the calculation is an iterative process. Manual procedures take plenty of time, and in the past this was a limitation of plumbing design. However, modern design software can speed up the process significantly. There are simplified pipe calculations that use tables and rules, but they often result in oversized pipes, making the installation more expensive.
Water has an important role in fire protection, and a reliable water supply is critical when a fire occurs. Automatic sprinklers are very effective for fire protection, since they can extinguish most fires when they are still small. However, a sprinkler system is only reliable if the water supply is guaranteed when a fire occurs. Also, the piping that supplies water to sprinkler heads must meet the pressure and flow specifications provided by the manufacturer.
Plumbing design is also required for all fire protection systems that use standpipes, which are used by firefighters to connect hoses inside a building. In other words, a standpipe is similar to the fire hydrants found in streets, but designed for indoor use.
Fire protection systems may also need pumps to achieve the required flow and pressure. There are two main types of pumps used in fire protection:
Plumbing engineering has an important role in fire protection, especially when sprinklers and standpipes are involved. Building departments normally require these systems to be installed by a licensed plumbing contractor or fire suppression contractor.
