A feature that was designed to help mitigate water hammer. By constricting the flexing of the diaphragm, the valve is made to open and close slower, which helps control the abrupt changes in velocity that cause the hammer or knocking in pipes. If the zone is under high pressure and misting at the sprinkler, the flow control can be used to get the water droplet size larger. A larger, heavier drop of water is more likely to land on target, rather than being easily blown away.
Some advanced valves have this feature built in, but other manufacturers offer this feature
as an add-on part. The pressure is reduced without a subsequent reduction in flow. We feel
that high pressure in a residential or light commercial system should be regulated at the
beginning of a system with a pressure regulating valve, but larger systems sometimes have to
be designed with higher pressures to accommodate longer mainline lengths, elevation
changes, etc. This is when pressure regulation at the valve is crucial. Sprinkler heads
operating at pressures higher than recommended will turn the water into a fine mist, which is
easily blown away before it reaches it target. The goal is to have the water traveling through
the air in a nice, fat droplet that's less likely to be blown off course.
The in and out sockets are configured at a 90 degree angle. A straight configuration is also
called a “Globe Valve” The angle configuration is typically used when the main line has to
be quite deep and the valve needs to be located closer to the surface. Pressure loss inside the
valve is slightly reduced in this configuration. Also consider that there is usually the
elimination of one elbow, which also prevents more friction loss. Some 1.5” valves have a
threaded plug on the bottom that converts a globe valve to an angle valve.
Atmospheric Vacuum Breaker
The H configuration valve is a combination of valve and backflow prevention device. These
are commonly referred to as “anti-siphon valves.” These valves should never be installed
below ground level, in a box or not. They also should be at least 6” higher than the highest
usage point (sprinkler head or drip line.) Check your local codes for details.
Extremely durable models are made by most manufacturers. Plastic valves typically have
pressure ratings around 150 PSI, but a brass body can handle up to 220 PSI.
Jar Top Configuration
Several valve models also come with a bonnet that screws onto the valve body. Designed for
ease of service, one can can take this valve apart without any tools for a quick flushing or
Not only are some valve models designed for reclaimed, recycled, or “dirty” water, they also
provide purple versions for easy identification.
These advanced features help keep the internal workings of a valve scrubbed clean of any
contaminants. This is a feature generally found on more expensive valves designed for
commercial or municipal use.
DC Latching Solenoids
One can adapt a normal AC valve to work with DC battery powered timers by using a
latching solenoid. A normal AC solenoid is held open by the timer during the entire run time
of that zone. In contrast, a DC timer will send one signal which latches the solenoid open, then
at the end of the zone's run time, another signal is sent to the solenoid which closes it.