Automatic sprinklers are the most reliable and effective fire-protection devices available today—provided they operate correctly. To determine if a sprinkler system can adequately protect a property, underwriters should be familiar with the components, operation, and testing of the systems, as well as potential causes for failure.
Typical fire sprinkler system in a commercial building
A sprinkler system consists of the following components:
- A water supply and fire department connection
- Underground and aboveground pipes
- Valves and drains
- Alarms and test connections
Types of control valves
Because the sprinkler system connects to a water supply, the system needs some way to control flow when replacing a sprinkler or making alterations to piping. In many instances, occupancy changes require those types of modifications.
There are two categories of control valves:
- Indicating valves
- Nonindicating valves
Indicating control valve in closed position
A common type of indicating control valve is an outside stem and yoke valve, shown here in an underground valve pit
Examples of indicating control valves
Outside stem and yoke valve
The outside stem and yoke valve is the most common type of indicating valve. The valve operates by raising and lowering a gate that cuts off the water flowing through the valve casing. The gate connects to a large brass threaded stem with a circular threaded handle that connects to the yoke. As the operator rotates the handle counterclockwise, the stem extends further and further out of the handle, indicating the relative degree of the gate opening. As the operator rotates the handle clockwise, the threaded stem moves back into the valve and presents a lower profile. When the stem is no longer protruding beyond the handle, the gate valve is closed.
Outside stem and yoke valve in open position
Outside stem and yoke valve in closed position
Post indicator valve
Located outside a building, the post indicator valve extends up from the ground over a water supply main. As a detachable hand crank operates the valve, a tag connected to the stem reveals the word “open” or “shut” in a window on the side of the valve housing. You can lock the hand crank and the valve itself in position using a padlock or chain.
Post indicator valve in open position
Wall post indicator valve
The wall post indicator valve operates the same way as the post indicator valve, but it extends through the exterior wall of the building and is mounted horizontally. A wheel operates the valve, and you can see its status by the word “open” or “shut” as read through a window in the valve stem housing.
Wall post indicator valve in open position
Wall post indicator valve not maintained
The butterfly valve is hand-cranked open or shut by rotating a disc through the water stream perpendicular or parallel to the water flow. On top of the valve is a “tattle tail” that moves with the disc to indicate the position of the disc relative to the water flow. When the flag lines up parallel to the pipe, the valve opens fully. When it's perpendicular to the pipe, the valve closes fully.
Butterfly valve in open position
Butterfly valve in closed position
The main drain, or test valve, on an automatic sprinkler system primarily drains water from the system for maintenance. The main drain also tests the operation of the water supply for the sprinkler system. Testing determines that all valves controlling the system are open and that water is available.
Documented drain test results on the Automatic Sprinkler Grading Report (ASGR) can help evaluate the water supply. Current testing of the main drain is a mandatory part of the ASGR. Without the testing, the sprinkler system cannot receive credit.
Main drain located on the system riser
Control valves and drains summary
A well-designed sprinkler system is a highly effective method of minimizing property damage from a fire. But simply installing a sprinkler system doesn't guarantee adequate fire protection. Proper maintenance and testing ensure that the system will function as intended and suppress the fire with minimal water damage.
A few key points:
- Valves allow building staff to perform testing and maintenance on sprinkler systems.
- It's extremely important that all valves and drains have proper identification.
- Indicating valves visibly show when a valve is open or closed.
- A leading cause of sprinkler failure is not returning a valve to its open position once repairs and/or maintenance are complete.
Verisk has trained field staff to evaluate the design, installation, and condition of sprinkler systems anywhere in the country.
Report: Sprinkler Assessment Report