TABLE 7—MODEL 376CAV ORIFICE SIZE† AND MANIFOLD PRESSURE FOR CORRECT INPUT
(TABULATED DATA BASED ON 23,000 BTUH PER BURNER, DERATED 4 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.
and
Canada
0
to
2000
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
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
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
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
(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.
Altitudes
2001
to
3000
or
Canada
Altitudes
2000
to
4500
775
42
3.7
42
3.8
41
3.5
41
3.6
41
3.8
800
42
3.4
42
3.6
42
3.7
42
3.8
41
3.5
825
42
3.2
42
3.3
42
3.5
42
3.6
42
3.7
850
43
3.7
43
3.8
42
3.3
42
3.4
42
3.5
875
43
3.5
43
3.6
43
3.7
42
3.2
42
3.3
900
43
3.3
43
3.4
43
3.5
43
3.7
43
3.8
925
43
3.1
43
3.2
43
3.4
43
3.5
43
3.6
950
43
3.0
43
3.1
43
3.2
43
3.3
43
3.4
975
43
2.8
43
2.9
43
3.0
43
3.1
43
3.2
1000
43
2.7
43
2.8
43
2.9
43
3.0
43
3.1
1025
43
2.6
43
2.6
43
2.7
43
2.8
43
2.9
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
3001
to
4000
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
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
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
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
(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
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
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
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
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 060135 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 SHADING are factory installed.
—16—
