Cleaver-Brooks CBH 40 - Chapter 5 Adjustment and Maintenance; Periodic Inspection; Water Level Controls

Chapter 5-Adjustment and Maintenance
Good housekeeping helps maintain a professional
appearing boiler room. Only trained and
authorized personnel should be permitted to
operate, adjust or repair the boiler and its related
equipment. The boiler room should be kept free of
all material and equipment not necessary to the
operation of the boiler or heating system.
Alertness in recognizing an unusual noise, im-
proper gauge reading, leaks, etc., can make the
operator aware of a developing malfunction per-
mitting prompt corrective action that may prevent
extensive repairs or unexpected down time. Any
steam, water or fuel leaks hsould be repaired as
soon as they are noticed. Leaks are wasteful as
well as hazardous. Include in the program, preven-
tive maintenance measures such as regularly
checking the tightness of connections, locknuts, set-
screws, packing glands, etc.
The air-fuel ratio should be checked often since
this will alert the operator to losses in combustion
efficiency which do not produce visible flame
changes. Variations in fuel composition from one
time to another may require re-adjustment of the
burner. A combustion analyzer should be used to
adjust fuel input for maximum operating efficiency
and economy.
B. PERIODIC INSPECTiON
Insurance regulations or local laws require a
periodic inspection of the pressure vessel by an
authorized inspector.
Chapter 2 contains information relative to this in-
spection.
Inspections of this type are usually, though not
necessarily, scheduled for periods of normal boiler
down time such as an off season. This major in-
spection can often be used to accomplish main-
tenance, replacements or repairs that cannot easily
be done at other times. This also serves as a good
basis for establishing a schedule for annual, mon-
thly or other periodic maintenance programs.
While this inspection pertains primarily to the
waterside and fireside surfaces of the pressure
vessel, it provides the operator an excellent oppor-
tunity for detailed inspection of all components of
the boiler including piping, valves, pumps, gaskets,
refractory, etc. Comprehensive cleaning, spot
painting or repainting and the replacement of ex-
pendable items should be planned for and taken
care of during this time. Any major repairs or
replacements that may be required should also, if
possible, be coordinated with this period of boiler
shutdown.
Replacement spare parts, if not on hand, should be
ordered sufficiently prior to shutdown.
Cleaver-Brooks boilers are designed, engineered
and built to give long life and excellent service on
5-2
the job. Good operating practices and con-
scientious maintenance and care will obtain ef-
ficiency
and economy from their operation and
contribute to long years of performance.
C. WATER lEVEl CONTROlS AND
WATERSIDE
OF PRESSURE VESSEl
The need to periodically check water level controls
and the waterside of the pressure vessel cannot be
over-emphasized. Most instances of major boiler
damag~ are the result of operating with low water
or the use of untreated (or incorrectly treated)
water.
Always be sure of the boiler water level. The water
column should be blown down routinely. Check
samples of boiler water and condensate in ac-
cordance with procedures recommended by your
water consultant. Refer to sections H and I in
Chapter 2 for blowdown instructions and internal
inspection procedures.
A typical water level control is mounted in the
water column. The control has 2 float actuated
mercury switches. One switch is connected to the
burner limit circuit and will stop the burner if a
low water condition occurs. On a steam boiler the
other switch is connected to the feedwater circuit
to energize a water pump or feeder valve to main-
tain water at the proper operating level.
Usually, the control is of the automatic reset type
and will remake the limit circuit when the water
level is restored. Some applications require that a
control be equipped with a manual reset mechan-
ism that must be manually reset before the burner
can be restarted.
Since low water cut-off devices are generally set by
the original manufacturer, no attempt should be
made to adjust these controls to alter the point of
low water cut-off or point of pump cut-in or cut-
out. If a low water device should become erratic in
operation or if its setting changes from previous
established levels, check for reasons and correct:
repair or replace as required.
Figure 5-l is a replica of the low water cut-off
plate attached to a steam boiler. These in-
structions should be followed on a definite
schedule. These controls normally function for
long periods of time which may lead to laxity in
testing on the assumption that normal operation
will continue indefinitely.
The controls' operation may be checked by stop-
ping the water supply to the boiler while the bur-
ner is operating at low fire. While under constant
attendance allow the water to lower at a normal
rate. If a control does not break the circuit to stop
the burner at the proper point then SHUT DOWN
THE BURNER IMMEDIATELY. Repair or
replace the control at once.