Preparations for Startup
3-12
750-392
CBEX-DE
This is the CFH (at line pressure) that must pass through the meter so that the equivalent full input requirement
of 25,100 CFH (at base pressure) will be delivered.
3.8.4 — Checking Gas Flow
Your gas supplier can generally furnish a gas meter flow chart from which gas flow can be determined. After a
short observation period, the information aids in adjusting the regulator to increase or decrease flow as required
to obtain the rating.
The information given in this section is for all practical purposes sufficient to set and adjust controls for gas
input. Your gas supplier can, if necessary, furnish exact correction factors that take into consideration Btu con-
tent, exact base pressure, specific gravity, temperature, etc., of the gas used.
3.9 — Adjusting Combustion
3.10 — Linkage Settings (optional single-point systems)
The linkage consists of various arms, connecting rods, and swivel ball joints that transmit motion form the mod-
ulating motor to the metering cam(s), rotary air damper, and gas butterfly valve.
When properly adjusted, a coordinated movement of the damper and metering cams within the limits of the
modulating motor travel is attained to provide proper fuel-air ratios through the firing range.
In linkage adjustments there are several important factors that must serve as guides.
• The modulating motor must be able to complete its full travel range.
Combustion settings are made using the Hawk control system. Refer to manual included with the boiler controls.
BTU/hr input
BTU/cu ft
= CFH (cubic feet/hour)
= 21,271 CFH
= 25,100 CFH (at 14.7 lb atmospheric base pressure)
or
25,100,000
1,000
then
25,100
1.18
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