CHECK VALVE - A small device allowing water to flow in one direction only. A check valve has a spring which will hold the valve closed, and will not allow the water to flow out of the sprinkler until a pre-set pressure is achieved in the system. This spring will hold back water in a pipe that has as much as 7' to 10' change in elevation and is an excellent solution for slope applications. They can be integrated directly into the sprinkler head or can be stand alone devices.

FRICTION LOSS - Water flowing through the meter, valves, pipe, and fittings has considerable drag or friction. When the velocity of water increases, the friction loss increases. The friction reduces the available static pressure.

LATERAL (Lateral Line) - Non-pressure pipe running from the valve to the sprinklers. These lines are only under pressure when the particular zone is running.

MAIN (Main Line) - Pressurized pipe running from the P.O.C. to the zone control valves.

MANIFOLD - A group of valves. They are typically housed in a valve box, located in a landscaping bed.

P.O.C. - POINT OF CONNECTION - The sprinkler main line tie-in point.

POLY PIPE - Polyethylene is black, flexible pipe popular in areas that are susceptible to long freezes in the winter. An insert fitting with a house clamp or a compression fitting is used with poly pipe.

PRESSURE - Measured with a pressure gauge and expressed in pounds per square inch (PSI).

Static pressure is the PSI measured when no water is flowing through a closed system. Dynamic pressure is the PSI measured when the system is open, or water is flowing through.

PVC PIPE - The most common type of pipe used in areas with warmer climates. Generally white in color, PVC (polyvinyl chloride) pipe is more rigid than the black poly pipe, and requires the use of PVC solvents (glue). The pipe manufacturers also recommend the use of primer just prior to the application of the solvent. Some examples and descriptions of PVC pipe are as follows:

SCH 40 - A thick-walled pipe most commonly used under walkways and driveways. CLASS 200 - Piping with medium-thick walls and strength. This is the most common pipe used for residential sprinkler systems.

SHUT-OFF VALVES

Gate Valves have a wheel type handle. Several turns of the handle are required to turn off a gate valve. Gate valves are most commonly used on main line pipes with high water pressure or high water flow. Because several turns are required, they are easier to turn off and the potential for water hammer is reduced. Gate valves have a brass to brass seat and are not recommended for frequent use. Ball Valves have a single arm or lever that requires a quarter turn to turn on or off. This single action is convenient, but caution should be used and the valve should not be turned on or off too quickly while water is flowing, as damage could result. Ball valves have resilient seats and are better for frequent use applications. Hydro-Tech only uses ball valves for the POC.

SPRINKLER ZONE CONTROL VALVES

Manual Control Valves are not as common as they once were. The manually-controlled sprinkler system eliminates having to move a house-end sprinkler around from area to area, but the user does not have the convenience of the automatic system. Automatic Control Valves are used in conjunction with automatic timers and are a convenient, economical way of delivering water to lawns, plants and gardens. With an automatic system, the user does not have to worry about wasting water when they forget to turn the system off. Instead, just the right amount of water is delivered to each zone automatically.

VALVE - In a sprinkler system, there are many types of valves, but really only two families of valves-sprinkler valves and shut-off valves. Within those two families are a variety of valves. When discussing a sprinkler system, the term "valve" usually refers to an automatic control valve.

VOLUME - Expressed in GPM (gallons per minute), volume is used to describe either the amount of water available or the amount of water used.

WATER HAMMER - The surging of pressure which occurs when a control valve is suddenly closed. In extreme conditions, this surging will cause the pipes to vibrate or create a pounding noise. Water hammer is most commonly caused by fast-closing valves or pipes that have been sized too small causing high velocity water flow.