Nova-Tech LMI Roytronic Excel Series AD Metering Pump - Manual (Page 11)

11
INSTALLATION
3.4 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 solu-
tion back to the supply tank.
2. Line Depressurization: Opening the relief knob provides line drain back to the supply
tank.
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.
Typical Installations Requiring the Anti-Syphon
Feature of a Four-Function Valve
4-FV prevents syphoning when
pumping downhill into
low or no pressure.
4-FV prevents syphoning when
pumping into a vacuum such as the
suction side of a recirculating pump.