![background image](http://html.mh-extra.com/html/carrier/58mxb-series/58mxb-series_installation-start-up-and-operating-instructions-manual_2562825050.webp)
Table 13—Model 58MXB Orifice Size and Manifold Pressure for Correct Input
(Continued)
For Use with 040 through 120 Size Furnaces Only
(Tabulated Data Based on 20,000 Btuh per Burner, Derated 2% for Each 1000 Ft Above Sea Level) *
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
AT ALTITUDE
(BTU/CU FT)
SPECIFIC GRAVITY OF NATURAL GAS
0.58
0.60
0.62
0.64
0.66
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
U.S.A.
Only
625
43
3.8
42
3.3
42
3.4
42
3.5
42
3.6
650
43
3.5
43
3.7
43
3.8
42
3.2
42
3.3
675
44
3.8
43
3.4
43
3.5
43
3.6
43
3.7
7001
700
44
3.5
44
3.6
44
3.8
43
3.4
43
3.5
725
44
3.3
44
3.4
44
3.5
44
3.6
44
3.7
to
750
45
3.7
45
3.8
44
3.3
44
3.4
44
3.5
775
45
3.5
45
3.6
45
3.7
45
3.8
44
3.3
8000
800
45
3.3
45
3.4
45
3.5
45
3.6
45
3.7
15%
825
45
3.1
45
3.2
45
3.3
45
3.4
45
3.5
derate
850
45
2.9
45
3.0
45
3.1
45
3.2
45
3.3
ALTITUDE
RANGE
(Ft)
Avg GAS
HEAT VALUE
AT ALTITUDE
(Btu/cu ft)
SPECIFIC GRAVITY OF NATURAL GAS
0.58
0.60
0.62
0.64
0.66
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
U.S.A.
Only
600
43
3.8
42
3.3
42
3.4
42
3.5
42
3.6
625
43
3.5
43
3.6
43
3.8
42
3.2
42
3.3
8001
650
44
3.7
43
3.4
43
3.5
43
3.6
43
3.7
675
44
3.5
44
3.6
44
3.7
44
3.8
43
3.4
to
700
44
3.2
44
3.3
44
3.4
44
3.6
44
3.7
725
45
3.6
45
3.8
44
3.2
44
3.3
44
3.4
9000
750
45
3.4
45
3.5
45
3.6
45
3.8
44
3.2
17%
775
45
3.2
45
3.3
45
3.4
45
3.5
45
3.6
derate
800
45
3.0
45
3.1
45
3.2
45
3.3
45
3.4
ALTITUDE
RANGE
(ft)
Avg GAS
HEAT VALUE
AT ALTITUDE
(Btu/cu ft)
SPECIFIC GRAVITY OF NATURAL GAS
0.58
0.60
0.62
0.64
0.66
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
U.S.A.
Only
575
43
3.8
42
3.2
42
3.3
42
3.5
42
3.6
600
43
3.5
43
3.6
43
3.7
42
3.2
42
3.3
9001
625
44
3.7
44
3.8
43
3.5
43
3.6
43
3.7
650
44
3.4
44
3.5
44
3.7
44
3.8
43
3.4
to
675
45
3.8
44
3.3
44
3.4
44
3.5
44
3.6
700
45
3.6
45
3.7
45
3.8
44
3.3
44
3.4
10,000
725
45
3.3
45
3.4
45
3.6
45
3.7
45
3.8
19%
750
45
3.1
45
3.2
45
3.3
45
3.4
45
3.5
derate
775
45
2.9
45
3.0
45
3.1
45
3.2
45
3.3
Orifice numbers 45 shown in BOLD are factory installed.
Percents of derate are based on midpoints of U.S. altitude ranges.
50