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| Float Valve Selection & Installation |
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| NOTES FOR TROUBLE-FREE OPERATION: |
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- Insure that the Valve, Stem, and Float used is rated for your Maximum Inlet
Pressure and GPM Flow Rate. Check minimum Stem Length and minimum Float
Ball size. This may vary according to your application and maximum inlet
pressure.
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- All Bob® and
Bobby®assemblies are shipped
standard with the minimum recommended Stem and Float sizes for reliable and accurate
liquid level control up to the maximum rated pressure. Sometimes you can
use a shorter stem with a larger float or vice versa, however, not all
combinations are reliable at all pressures.
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- In non-standard assemblies, if you see that float is completely submerged
without shutting off, or if the float "Bounces" all by itself
without stopping, it usually means that the float is too small or the stem
is too short to work reliably at that pressure. If your particular application
requires a shorter stem, bent stem, and/or smaller float than recommended,
it will reduce the amount of leverage or buoyancy available to close the
valve, thus lowering the maximum rated inlet pressure. This can be compensated
for by using a pressure regulator to reduce the inlet pressure. Instead
of modifying the assembly or installing a regulator, try selecting a smaller
standard assembly that fits your available space, or a smaller orifice
size to gain reliable shut-off at higher pressures. Keep in mind that reducing
the inlet pressure or selecting a smaller orifice size will also reduce
the GPM Flow Rate. Another option might be to consider using two smaller
valves instead of one larger valve to meet your GPM and space requirements.
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- An increase or decrease in the inlet pressure at the valve will usually
cause a slight increase or decrease in the water level setting at shut-off.
The water level at shut-off reaches maximum height at the maximum possible
inlet pressure provided. When the inlet pressure changes, the amount of
change in the water level is related to the volumetric displacement (Size
and Shape) of the float. This is a normal property of float valves. Maximum
accuracy and repeatability is obtained when the inlet pressure remains
constant. Where you have changing inlet pressures, be sure that your application
design allows for slight changes in the water level at shut-off.
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- Always insure that the float valve body is mounted rigid with respect to
the water surface. If the tank wall, supply pipe, or mounting bracket is
able to flex or move, it may cause the valve to vibrate, oscillate, or
"sing" very loudly. As the valve starts to close, the pressure
increases causing the valve body to flex away from the water surface. When
the valve body moves away, the valve opens more. As the valve opens more,
the pressure decreases causing the valve body to flex back to it's original
position. And when the valve body returns to it's original position, it
starts to close again, repeating the cycle of oscillation. A rigid mounting
system prevents the potential for this kind of vibration or oscillation
to occur.
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- Your tank or reservoir should always include provisions for some kind of
overflow drain system capable of handling the maximum GPM flow rate. Dirt,
physical damage, excess pressure, loose or improper adjustment, normal
wear, or mineral deposits built up over time may one day prevent the valve
from fully closing. An overflow drain system will prevent the possibility
of unexpected flooding should this occur.
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- To prevent overflow during normal operation, your overflow drain should
be high enough above the set water level to accommodate the water level
at your maximum inlet pressure, and also any surface turbulence. In closed
loop pump systems, you may also want to increase the overflow drain level
higher above the set water level. This helps to prevent or reduce overflow
by allowing extra storage capacity to accommodate additional liquid in
your loop system that might drain back to the reservoir or tank when the
pump is stopped.
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- In closed loop pump systems where water is evaporating, minerals like calcium
remain and concentrate in your system. You may want to set up a separate
water bleed-off system to help prevent or reduce build-up of excess minerals
in your reservoir or tank. You may also want to decrease the overflow drain
level closer to the set water level. This allows any additional water in
your loop system that might drain back to the reservoir or tank to bleed
automatically from the overflow drain when the pump is stopped.
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- Normal wear over the life of the valve may cause the water level setting
at shut off to gradually increase slightly, possibly requiring occasional
re-adjustment.
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- Slight leakage or dripping around the valve plunger or cup seal when the
valve is in the open position is normal for all float valves of this type.
If the cup seal was tight enough to prevent any leakage or dripping at
the plunger, the plunger may bind and stick open or closed. The cup seal
prevents excessive spray from occurring around the plunger and directs
the flow to the valve outlet without causing the plunger to bind. Water
cannot drip from around the plunger when the valve is fully closed.
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- A float valve of this type closes gradually rather than "snap action"
ON/OFF. Slight leakage or dripping from the outlet as the water level reaches
the shut-off point is usually normal unless the seat or disc is worn. If
the float arm or stem is lifted slightly and the dripping stops, it indicates
that the seat and disc are functioning normally, and the water level is
just not high enough yet to achieve full shut-off.
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- Insure that the Valve Body, Disc, Cup, Stem, and Float materials are compatible
with the temperature and type of liquid controlled.
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- Consider carefully where the valve will be mounted because it's best to
avoid bending the Stem if possible. Bending the stem too much shortens
the effective length of the stem which may reduce the amount of leverage
available to close the valve. Instead, adjust liquid level with Short Arm
and Thumb Screw or adjusting screw. Again this may vary according to your
particular application and maximum inlet pressure. For an extra charge,
we may be able to supply custom bent stems if you can specify your exact
requirements.
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| GENERAL INSTALLATION INSTRUCTIONS: |
- Attach valve to tank wall or pipe fitting and connect valve INLET to water
supply.
- For Horizontal Installations, insure that Valve Body is mounted parallel
to the water line, and the Valve OUTLET is straight downward for Bind-Free
operation.
- Use wrenches on any flats provided to minimize distortion of the valve
body during installation.
- Screw stem and float to short arm.
- Rotate arm and stem for desired water level, then tighten short arm thumb
screw.
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| Avoid over-tightening during installation, however, use general
care to..... |
- Insure that Thumb Screw or adjusting screw is tightened securely.
- Insure that the Float, Stem, and Short Arm are tightened securely.
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