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