6
Instruction Manual
SECTION 2 - INSTALLATION
2.4 FOUR-FUNCTION VALVES (4-FV)
Your pump may be equipped with a 4-FV, or
standard discharge valve. If your pump is not
equipped with a four-function valve and you feel it
is needed in your application, it can be purchased
as an accessory. Contact your local LMI
®
stocking
distributor. The features of a 4-FV are listed below.
1.
Pressure Relief:
If the discharge line is over
pressurized, the valve opens sending solution
back to the supply tank.
2. Line Depressurization:
Opening the relief knob
provides line drain back to the supply tank.
4-FV prevents syphoning when
pumping into a vacuum such as the
suction side of a recirculating pump
w
4-FV prevents syphoning when
pumping downhill into
low or no pressure
3. Anti-Syphon:
Prevents syphoning when
pumping solution downhill or into a vacuum.
4. Back Pressure:
Supplies approximately 20 psi
back pressure to prevent overpumping when
little or no system back pressure is present.
Figure 6. Typical Installations Requiring the Anti-Syphon
Feature of a Four-Function Valve
