CleaverBrooks FLX Operation, Service And Parts Manual page 9

GENERAL DESCRIPTION
3. Modulating Limit Pressure Control (Figure 1-2 and 1-3):
Senses changing boiler pressures and transmits the
information to the modulating motor to change the
burner firing rate when the manual-automatic switch is
set on "automatic."
4. Low Water Cutoff and Pump Control (Figure 1-2, 1-4
and 1-5): Float-operated control responds to the water
level in the boiler. It performs two distinct functions:
•Stops firing of the burner if water level lowers below the
safe operating point. Energizes the low-water light in the
control panel; also causes low-water alarm bell (optional
equipment) to ring. Code requirements of some models
require a manual reset type of low-water cutoff.
•Starts and stops the feedwater pump (if used) to maintain
water at the proper operating level.
! DANGER
Determine that the main and auxiliary low
water cutoffs and pump control are level af-
ter installation and throughout the equip-
ment's operating life. Failure to follow these
instructions could result in equipment dam-
age.
WATER COLUMN
LOW WATER CUTOFF
AND PUMP CONTROL
GAUGE GLASS
DRAIN VALVE
WATER COLUMN
DRAIN VALVE
CONTROL PANEL
FLAME
DETECTOR
FORCED DRAFT
FAN MOTOR MODULATING
750-177
CAUTION
HIGH LIMIT OPERATING LIMIT
PRESSURE PRESSURE
CONTROL CONTROL
MOTOR
OIL SUPPLY
PRESSURE
GAUGE
OIL SOLENOID
VALVES
Figure 1-2: Typical Steam Boiler - Light Oil Fired
5. Water Column Assembly (Figure 1-2): Houses the low-
water cutoff and pump control and includes the water
gauge glass, gauge glass shutoff cocks.
6. Water Column Drain Valve (Figure 1-2): Provided so
that the water column and its piping can be flushed
regularly to assist in maintaining cross-connecting
piping and in keeping the float bowl clean and free of
sediment. A similar drain valve is furnished with
auxiliary low-water cutoff for the same purpose.
7. Gauge Glass Drain Valve (Figure 1-2): Provided to flush
the gauge glass.
8. Safety Valve(s) (Figure 1-6 and 1-8): Prevent buildup
over the design pressure of the pressure vessel. The size,
rating and number of valves on a boiler is determined by
the ASME Boiler Code. The safety valves and the
discharge piping are to be installed to conform to the
ASME code requirements. The installation of a valve is
of primary importance to its service life. A valve must be
mounted in a vertical position so that discharge piping
and code-required drains can be properly piped to
prevent buildup of back pressure and accumulation of
foreign material around the valve seat area. Apply only a
moderate amount of pipe compound to male threads and
MODULATING LIMIT
PRESSURE
CONTROL
STEAM PRESSURE
GAUGE
OIL PUMP
Chapter 1
1-3