CleaverBrooks 4WI, Руководство по эксплуатации, обслуживанию и запасным частям

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Adjustment Procedures
6-8 750-211 (revised 2009)
Promethean Boilers, Model 4WI Manual
The high limit control provides a safety factor to shut the burner off in the event the operating limit control should
fail. The setting of the control should be sufficiently above the operating limit control to avoid nuisance shutdowns.
The setting, however, must be within the limits of the safety valve settings and should not exceed 90% of the valve
setting. The control requires manual resetting after it shuts off the burner.
In the setting of the controls, consideration must be given to the time required for a burner restart. Each start
requires a pre-purge period, plus the fixed time required for proving the pilot and main flame. In addition, approx-
imately one-half minute is required for the damper motor to travel from low- to high-fire. The time lag may allow
pressure or temperature to drop below desirable limits.
6.6 — Modulating Pressure Control: Steam
Turn the adjusting screw until the indicator is opposite the low point of
the desired modulating range. Modulated firing will range between the
low point and a higher point equal to the modulating range of the particu-
lar control. In 0-15 psi controls the range is 1/2 lb; in 5-150 psi controls
the range is 5 lbs; in 10-300 psi controls the range is 12 lbs.
FIGURE 6-7.
Modulating Pressure Control
6.7 — Operating Limit Pressure Control: Steam
Set the “cutout” (burner off) pressure on the main scale using the large adjusting screw. Set the differential on the
short scale by turning the small adjusting screw until the indicator points to the desired difference between cutout
and cut-in pressures. The “cut-in” (burner on) pressure is the cutout pressure minus the differential. The cutout
pressure should not exceed 90% of the safety valve setting.
To prevent burner shutdown at other than low-fire setting, adjust the modulating pressure control to modulate to low-
fire before the operating limit pressure control shuts off the burner. Failure to follow these instructions could result in
damage to the equipment.
!
Caution