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Home-pool filters
Valve
types of swimming pool filters
The different
types of valves are the backwash valves, piston valves, rotary
valves, multiport valves, and pressure gauges and air relief valves.
There are two types of backwash valves. These are the piston and the
rotary. (The multiport valve is a type of rotary valve.) A backwash
valve is located on the filter and the purpose is to reverse the
flow of the water as the debris is flushed into a waste line or
sewer line. The backwash procedure is used in cleaning DE and sand
filters.
The side of the filter tank contains the piston backwash valve. As
water enters this valve it goes to the filter for its usual
operation. At this point water is filtered before it is returned to
the pool. The handle of the piston must be raised to the backwash
position. Do not alter the position of the piston when the pump is
on because it will force too much pressure in the pump, motor and
valve, and it may result in leakage. The water is forced into the
filter tank through the outlet port by the piston disks. In this
manner the water flows backwards through the filter while dirt and
debris are forced out of the tank and valve inlet port. The dirty
water is forced into the waste port once it is forced inside the
valve.
Vertical DE filters utilize the rotary valve. (This type of valve is
actually exclusive to DE filters.) The valve is held in place with
bolts that go through the bottom of the tank while a retainer ring
holds the valve body underneath the tank. A rotating internal rotor
underneath the filter tank changes the direction of the water while
a rotor gasket seal (O-rings) keeps the water from leaking. The
rotor must be rotated 90 degrees in order to start the backwash
process. (While the pump is running, DO NOT rotate the rotor as
leaks may occur.) Then water goes through the middle up inside the
grids as the DE and dirt are washed off of the grids while the water
flows from inside the grids to the outside. Water is forced back
through the rotor and out the opening which is marked backwash.
Sand filters use a multiport valve. This valve resembles a rotary
valve when it is taken apart. It is usually affixed to the top of
the filter tank, but it may be located on the side. The valve can
cause the water to flow in more than one direction. Debris is
averted from going back into the pool after backwashing because the
clean water rinses out the pipes before returning to its normal
circulation after the pump has undergone the backwash procedure.
A backwash hose must be attached to the backwash discharge port so
that the dirty water can be directed through the hose and onto the
lawn or street (if this is allowed). However, this is not necessary
if the backwash discharge port is plumbed directly to a drain or
sewer line. (One of these two procedures must be done regardless of
the type of valve you use.) Normally a backwash hose is 1-1/2 to 2
inches in diameter, up to 200 feet in length, and can be composed of
a collapsible plastic. Even a pool vacuum hose can function as a
backwash hose merely by utilizing a hose clamp.
Filters should contain a pressure gauge on top of the filter, or
mounted on the multiport valve. The gauge depicts 0 to 60 psi. The
pressure gauge is an important part of the filter because it will
inform you of operating problems in the filtering system. For
example, if the gauge reads ten pounds over the standard operating
process, the filter needs to be cleaned. When the pressure gauge
reads low it means that there is some type of obstacle in the water
passing through the filter; and when the pressure gauge indicates
high, the filter is dirty or there is an obstruction in the water
after the filter.
When the pump is operating and the pressure varies, the water level
could be low in the pool or spa or there could be a barrier in the
skimmer.
There are certain codes for commercial pools and spas. In some areas
a pressure gauge must be affixed to the incoming pipe as well as on
the outgoing pipe so that a person may compare the differences. The
two pressure readings are viewed by a health department inspector in
order to determine the cleanliness of the filter system. The optimal
difference is two to four psi.
In addition to the pressure gauge, an air relief valve may be
mounted on the T fitting. When the plug is opened, the air relief
valve enables air to flee from the filter after the system starts up
or when it has lost prime, causing air in the filter. In order for
the filter to work to its capacity, the air relief valve must
operate. It is, in this process, a very important aspect of the
filtering system.
Sight glasses may be installed in a line of pipe for the purpose of
viewing the efficiency of the cleaning system. They are the clean
portion of the pipe usually mounted on the backwash line as it comes
out of the backwash valve. When the water goes straight into the
drain, it enables a person to view the dirty water as it becomes
clean and stop the backwash when necessary.
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