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5. MAINTENANCE OF LOW WATER CUTOFF
DEVICES
Probe and float type low water cutoff devices require annual
inspection and maintenance.
Les interrupteurs à bas niveau d’eau de type sonde ou
de type flotteur doivent être inspectés et entretenus
annuellement.
A. Probe Type Low Water Cut Off
Although these
devices are solid state in design, the probe is
exposed to possible contamination in the boiler
water.
It is important to physically remove the probe
from the boiler tapping annually and inspect it for
accumulation of scale or sediment.
Following these steps inspect, clean and/or
replace the probe:
1. Turn off electric service to the boiler.
2. Drain boiler water to a level below the tapping
for the probe.
3. Disconnect the wiring connections between
the low water cutoff and the probe.
4. Dismount the low water cutoff control from the
probe.
5. Unscrew the probe from the boiler tapping.
6. Inspect that portion of the probe that is
exposed to the boiler water for scale or
sediment buildup.
7. Light deposits may be removed by wiping the
probe with a damp cloth. Wiping the probe
with a cloth soaked in vinegar will remove
more tenacious lime deposits. The most
stubborn deposits may be removed from the
probe by using diluted amount (3 part of water
to 1 part) of phosphoric acid (H2PO4).
Clean firetubes with flue brush and reinstall
turbulators. If turbulators are corroded or
deteriorated, replacing them will ensure a high
level of boiler efficiency. Remove soot and rust
and reseal the boiler.
Turbulator quantities are shown below. Access to
turbulator replacement is from the front smokebox.
Turbulators should be installed and removed from
the front of the boiler only.
Series 4FH: All 4FH Series boilers come equipped
with turbulators in all third pass tubes (upper rows
of tubes), with quantities as follows:
1. Sizes 63A/107A quantity of (18).
2. Sizes 127A/209A quantity of (22).
3. Sizes 240A/345A quantity of (40).
4. Sizes 360A/450A quantity of (46).
5. Sizes 563A/675A quantity of (56).
6. Sizes 827/993 quantity of (54).
7. Sizes 1157/1323 quantity of (72).
8. Size 1654 quantity of (93).
9. Size 1985/2315 quantity of (109).
10. Size 2645 quantity of 113.
11. Size 3075A quantity of (151).
4. BOTTOM BLOWDOWN PROCEDURE
Burnham high pressure steam boilers are equipped
with two bottom blowdown connections. Bottom
blowdown should be done while the boilers are under
pressure, with the burner off or at low fire. There should
be two quick-opening valves and one downstream
slow-opening valve. Open the slow-opening valve first.
Slowly open the front quick-opening valve to warm up
the piping and blowdown separator. Open the valve for
a few seconds with a quick blast to flush out sludge and
sediment from the bottom of the boiler. Do not lower the
boiler water level by more than ½
"
. Close the valve, then
repeat for the rear quick-opening valve. Close the slow-
opening valve. Make sure all valves are closed. A water
treatment consultant can recommend an appropriate
manual blowdown schedule, but is generally done once
per shift.
Water columns should be blown down once per shift to
keep the internal parts of the pump control and low water
cutoff free from sediment. If the boiler is equipped with a
“water column bypass” switch, depress the switch while
performing the blowdown. Close the valve and release
the switch.
