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3.7
Firing rates
The burners can work in two ways: low and high fire.
MAXIMUM OUTPUT must be selected in area A.
MINIMUM OUTPUT must not be lower than the minimum limit
shown in the diagram:
Model
RLS 28/M
RLS 38/M
RLS 50/M
The firing rate area values have been obtained con-
sidering an ambient temperature of 68 °F, and an
atmospheric pressure of 394" WC and with the
WARNING
combustion head adjusted as shown on page 27.
NOTE:
The firing rate areas given in Fig. 3 have been reduced by 10% with
respect to the maximum range that can be reached.
Consult procedure to refer burner operating condition in high alti-
tude plants.
3.7.1
Burner firing rates according to air density
Find the CORRECTED BURNER CAPACITY for the plant's alti-
tude in chart 1 and the CORRECTED PRESSURE in chart 2.
Check in the firing rate graph of the burner Fig. 3, if the working
point defined by the values above is within the range limits.
If not, higher burner size is needed.
Note
➤ Charts are based only on altitude variation (reference temper-
ature = 68 °F, 20 °C)
➤ To get the combined correction in case of different air temper-
ature, a compensation of 1000 ft each 20 °F (305 m each 11
°C) is applicable (100 ft = 2°F).
Example
Rated capacity = 1500 MBtu/hr - Rated air pressure = 1.5" WC
Real altitude
= 3000 ft - Real temperature = 88 °F
∆
= 88 °F - 68 °F (reference temp.) = 20 °F
(equivalent 1000 ft variation)
20 : 2 = 10 x 100 = 1000 ft
Proceeding as descripted above and considering a "virtual altitude"
of (3000 + 1000) ft:
–
1500 MBtu/hr at 4000 ft, the corrected capacity is 1713 MBtu/hr
–
1.5" WC at 4000 ft, the corrected burner air pressure is 1.71
Reference conditions:
–
Ambient temperature 68 °F (20 °C)
–
Barometric pressure 394" WC (1000 mbar)
Altitude 328 ft a.s.l. (100 m a.s.l.).
Technical description of the burner
MBtu/hr
GPH
378
2.7
434
3.1
546
3.9
RLS 28/M
RLS 38/M
RLS 50/M
9
GB
D2537
Fig. 3
20019893
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