Table 8—Model 58RAV Orifice Size† and Manifold Pressure for Correct Input
(Tabulated Data Based on 23,000 BTUH Per Burner, Derated 4 Percent per 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.
and
Canada
850
41
3.6
41
3.7
41
3.8
40
3.6
40
3.8
875
42
3.8
41
3.5
41
3.6
41
3.7
41
3.8
900
42
3.5
42
3.7
42
3.8
41
3.5
41
3.6
0
925
42
3.4
42
3.5
42
3.6
42
3.7
42
3.8
950
42
3.2
42
3.3
42
3.4
42
3.5
42
3.6
to
975
43
3.7
43
3.8
42
3.2
42
3.3
42
3.4
1000
43
3.5
43
3.6
43
3.7
42
3.2
42
3.3
2000
1025
43
3.3
43
3.4
43
3.6
43
3.7
43
3.8
1050
43
3.2
43
3.3
43
3.4
43
3.5
43
3.6
1075
44
3.5
44
3.6
43
3.2
43
3.3
43
3.4
1100
44
3.3
44
3.4
44
3.5
43
3.2
43
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.
and
Canada
U.S.A
775
42
3.7
42
3.8
41
3.5
41
3.6
41
3.8
Altitudes
800
42
3.4
42
3.6
42
3.7
42
3.8
41
3.5
2001
825
42
3.2
42
3.3
42
3.5
42
3.6
42
3.7
to
850
43
3.7
43
3.8
42
3.3
42
3.4
42
3.5
3000
875
43
3.5
43
3.6
43
3.7
42
3.2
42
3.3
or
900
43
3.3
43
3.4
43
3.5
43
3.7
43
3.8
Canada
925
43
3.1
43
3.2
43
3.4
43
3.5
43
3.6
Altitudes
950
43
3.0
43
3.1
43
3.2
43
3.3
43
3.4
2000
975
43
2.8
43
2.9
43
3.0
43
3.1
43
3.2
to
1000
43
2.7
43
2.8
43
2.9
43
3.0
43
3.1
4500
1025
43
2.6
43
2.6
43
2.7
43
2.8
43
2.9
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
750
42
3.4
42
3.6
42
3.7
42
3.8
41
3.5
775
42
3.2
42
3.3
42
3.5
42
3.6
42
3.7
800
43
3.7
43
3.8
42
3.2
42
3.3
42
3.4
3001
825
43
3.5
43
3.6
43
3.7
43
3.8
42
3.2
850
43
3.3
43
3.4
43
3.5
43
3.6
43
3.7
to
875
43
3.1
43
3.2
43
3.3
43
3.4
43
3.5
900
43
2.9
43
3.0
43
3.1
43
3.2
43
3.3
4000
925
43
2.8
43
2.9
43
3.0
43
3.0
43
3.1
950
43
2.6
43
2.7
43
2.8
43
2.9
43
3.0
975
43
2.5
43
2.6
43
2.7
43
2.7
43
2.8
1000
43
2.4
43
2.4
43
2.5
43
2.6
43
2.7
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
42
3.2
42
3.3
42
3.5
42
3.6
42
3.7
750
43
3.7
43
3.8
42
3.2
42
3.3
42
3.4
775
43
3.4
43
3.6
43
3.7
43
3.8
42
3.2
4001
800
43
3.2
43
3.3
43
3.5
43
3.6
43
3.7
825
43
3.0
43
3.1
43
3.2
43
3.4
43
3.5
to
850
43
2.9
43
3.0
43
3.1
43
3.2
43
3.3
875
43
2.7
43
2.8
43
2.9
43
3.0
43
3.1
5000
900
43
2.6
43
2.6
43
2.7
43
2.8
43
2.9
925
43
2.4
43
2.5
43
2.6
43
2.7
43
2.8
950
43
2.3
43
2.4
43
2.5
43
2.5
43
2.6
* For size 135-20 only, input is 22,500 Btuh per burner. Deduct 0.1-in. wc from manifold pressure shown in table. Change orifice size if manifold pressure falls below
3.2-in. wc on altitudes up to 2000 ft, otherwise change orifice size if manifold pressure falls below 2.0-in. wc.
† Orifice sizes shown in BOLD are factory installed.
16