Case Study: Inline Flow Switch Prescribed for Hospital

The maintenance of sprinkler systems can be a major, sometimes costly, task for building owners, but it is a crucial factor in a fire-protection system's performance and life span...

By Staff April 1, 2002

The maintenance of sprinkler systems can be a major, sometimes costly, task for building owners, but it is a crucial factor in a fire-protection system’s performance and life span.

The benchmark for this procedure is NFPA 25, Standard for the Inspection, Testing and Maintenance of Water-Based Fire Protection Systems , and a major facet of this standard is the testing of a system’s water flow, which facilities are required to regularly test. Conventionally, this involves draining the water from a system’s pipes. But during the past six months, Hinsdale Hospital in Chicago’s west suburbs, has adopted a new, more cost-effective and convenient method that incorporates an inline flow-switch tester into the compliance procedure. A modern renovation

Founded in 1904 in a small, wooden building, Hinsdale Hospital has since matured into a modern 426-bed medical facility. One of the hospital’s most recent upgrades was completed in December of 2001, when the hospital unveiled a completely renovated pediatric unit.

Although the most readily visible feature of the $1.5 million project is the interior decor, much of the innovative planning went into the behind-the-scenes infrastructure, of which the inline flow-switch testing capability is an important part.

The system uses a recirculating pump to flow existing water within the sprinkler-system riser, activating the paddle of the flow switch and thereby simulating the activation of a sprinkler head. The detector then sends a signal to the master control panel, satisfying NFPA 25 requirements.

Each testing unit activates via a key switch wired to its pump. The system is conducive to wiring key switches together, which allows interconnection of multiple units and permits all networked units to be tested from one location. With a single turn of the key, all interconnected units are activated to test the individual flow switches of each. Also, because each unit requires a switch box, any single key switch can act as the master for all units.

“When I first learned I could perform NFPA testing by turning a key—without draining the water from the sprinkler system—I had to try it,” says Robert Funk, Safety Specialist and Fire Alarm Technician at Hinsdale Hospital. “Being a health-care facility, our utmost concern is our patients’ well-being, and having to drain and dispose of 30,000 gallons of stale water from the sprinkler systems each year was more than inconvenient.”

According to Funk, NFPA 25 requires that the hospital conduct quarterly tests of all 74 zones—each one holding about 100 gallons of three-month-old water. “When we would drain it, the odor would spread and it could get pretty bad,” he explains.

Using the conventional draining method, crew members coordinated each test by radio. This required that the inspector’s test valve connection be opened to simulate activation of a sprinkler head. This would trip the detector, activating an alarm at the control panel. The drawback, besides odor problems, was that water had to be jettisoned from the sprinkler system through the test valve to a nearby utility sink.

“Since all of our zones are filled with straight tap water, we drained to the main sewer line. There were no other options,” says Funk. “With this new system in place, we test by recirculating the water, not draining it.”

“We now use two guys for testing—one at the flow-switch tester, the other at the control panel. Being able to test with a key switch saves the hospital a lot of time and effort. We also save on water—each time we had to drain the system it was costing us to refill them.”

But the most significant benefit, explains Funk, is improved hygiene. Because the facility is a hospital, this is a very important consideration and the reason that, after a couple of test periods, this testing system is being specified for all sprinkler projects on the medical campus. A fit for retrofits

Another major factor in the continuing choice of these inline flow-switch testers is their ability to easily adapt in retrofit installations.

“The installation was very clean and easy,” says Funk. “The staff plumber cut and fit the pipe using the template and mounted the unit to the riser; then I did the electrical work. I ran regular 110 [volt] power from the junction box to the detector and the key switch box, and we were done. It took just a couple of hours,” he says.

The flow-switch testers install on a sprinkler system riser, and the test assembly mounts on any clear pipe span of the appropriate nominal size. The testers can be installed for either a vertical up flow or a horizontal run.

Retrofit models of the flow-switch tester are available for risers sized between two inches and eight inches, and are compatible with schedule-10 through -40 steel pipe. For new construction applications, assembled manifold models install on pipes sized between 2 and 4 in.—in both domestic and Canadian configurations—and are compatible with schedule 10 steel pipe.

For more information on Zonecheck flow-switch testers from System Sensor, visit and enter reader service # 101.