Waterflow detectors, which are installed in fire alarm sprinkler systems, monitor the flow of water to sprinkler heads with a specially designed paddle. They are useful as security and safety tools because they eliminate the possibility of sprinkler malfunction. If a sprinkler head is activated and water begins to flow, for example, the waterflow detector will send a signal notifying the fire alarm control panel.
Vane or paddle type waterflow detectors are used to detect the flow of water in a wet pipe sprinkler system and to send an alarm signal. Waterflow detectors can be mounted to vertical upflow or horizontal-run distribution pipes in wet pipe sprinkler systems.
The detectors include a plastic vane or paddle, which installs through an opening in the wall of the distribution pipe. When the flow of water is greater than 10 gallons per minute, the vane or paddle deflects, which produces a switched output, usually after a preset time delay.
To minimize false alarms due to pressure surges or air trapped in the sprinkler system, a mechanical delay is often used to postpone switch activation. Often referred to as a retard, this delay takes the place of the previously mentioned retard chambers in wet pipe systems. If water flow decreases to four gallons per minute or below, the timing mechanism will reset to zero; delays do not accumulate. Time delays are adjustable from zero to 90 seconds.
Typically, waterflow detectors are equipped with dual SPDT (Form C) switches for activation of an alarm panel and alarm bell, or an A/V device. When a waterflow detector is connected to a listed sprinkler/fire alarm control panel, the initiating circuit must be non-silenceable. Waterflow detectors are designed to be installed in a variety of environments and are approved for both indoor and outdoor applications. U-bolt type waterflow detectors are designed primarily for use in commercial applications.
T-tap type waterflow detectors are also available and are primarily used in residential applications and branch line signaling in larger systems. The only differences between U-bolt and T-tap style waterflow detectors are the methods by which they attach to the pipe. T-tap style waterflow detectors also are available without a time delay mechanism.
Super Bowl fumble: seats unsafe
When it comes to adapting to building changes, fire and life safety goes beyond the building systems in place. The National Football League learned that lesson about a temporary seating section that was installed at the stadium to accommodate Super Bowl 2011 fans. Hours before the Green Bay Packers played the Pittsburgh Steelers about 1,250 temporary seats were deemed unsafe. The NFL scrambled to find new seats for about 850 people. The remaining 400 fans were forced to watch from standing-room locations around the stadium.
The events leading to the announcement show how fire and life safety goes beyond precautionary measures. In the process of getting a permit for the seating from the city of Arlington, several concerns were raised that needed to be corrected prior to the day of the event:
- Structural columns appeared to interrupt some aisle stairs.
- Some sets of plans did not have an engineer's seal or signature.
- Guardrails were not shown for stair landings.
- Handrails were not shown in some areas.
- Required headroom clearances were not shown.
- Information for stairways into and out of the seating areas was missing.
In addition, fire officials required proof that an engineer had signed off on the plans within two days, and they wanted firefighters assigned to oversee temporary seating sections for the safety of the people watching the game from those spots.
Undoubtedly, the temporary seating section snafu, which has been called a "horrible mistake," angered misplaced fans. Like it or not, safety standards are in place for a reason and life safety is always a core critical component to the protected premises.
Jackie Lorenty is the marketing manager, AMCO/Fire Sprinkler Business Unit, System Sensor U.S.