Glossary Of Terms - Hunter Sprinkler System Design Handbook

ARC – Describes how far around in a circular pattern a sprinkler will rotate
or spray. A sprinkler with a 90° arc would spray a quarter circle.
BACkFLOW PREVEnTER – A device installed between the P.o.C. and the
sprinklers that is designed to prevent the backflow of contaminated water
into the drinking water. Different countries require different types of back-
flow preventers. The user should check with their hunter dealer or local
permitting agency for the type of backflow device approved for their area.
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 2 to 3 meters change in elevation and is an excellent solution
for slope applications.
COnTROLLER – Also known as a timer, the part of an automatic sprinkler
system that determines when a valve will turn on and how long it will oper-
ate. The timer sends a low voltage signal to the valve, which will then open
for a predetermined amount of time allowing water to flow to the sprin-
klers. What size timer to purchase is determined by how many zones are in
the sprinkler system.
FLOW – Expressed in liters per minute (l/min) or in cubic meters per hour
(m3/hr), flow is a measurement of the volume of water moving through a
pipe or sprinkler component over a specific amount of time.
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
dynamic pressure.
HEAD-TO-HEAD – This phrase describes the correct placement of spray
heads and stream rotors. one sprinkler must be placed so that it will spray
another sprinkler (or 50% of the adjusted diameter). This provides for com-
plete coverage and prevents dry spots.
LATERAL (lateral line) – non-pressure pipe running from the valve to the
sprinklers.
LOW HEAD DRAInAGE – Water left in the pipe after a valve is turned off
that is gently flowing out of a low elevation sprinkler head. low head drain-
age can be corrected through the use of a check valve.
L/MIn (lITERS PER MInuTE) – The available l/min must be known before
a sprinkler design can be completed. Sprinkler heads have different l/min
requirements. The total l/min of all the sprinkler heads on one zone should
not exceed the available l/min.
MAIn (MAIn lInE) – Pressurized pipe running from the P.o.C. to the zone
control valves.
MAnIFOLD – A group of valves.
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 hose clamp
or a compression fitting is used with poly pipe.
PRECIPITATIOn RATE – Expressed in mm per hour, precipitation rate is
the rate at which water is being applied. Matched precipitation means all of
the sprinklers in the area are placing about the same amount of water on a
given area. Different types of sprinklers should not be installed in the same
zone. large area sprinklers and small area sprinklers may use the same
lPM, but because the size of the areas they cover is not the same, the mm
per hour of water applied is very different.
PRESSURE – Measured with a pressure gauge and expressed in kPa or
Bars. Static pressure is the kPa measured when no water is flowing through
a closed system. Dynamic pressure is the kPa measured when the system is
open, or water is flowing through.
PROGRAM – A program is information the user enters into the timer's
memory that determines when the system will water. A program for an
automatic sprinkler timer contains three pieces of information: what days
to water, what time to start watering all zones, and how long each zone will
water.
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Glossary of Terms

PVC PIPE
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.
RADIUS
5.2 meter radius means that the water will spray out as far as 5.2 meters.
ROTORS
and rotate slowly in a circular pattern, streaming out water to areas as small
as 5 meters and as large as 23 meters or more. Rotors fit into the "large
area sprinklers" category.
SPRAY HEADS
water. These heads have a radius of 5.2 meters and shorter. Spray heads fit
into the category of "small area sprinklers."
STATIOn
ing zone are connected by pipe to a valve, which is wired to a station on
the controller. A 6-station controller (also called a timer) can control from
one to six valves.
TIMER
TREnCH
When digging in the yard most people will dig without concern to about a
10 cm depth. At 15 cm they begin to dig more carefully, as they know there
are utilities buried in their yard. Installing the lateral pipes at 15 cm to 20
cm helps to avoid broken pipes due to weeding or the planting of annual
color. The main line is usually installed before the lateral lines and should
be deeper, allowing the lateral lines to be installed at the stated depth. As
an added note, install the low-voltage wires in the same trench below the
main line pipe to help protect the wires.
VALVE
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.
SPRInkLER ZOnE COnTROL VALVES
MAnUAL COnTROL VALVES
The manually-controlled sprinkler system eliminates having to move a
hose-end sprinkler around from area to area, but the user does not have
the convenience of the automatic system.
AUTOMATIC COnTROL VALVES
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.
VOLUME
describe either the amount of water available or the amount of water used
(see flow).
WATER HAMMER
valve is suddenly closed. In extreme conditions, this surging will cause the
pipes to vibrate or create a pounding noise. Water hammer is most com-
monly caused by fast-closing valves or pipes that have been sized too small
causing high velocity water flow.
WIRE
used to connect the automatic control valves to the controller. The most
frequently used wire for the home sprinkler system is multi-strand. Color-
coded, multi-strand sprinkler wire has several coated wires together in one
protective jacket. It is a good idea to install extra wires for future expansion
of the system.
ZOnE
– The most common type of pipe used in areas with warmer
– how far out from the sprinkler the water sprays. A nozzle with a
– Gear-driven sprinklers that shoot out a solid stream of water
– Sprinklers that emit a fan-type spray of small droplets of
– A term used when discussing controllers. Sprinklers in a water-
– See "Controller"
– lateral line trenches should be at least 15 cm to 20 cm deep.
– In a sprinkler system, there are many types of valves, but really
are not as common as they once were.
are used in conjunction with automatic
– Expressed in liters or cubic meters (m
– The surging of pressure which occurs when a control
– In an automatic sprinkler system, low voltage direct burial wire is
– A zone is an area to be watered by one sprinkler valve.
), volume is used to
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