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
7001
to
8000
15%
derate
625
43
3.8/1.6
42
3.3/1.4
42
3.4/1.4
42
3.5/1.5
42
3.6/1.5
650
43
3.5/1.5
43
3.7/1.6
43
3.8/1.6
42
3.2/1.4
42
3.3/1.4
675
44
3.8/1.6
43
3.4/1.4
43
3.5/1.5
43
3.6/1.5
43
3.7/1.6
700
44
3.5/1.5
44
3.6/1.5
44
3.8/1.6
43
3.4/1.4
43
3.5/1.5
725
44
3.3/1.4
44
3.4/1.4
44
3.5/1.5
44
3.6/1.5
44
3.7/1.6
750
45
3.7/1.6
45
3.8/1.6
44
3.3/1.4
44
3.4/1.4
44
3.5/1.5
775
45
3.5/1.5
45
3.6/1.5
45
3.7/1.6
45
3.8/1.6
44
3.3/1.4
800
45
3.3/1.4
45
3.4/1.4
45
3.5/1.5
45
3.6/1.5
45
3.7/1.6
825
47
3.6/1.5
45
3.2/1.3
45
3.3/1.4
45
3.4/1.4
45
3.5/1.5
850
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
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
Altitudes
8001
to
9000
17%
derate
600
43
3.8/1.6
42
3.3/1.4
42
3.4/1.4
42
3.5/1.5
42
3.6/1.5
625
43
3.5/1.5
43
3.6/1.5
43
3.8/1.6
42
3.2/1.4
42
3.3/1.4
650
44
3.7/1.6
43
3.4/1.4
43
3.5/1.5
43
3.6/1.5
43
3.7/1.6
675
44
3.5/1.5
44
3.6/1.5
44
3.7/1.6
44
3.8/1.6
43
3.4/1.5
700
44
3.2/1.4
44
3.3/1.4
44
3.4/1.5
44
3.6/1.5
44
3.7/1.6
725
45
3.6/1.5
45
3.8/1.6
44
3.2/1.4
44
3.3/1.4
44
3.4/1.4
750
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
775
45
3.2/1.3
45
3.3/1.4
45
3.4/1.4
45
3.5/1.5
45
3.6/1.5
800
47
3.6/1.5
47
3.7/1.6
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
9001
to
10,000
19%
derate
575
43
3.8/1.6
42
3.2/1.4
42
3.3/1.4
42
3.3/1.5
42
3.6/1.5
600
43
3.5/1.5
43
3.6/1.5
43
3.7/1.6
42
3.2/1.3
42
3.3/1.4
625
44
3.7/1.6
44
3.8/1.6
43
3.5/1.5
43
3.6/1.5
43
3.7/1.6
650
44
3.4/1.4
44
3.5/1.5
44
3.7/1.5
44
3.8/1.6
43
3.4/1.4
675
44
3.8/1.6
44
3.3/1.4
44
3.4/1.4
44
3.5/1.5
44
3.6/1.5
700
45
3.6/1.5
45
3.7/1.6
45
3.8/1.6
44
3.3/1.4
44
3.4/1.4
725
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
750
47
3.7/1.6
45
3.2/1.4
45
3.3/1.4
45
3.4/1.5
45
3.5/1.5
775
47
3.5/1.5
47
3.6/1.5
47
3.7/1.6
45
3.2/1.4
45
3.3/1.4
*Orifice numbers shown in shading are factory installed.
NOTE: Percents of derate are based on midpoints of U.S. altitude ranges.
54