Increasing the spacing of the sprinklers or using sidewall sprinklers can increase the flow demand significantly beyond 26 gpm. Of course, this can vary depending on the requirements of the system and the person doing the design and hydraulic calculations. So the most common demand for two sprinklers flowing is going to be 26 gpm. The minimum pressure and flow for this sprinkler is 7 psi at 13 gpm for spacing up to 16 feet by 16 feet. The most commonly used residential sprinklers are 4.9 K-factor pendant sprinklers. The National Fire Protection Association (NFPA) 13D Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes requires the system be sized to provide flow for the two most hydraulically demanding sprinklers located in the same compartment. While there can be some variation, the most common maximum flow rates for each size of meter are: 20 gpm for a 5/8-inch or 5/8-inch by 3/4-inch meter 30 gpm for a 3/4-inch meter and 50 gpm for a 1-inch meter.įlow rates with residential sprinkler systems Therefore, when evaluating water meters for a fire sprinkler system, look at the maximum intermittent flow rate, not the continuous one. The typical 10-minute duration expected for a residential sprinkler flow, or even 30 minutes of a higher flow, fall well within the “intermittent” category. The maximum intermittent flow listed is for brief periods of flow. That said, there are two important numbers regarding the flows available from any residential water meter: 1.) the safe, maximum “intermittent” operating range and 2.) the recommended maximum rate for continuous flow. Most have similar ratings for flow restrictions based on American Water Works Association (AWWA) standards. PD meters have very similar characteristics across brands and models.
Alternative means to achieve the same results will be imperative. As residential sprinkler system installations continue to increase, the use of these devices will need to be seriously reconsidered. On top of that, there are multiple options for fittings and valves that can be used in a meter setter or yoke, almost all of which are small sizes and have significant pressure losses as well.ĭepending on the components used and the manufacturer, a 3/4-inch meter setter can lose as much as 25 psi of pressure at standard residential sprinkler system flow demands. They can have very small pipe or tubing incorporated into their makeup which, on its own, can seriously restrict the pressure and flow. While helpful for water purveyors, they can be troublesome for fire sprinkler systems. The purpose of meter setters or yokes in a meter assembly is to elevate the meter to a height that makes it more convenient for reading and servicing. Meter setters or yokes in fire safety systems
Due to this decrease in accuracy, water purveyors tend to prefer the smaller meter sizes to avoid lost water and revenue (typically from slow leaks or running toilets). While PD meters are very accurate for smaller sizes, such as 5/8-inch and 3/4-inch, that accuracy tends to decline as the meter size increases to 1-inch and larger. The most common meter used in residential applications is the positive displacement (PD) meter. It’s also important to understand the limitations of common components installed in the water supplies to these systems, such as pressure reducing valves, check valves and water meters.Ī water meter typically determines water usage by measuring displacement or velocity, and the technologies used for these two techniques vary. More fire sprinkler systems are being installed in one- and two-family homes and townhouses, so it’s important to understand their requirements. Get Fixtures/Materials articles, news and videos right in your inbox! Sign up now.