Check Operation And Safety Controls - Beckett CG25 Manual

Figure 14C. Manifold to Furnace Pressure Drop vs Rate CG50
6000
5000
4000
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ra
3000
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1000
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0.5 1 1.5 2 2.5 3
Pressure Drop, In. WC
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°CG50.2S
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Check operation and safety controls:
Testing by Qualified Tech-
nician Required.
Failure to properly test and verify the correct
function of operation and safety controls could
lead to equipment malfunction and result in as-
phyxiation, explosion or fire,
• The testing of operation and safety controls requires
technical training and experience with commercial
gas burning systems.
• Carefully follow the manufacturer's instructions sup-
plied with the controls.
• Verify the correct function of all operation and safety
controls used in the installation.
• If instructions are not available, use the following
recommended procedures and record all results in
a start-up log.
• Refer to Figure 7 for typical test points and compo-
nent locations.
.
High limit - To check the High Limit, raise the
temperature or pressure of the operating control to
a higher level and lower the limit to a setting less
than the operating control. Run the burner until the
high limit opens and shuts the burner off. Adjust the
controls back to the desired settings.
.
.
.
.
Operating control - Run the burner until the oper-
ating control shuts it off. If necessary, make adjust-
ments to ensure the control cycles the burner in the
desired temperature or pressure range.
Low water cutoff (LWCO) - With the burner firing,
open the blow down valve on the low water cutoff,
if applicable. As the water level drops, the LWCO
switch contacts open and shut the burner off. When
the water level rises, the LWCO contacts close and
restart the burner. Monitor the LWCO switch opera-
tion in relation to the water level in the sight-glass
for synchronization.
Airflow proving switch - With the burner firing at
its lowest rate, loosen the tubing connection to the
airflow proving switch. A loss in air pressure at the
tubing should immediately cause the diaphragm in
the switch to open and recycle or lockout the safe-
guard control.
Low gas pressure switch - With the burner firing
and a manometer attached to a test port near the
low pressure switch, gradually close the main leak
test cock to shut off the gas supply. Note the pres-
sure at which the low gas pressure switch opens
and shuts the burner off. Manually reset the switch.
The low gas pressure switch should be set at half
of the normal supply pressure in the line.
6104 BCGSO RoB 23