Cleaver-Brooks CBH 40 - Water Gage Glass; Operating Controls

Chapter 5--Adjustment and Maintenance
WARNING
SAFE OPERATION OF YOUR GENERATOR DEMANDS PERIODIC
INSPECTION AND MAINTENANCE OF ALL LOW WATER CUT-
OFF DEVICES. OPEN AND INSPECT THEM AT LEAST ONCE A
MONTH. UNDER CONSTANT ATTENDANCE AND WITH BURN-
ER IN LOW FIRE POSITION, CHECK OPERATION FREQUENTLY
BY STOPPING WATER FLOW TO GENERATOR, AND ALLOW1NG
WATER LEVEL TO LOWER. IF CONTROLS DO NOT CUT OFF
BURNER AT PROPER SAFE WATER LEVEL OR APPEAR IN
-::
POOR PHYSICAL CONDITION. REPAIR OR REPLACE AT ONCE.
• •
FIGURE 5-l. LOW WATER PLATE
On a steam boiler, the head mechanism of the low
water cut-off device(s) should be removed from the
bowl at least once a month to check and clean the
float ball, the internal moving parts, and the bowl
or
water column.
Remove the pipe plugs from the tees or crosses and
make certain the cross connecting piping is clean
and free of obstructions. Controls must be mounted
in a plumb position for proper performance. Deter-
mine that piping is vertically aligned after ship-
ment and installation and throughout life of equip-
ment.
A scheduled blowdown of the water controls on a
steam boiler should be maintained.
It is impractical to blowdown the low water cut-off
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 arrange-
ment usually makes it impractical to perform daily
and monthly maintenance of the low water cut-off
devices,
it is essential to remove the operating
mechanism from the bowl annually or more fre-
quently, if possible, to check and clean 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.
D. WATER GAGE GLASS
A broken or discolored glass should be replaced at
once. Periodic replacement should be a part of the
maintenance program. Always use new gaskets
when replacing a glass. Use a proper size rubber
packing. Do not use "loose packing" which could
be forced below the glass and possibly plug the
valve opening.
Close
the valves when replacing the glass. Slip a
packing nut, a packing washer, and packing ring
onto each end of the glass. Insert one end of the
glass into the upper gage valve body far enough to
allow the lower end to be dropped into the lower
body.
Slide the packing nuts onto each valve and
tighten.
If the glass is replaced while the boiler is in ser-
vice, open the blowdown and slowly bring the glass
to operating temperature by cracking the gage
valves slightly. After glass is warmed up, close the
blowdown valve and open the gage valves com-
pletely.
Check try-cocks
and gage cocks for freedom of
operation and clean as required. It is imperative
that the gage cocks are mounted in exact align-
ment. If they are not, the glass will be strained and
may fail prematurely.
E. OPERATING CONTROLS
In general when adjusting controls check to see
that they are level, especially those containing
mercury switches. On temperature sensing controls
make sure that the bulb is properly bottomed in its
well.
Make sure that connecting tubing is not
kinked or damaged.
Controls are carefully calibrated during their
manufacture and do not normally require re-cali-
bration. The dial settings are generally quite ac-
curate although it is not unusual to have a slight
variation between a scale setting and an actual
pressure gauge or thermometer reading and to re-
adjust control setting to agree with these readings.
This is predicated, however, on pressure gauges
and thermometers being accurate.
Most of the operating controls require very little
maintenance beyond occasional inspection.
Examine tightness of electrical connections. Keep