3
Vandalism
If the unit is installed where vandalism may be a problem, the assembly
should be protected and secured . On
1
⁄
2
" through 2" (15-20mm) units, the
handles of shutoff valves can be removed to discourage tampering . On
2
1
⁄
2
" through 10" (65-250mm) units, a chain can be looped through both
shutoff valve handwheels and locked in position to prevent tampering .
Testcock handles can also be removed . On backflow prevention assem-
blies installed in conjunction with fire sprinkler systems, a tamper switch
can be placed on the OS&Y shutoff valves that will trigger an alarm if an
unauthorized closure should occur .
A protective enclosure can be installed over the unit to discourage van-
dals . If an enclosure is used, it should be installed so that adequate clear-
ance is available for maintenance and testing . Consult local codes before
installing any type of protective enclosure .
Testing
All mechanical devices should be inspected on a regular basis to ensure
they are working correctly . The assembly should be tested at time of ini-
tial installation, after servicing or maintenance, and at least annually there-
after . Acceptable test procedures are published by Foundation for Cross-
Connection Control and Hydraulic Research at the University of Southern
California (USC), The American Water Works Association (AWWA), The
American Society of Sanitary Engineering (ASSE Series 5000) and the
Canadian Standards Association (CAN/CSA B64 .10) . Please consult the
regulatory authority in your area for more specific information .
MAINTENANCE MANUAL SERIES 850, 856, 870V & 876V 2
1
⁄
2
"- 10" (65 – 250mm)
Troubleshooting
Symptom #1
CauSe:
Solution:
Check fails to hold 1.0 psid minimum
A. Debris on sealing surfaces
Inspect and clean
B. Leaking shutoff valve
Inspect and clean, or repair
C. Damaged seat or seat disc
Disassemble and replace
D. Spring stem not moving freely
Inspect for debris or damage
Symptom #3 (DCDa only)
CauSe:
Solution:
Low flow passing through the
A. Mainline check fouled
Inspect and clean, or repair
mainline valve (DCDA only)
B. Bypass plugged (DCDA only)
Inspect and clean
Symptom #2
CauSe:
Solution:
Chatter during flow conditions
A. Worn or damaged parts
Inspect and replace