IOM - DOUBLE ECCENTRIC BUTTERFLY VALVES
UNIWAT® VF791
©COMEV
AL
V
AL
VE SYSTEMS
Technical Dept. Ref. IOM - DOUBLE ECCENTRIC BUTTERFL
Y V
AL
VES, UNIW
AT® VF791 - Ed.20/07
Comeval V
alve Systems reserves the right to alter any technical data contained in this Manual without prior notice. Regularly updated data on www
.comeval.es
- Ensure valve surface is in good condition and retouch coating protection when needed.
- Check for tightness in valve connections and stem sealing. If leakage in valve connections, retighten flange bolts cros
-
swise and gradually if necessary until leakage elimination. If leakage persists, correct alignment and centring of the valve
should be checked, and surfaces should be thoroughly cleaned. If contact surfaces are irreversibly damaged replace
them. If valve leaks through the stem please contact us for advice.
- Once the valve installed, make an initial opening and closing operation to check its proper operability, without additional
tools.
- We recommend control operation in the range of 15º to 75º disc open angle only. Leaving the disc near to closed posi
-
tion can lead to premature wear.
- In case of risk of media freezing inside the valve, take due measures to avoid it.
For worm gear adjustment:
7. CARE AND MAINTENANCE
The operator must define maintenance and maintenance-intervals to meet requirements.
- Check for body, seat and connections tightness, and valve smooth operation without additional tools.
Page 5
ATTENTION!
- In the event of infrequent use, operate the valve as frequently as possible to avoid deposits of dirt and valve
blocking.
- Before disassembling the valve, note chapters 3, 10 & 12.
- When using the valve as an end seal, the employers’ liability insurance association specifies the use of a
safety precaution such as a plug-in disc, blind flange, Before starting maintenance work on an end valve with a
free stem end, you must mount a blind flange.
- Only carry out maintenance work in the pipework when the valve has been secured from operation (in case of
actuator, ensure it has been disconnected from the mains supply and secured from reactivation).
- When the valve is operated, there is a crushing hazard between the disc and the seat area. Ensure the valve
is not under operation in case hands are introduced inside the valve.
- Check the valve surface inside and outside and retouch coating protection when needed. If advanced corro-
sion or erosion is observed, double check service and valve features and replace the valve properly.
- A butterfly valve is not self-locking, so that the operating device (lever, gear or actuator) should only be disas
-
sembled after pressure release.
ATTENTION!
- Worm gear has two allen screws to adjust the end positions. The one at left side is to adjust the open position.
The one at right side is to adjust the closed position. By loosening the screw you allow further turning of the valve.
Valves delivered with assembled worm gear are already adjusted at factory. A bad adjustment of these screws
could lead to valve wrong function.
Adjusting screw
at close
Adjusting screw at open
Blocking
screw
Blocking screw
