Controls - CleaverBrooks FLX Operation, Service And Parts Manual

Chapter 7
E. CONTROLS
Relief Valves
The relief valve is a very important safety device and
deserves attention accordingly. Proper removal, installation
or handling of a relief valve is of primary importance.
Exercise care when removing, installing or handling a relief
valve to ensure proper operation, long service life, and to
ensure that the valve functions as designed.
WARNING
! DANGER
Improper removal, handling or installation
of a relief valve may adversely affect the
valve's operation, resulting in serious
personal injury or death.
Observe the following precautions when removing, handling
or installing relief valves.
• Use only flat jawed wrenches on the flats of the valve
• Do not use a pipe threaded into the outlet to turn a valve
• Apply only a moderate amount of pipe compound to male
threads
• Avoid over tightening, which can distort valve seating
surfaces
• Do not paint, oil or otherwise cover any interior or
working parts of the valve. A relief valve does not require
any lubrication or protective coating to work properly.
• Discharge piping must be properly arranged and supported
so that its weight does not bear on the relief valve.
• Handle with care a valve that has been removed from the
boiler. A dropped valve should be considered as damaged
until it has been inspected and passed by the valve
manufacturer's authorized representative.
WARNING
! DANGER
Only properly certified personnel such as
t h e r e l i e f v a l v e
representative should adjust or repair the
boiler relief valves. Failure to heed this
warning could result in serious personal
injury or death.
Relief valves should be operated only often enough to assure
t h a t t h e y a r e i n g o o d w o r k i n g o r d e r. F o l l o w t h e
recommendations of your boiler inspector regarding valve
inspection and testing. The frequency and method of testing
should be based on the recommendation of your boiler
inspector and/or the valve manufacturer, and should be in
7-4
m a n u f a c t u r e r ' s
Inspection and Maintenance
accordance with Section IV of the ASME Boiler and Pressure
Vessel Code.
Low Water Controls (Hot Water)
Most instances of major boiler damage result from operating
with low water. Since low water cutoff devices are set by the
original manufacturer, no attempt should be made to adjust
these controls in order to alter the point of low water cutoff.
If a low water cutoff should become erratic in operation,
immediately replace it or contact your local Cleaver-Brooks
authorized representative for assistance.
It is essential to verify proper operation of low water cutoff
devices as frequently as possible. However, it is impractical
to perform daily and monthly maintenance on some models
of the low water cutoff devices on a hot water boiler. Hot
water systems are fully closed. Daily or monthly maintenance
on some models of the low water cutoff devices would
involve draining the entire water content of the system and
would require makeup and additional feedwater treatment
that might not otherwise be necessary.
To verify the proper operation of float style low water cutoff
devices, the system must be drained. Remove the operating
mechanism from the bowl and check and clean the float ball,
internal moving parts, and the bowl housing. Also, check the
cross-connecting piping to make certain that it is clean and
free of obstruction.
It is impractical to blowdown the low water cutoff devices on
a hot water boiler, since the entire water content of the system
would become involved. Many hot water systems are fully
closed and any loss of water will require makeup and
additional feedwater treatment that might not otherwise be
necessary. Since the boiler and system arrangement usually
make it impractical to perform daily and monthly
maintenance of the low water cutoff devices, it is essential to
remove the operating mechanism from the bowl annually or
more frequently, if possible, to check and clean float bowl,
internal moving parts, and the bowl housing. Also check the
cross- connecting piping to make certain that it is clean and
free of obstruction.
WARNING
! DANGER
Safe operation of your boiler demands
periodic inspection and maintenance of all
low water cutoff devices. If controls do not
shut off the burner when the water level
drops below the safe operating level, or if
controls appear in poor physical condition,
or become erratic in operation, they must be
repaired or replaced at once. Failure to heed
t h i s w a r n i n g c o u l d r e s u l t i n s e r i o u s
personal injury or death.
If test-n-check valves are installed on the float style low water
cutoff devices, these controls can be tested by opening the
blow down valve. The test-n-check valves restrict water flow
750-177