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Table 14—Model 58MTB Orifice Size and High/Low-Heat Manifold Pressures for Correct Inputs (Continued)
for Use With 060 Through 120 Size Furnaces Only
(Tabulated Data Based on 20,000/13,000 Btuh per Burner,
Derated 2 Percent for Each 1000 ft Above Sea Level)*
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
(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
4001
to
5000
9%
derate
725
43
3.7/1.5
43
3.8/1.6
42
3.2/1.4
42
3.3/1.4
42
3.4/1.4
750
44
3.4/1.4
43
3.5/1.5
43
3.7/1.5
43
3.8/1.6
42
3.2/1.4
775
44
3.7/1.6
44
3.8/1.6
43
3.4/1.4
43
3.5/1.5
43
3.7/1.5
800
44
3.51.5
44
3.6/1.5
44
3.7/1.6
44
3.8/1.6
43
3.4/1.4
825
44
3.2/1.4
44
3.4/1.4
44
3.5/1.5
44
3.6/1.5
44
3.7/1.6
850
45
3.5/1.5
45
3.8/1.6
44
3.3/1.4
44
3.4/1.4
44
3.5/1.5
875
45
3.3/1.4
45
3.6/1.5
45
3.7/1.6
44
3.2/1.3
44
3.3/1.4
900
45
3.3/1.4
45
3.4/1.4
45
3.5/1.5
45
3.6/1.5
45
3.8/1.6
925
47
3.7/1.6
45
3.2/1.4
45
3.3/1.4
45
3.4/1.5
45
3.6/1.5
950
47
3.5/1.5
47
3.6/1.5
45
3.2/1.3
45
3.3/1.4
45
3.4/1.4
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
(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
5001
to
6000
11%
derate
700
43
3.6/1.5
43
3.7/1.6
42
3.2/1.3
42
3.3/1.4
42
3.4/1.4
725
43
3.4/1.4
43
3.5/1.5
43
3.6/1.5
43
3.7/1.6
43
3.8/1.6
750
44
3.6/1.5
44
3.7/1.6
43
3.4/1.4
43
3.5/1.5
43
3.6/1.5
775
44
3.4/1.4
44
3.5/1.5
44
3.6/1.5
44
3.7/1.6
43
3.4/1.4
800
44
3.2/1.3
44
3.3/1.5
44
3.4/1.4
44
3.5/1.5
44
3.6/1.5
825
45
3.6/1.5
45
3.7/1.6
44
3.2/1.4
44
3.3/1.4
44
3.4/1.4
850
45
3.4/1.4
45
3.5/1.5
45
3.6/1.5
45
3.8/1.6
44
3.2/1.4
875
45
3.2/1.4
45
3.3/1.4
45
3.4/1.5
45
3.6/1.5
45
3.7/1.5
900
47
3.6/1.5
47
3.7/1.6
45
3.3/1.4
45
3.4/1.4
45
3.5/1.5
925
47
3.4/1.4
47
3.5/1.5
47
3.7/1.5
45
3.2/1.3
45
3.3/1.4
950
48
3.7/1.6
48
3.8/1.6
47
3.5/1.5
47
3.6/1.5
47
3.7/1.6
975
48
3.5/1.5
48
3.6/1.5
48
3.8/1.6
47
3.4/1.4
47
3.5/1.5
1000
48
3.3/1.4
48
3.5/1.5
48
3.6/1.5
48
3.7/1.6
48
3.8/1.6
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
(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
6001
to
7000
13%
derate
650
42
3.2/1.3
42
3.3/1.4
42
3.4/1.4
42
3.5/1.5
42
3.6/1.6
675
43
3.6/1.5
43
3.7/1.6
43
3.8/1.6
42
3.2/1.4
42
3.3/1.4
700
44
3.8/1.6
43
3.4/1.5
43
3.6/1.5
43
3.7/1.6
43
3.8/1.6
725
44
3.6/1.5
44
3.7/1.6
44
3.8/1.6
43
3.4/1.4
43
3.5/1.5
750
44
3.3/1.4
44
3.4/1.5
44
3.6/1.5
44
3.7/1.6
44
3.8/1.6
775
45
3.8/1.6
44
3.2/1.4
44
3.3/1.4
44
3.4/1.5
44
3.5/1.5
800
45
3.5/1.5
45
3.7/1.5
45
3.8/1.6
44
3.2/1.4
44
3.3/1.4
825
45
3.3/1.4
45
3.4/1.5
45
3.6/1.5
45
3.7/1.6
45
3.8/1.6
850
47
3.7/1.6
45
3.2/1.4
45
3.4/1.4
45
3.5/1.5
45
3.6/1.5
875
47
3.5/1.5
47
3.6/1.5
45
3.2/1.3
45
3.3/1.4
45
3.4/1.4
* Orifice numbers shown in shading are factory installed.
NOTE: Percents of derate are based on midpoints of U.S. altitude ranges.
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