750-91 (revised 2009)
Model CB-LE Packaged Boiler Manual
8-3
8.3 — Water Level Controls
Refer to Section 8.17 for instructions on properly closing rear heads.
The flue gas outlet and stack should be inspected annually and cleaned as necessary. Commercial firms are available
to perform the work. The stack should be inspected for damage and repaired as required.
The fireside should be thoroughly cleaned prior to any extended lay-up of the boiler. Depending upon circum-
stances, a protective coating may be required. See Section 3.9 in Chapter 3.
8.3 — Water Level Controls
The need to periodically check water level controls and the waterside of the pressure vessel cannot be
overemphasized. Most instances of major boiler damage 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. On steam boilers, the water column should be blown down daily. Check
samples of boiler water and condensate in accordance with procedures recommended by your local Cleaver-Brooks
authorized representative.
Since low water cutoff devices are generally set by the original manufacturer, no attempt should be made to adjust
these controls to alter the point of low water cutoff 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 previously established levels, contact your local Cleaver-
Brooks authorized representative.
8.3.1 — Steam Boiler
The CB Level Master (CB-LE high pressure steam boilers) facilitates preventive maintenance by providing a daily
reminder to the operator that a water column blowdown is required. A switch on the Level Master control panel
(optional external switch) allows blowdown to be performed while the boiler is running. Upon completion of the
procedure, the Level Master will indicate a successful blowdown and will time-stamp the event and record it in
controller memory.
The Level Master also has provisions to test the Auxiliary Low Water Cutoff (ALWCO). To perform the test, open
the bottom blowdown valves with the boiler running. When the water level reaches the ALWCO setpoint, the Level
Master will shut down the boiler. Restore water level and reset the Level Master controller to continue operation.
For complete information on the Level Master see CB manual #750-281.
CB-LE low pressure steam boilers utilize a snap switch type low water cutoff. In addition to a normal blowdown
routine, the head assembly should be removed and waterside components inspected annually. Ensure that the float
chamber and equalizing piping are free of sediment and debris.
8.3.2 — Hot Water Boiler
It is impractical to blow down 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 make-
up 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 verify proper operation. Remove the operating mechanism from the bowl annually or more
frequently, if possible, to check and clean float ball, internal moving parts, and the bowl housing. Also check the
cross-connecting piping to be certain that it is clean and free of obstruction.
To Next Page
Loading...
Need help?
General
