Table 9—Model 58MSA Orifice Size and Manifold Pressure for Correct Input
Continued
(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
725
43
3.7
43
3.8
42
3.2
42
3.3
42
3.4
750
43
3.4
43
3.5
43
3.7
43
3.8
42
3.2
775
44
3.7
44
3.8
43
3.4
43
3.5
43
3.7
4001
800
44
3.5
44
3.6
44
3.7
44
3.8
43
3.4
825
44
3.2
44
3.4
44
3.5
44
3.6
44
3.7
to
850
45
3.7
45
3.8
44
3.3
44
3.4
44
3.5
875
45
3.5
45
3.6
45
3.7
44
3.2
44
3.3
5000
900
45
3.3
45
3.4
45
3.5
45
3.6
45
3.8
9%
925
45
3.1
45
3.2
45
3.3
45
3.4
45
3.6
derate
950
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
700
43
3.6
43
3.7
42
3.2
42
3.3
42
3.4
725
43
3.4
43
3.5
43
3.6
43
3.7
43
3.8
750
44
3.6
44
3.7
43
3.4
43
3.5
43
3.6
775
44
3.4
44
3.5
44
3.6
44
3.7
43
3.4
5001
800
44
3.2
44
3.3
44
3.4
44
3.5
44
3.6
825
45
3.6
45
3.7
44
3.2
44
3.3
44
3.4
to
850
45
3.4
45
3.5
45
3.6
45
3.8
44
3.2
875
45
3.2
45
3.3
45
3.4
45
3.6
45
3.7
6000
900
45
3.0
45
3.1
45
3.3
45
3.4
45
3.5
925
45
2.9
45
3.0
45
3.1
45
3.2
45
3.3
11%
950
45
2.7
45
2.8
45
2.9
45
3.0
45
3.1
derate
975
45
2.6
45
2.7
45
2.8
45
2.9
45
2.9
1000
45
2.5
45
2.5
45
2.6
45
2.7
45
2.8
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
650
42
3.2
42
3.3
42
3.4
42
3.5
42
3.6
675
43
3.6
43
3.7
43
3.8
42
3.2
42
3.3
700
44
3.8
43
3.4
43
3.6
43
3.7
43
3.8
6001
725
44
3.6
44
3.7
44
3.8
43
3.4
43
3.5
750
44
3.3
44
3.4
44
3.6
44
3.7
44
3.8
to
775
45
3.8
44
3.2
44
3.3
44
3.4
44
3.5
800
45
3.5
45
3.7
45
3.8
44
3.2
44
3.3
7000
825
45
3.3
45
3.4
45
3.6
45
3.7
45
3.8
13%
850
45
3.1
45
3.2
45
3.4
45
3.5
45
3.6
derate
875
45
3.0
45
3.1
45
3.2
45
3.3
45
3.4
*Orifice numbers 45 are factory installed.
Percents of derate are based on midpoints of U.S. altitude ranges.
39