High-rise buildings present multiple challenges for water distribution due to the high pressures required to reach the top of the building. The high pressures in the lower levels of the building cause high-pressure drops across Pressure Reducing Valves (PRVs), over 100 PSI or more, creating the potential for cavitation within the valves.
Pressure Reducing Valve (PRV) Stations are an important component of a water-distribution system in a commercial building. The 2015 Uniform Plumbing Code Section 608.2 states that PRVs are required at any point where the system static pressure exceeds 80 PSI. Typically, this applies to mid- and high-rise buildings when the pressure boost required at the ground floor to serve the upper floors in the building is over 80 PSI. When designing a PRV Station, you must consider the station pressure drop, water flow, and safety devices.
Cougar USA’s mission is to make buildings work, so the people inside can do theirs. Over the last few months, this has become a personal mission of mine as well.
In November, my son Joey was born at Texas Children’s Hospital Pavilion for Women, and earlier this month had surgery in Legacy Tower to remove a benign cyst from his abdomen. Thanks to the amazing doctors and staff at TCH, Joey made a quick recovery – he definitely handled the surgery better than my wife Ashley and I did! After spending a few days recovering in West Tower, Joey was back smiling and being his happy self. Ashley and I feel very blessed that Joey’s case was minor compared to many families at Texas Children’s.
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Many commercial buildings in Houston have large water storage tanks to meet city plumbing code requirements. These break tanks provide water for fire protection pumps and domestic (potable) water pumps to supply the building. A major concern with break tanks in the building is the potential for flooding due to tank overflow. This is especially critical when the tanks are in a basement level.
Many commercial buildings use storage tanks for Domestic (Potable) and Fire Water Applications, especially in Houston where it is required by code. As water is used in the building, an automatic system is required to replenish the water and maintain a constant level in the tank. In domestic applications, this process can repeat multiple times an hour during peak demand loads. An automatic level-control system has two main components, Fill Valves and Controls.
Some call them House Tanks, others Break Tanks, Storage Tanks or Buffer Tanks. If you have been in the pump room of a building in Houston, you’ve seen these large water tanks, but why are they used? The Houston Amendments to the Uniform Plumbing Code states that upstream from a pump system, an atmospheric storage tank with an air gap between the tank and city water supply must be used. This applies any time the city water pressure is insufficient to supply a building for both Domestic (potable) and Fire Water applications and the addition of pumps is required.
In Houston, there was a construction boom in the 1970s and '80s, with hundreds of high-rise buildings adding to the skyline. Many of these buildings are still using the original mechanical systems for HVAC and pumping applications. Potential mechanical failure and energy savings are forcing building operators to choose between modifying existing equipment or replacing them all together.
According to ASHRAE 90.1, Domestic Water Booster Systems must shut down during periods of no flow demand. Operating pump systems when there is little or no demand wastes energy and increases wear and tear on the pump and piping system. While this sounds simple, it is one of the most challenging control sequences for a Booster System.
More than 60 years ago, the late Dr. Roy B. Hunter developed a system for calculating water loads in commercial buildings. The estimated water demand of fixtures (water closets, sinks, etc.) is given a value called Fixture Units which have an equivalent demand load in Gallons Per Minute (GPM). The Fixture Units and Demand Load relationship is known as Hunter’s Curve and is still the basis for plumbing system design today.