Watts LF909 Pequeno Serie Manual De Instalación página 7

Troubleshooting
PROBLEM
Valve spits periodically from
the vent.
Valve drips continually from
the vent.
Valve exhibits high
pressure drop.
No water flows downstream
of valve.
Valve does not test properly.
Valve quickly and repeatedly
fouls following servicing.
Performance of backflow
preventers affected during
winter season.
CAUSE
Fluctuating supply pressure.
Fluctuating downstream pressure.
Fouled first check.
Damaged or fouled relief valve seat.
Relief valve piston O-ring not free to move due
to pipe scale, dirt, or build
up of mineral deposits.
Excessive back pressure, freezing, or water
hammer has distorted the second check.
Electrolysis or relief valve seat or first check
seats.
Valve improperly reassembled.
Fouled strainer.
Valve too small for flows encountered.
Valve installed backward.
Manufacturer's test procedure not followed.
Leaky downstream gate valve.
Debris in pipeline is too fine to be trapped by
strainer.
Cold temperatures.
SOLUTION
Install a soft seated check valve immediately upstream of the
device.
Install a soft seated check valve downstream of the device, as
close as possible to the shutoff valve.
Flush valve. If flushing does not resolve problem, disassemble
valve and clean or replace the first check.
Clean or replace the relief valve seat.
Clean, grease, or replace the piston O-ring.
Eliminate source of excessive backpressure or water hammer
in the system downstream of the device. Use Watts No. 15
to eliminate water hammer. Replace defective second check
assembly.
In case of freezing, thaw, disassemble, and inspect internal
components.
Replace as necessary.
Replace relief valve seat or inlet cover.
Electrically ground the piping system and/or electrically isolate the
device with plastic pipe immediately upstream and downstream
of the device.
If valve is disassembled during installation, exercise caution when
reinstalling check springs in their proper location.
Clean strainer element or replace.
Install proper size device based upon flow requirements.
Install valve in accordance with flow direction arrow.
Clean or replace gate valve with full port ball valves or resilient
wedge shutoff valves.
Install finer mesh strainer element in the strainer.
Electric heat-tape wrap closely together around the valve body.
Build a small shelter around the valve with a large light bulb
installed and left on at all times.
If the supply line is not used during the winter, removal of the
complete body is the best. This creates an air gap to eliminate
any possible backflow.
7