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Table 4 – Natural Gas Orifice Sizes and Manifold Pressure
208/230VAC Models
Nameplate
Input,
High Stage
(Btu/hr)
ALTITUDE OF INSTALLATION (FT. [m] ABOVE SEA LEVEL) U.S.A.*
0 to 2000
[0 to 610]
2001 to
3000*
[610 to
914]
3001 to
4000
[915 to
1219]
4001 to
5000
[1220 to
1524]
5001 to
6000
[1524 to
1829]
40000
Orifice No. (Qty) 44 (2) 45 (2)† 48 (2)† 48 (2)† 48 (2)†
Manifold Press. High / Low (in.
W.C.)
3.2 /1.4 3.2 /1.4 3.8 /1.6 3.5 /1.5 3.2 /1.4
60000
Orifice No. (Qty) 44 (3) 45 (3)† 48 (3)† 48 (3)† 48 (3)†
Manifold Press. High / Low (in.
W.C.)
3.2 /1.4 3.2 /1.4 3.8 /1.6 3.5 /1.5 3.2 /1.4
90000
Orifice No. (Qty) 38 (3) 41 (3)† 41 (3)† 42 (3)† 42 (3)†
Manifold Press. High / Low (in.
W.C.)
3.6 /1.6 3.8 /1.6 3.4 /1.5 3.4 /1.5 3.2 /1.4
115000
Orifice No. (Qty) 33 (3) 36 (3)† 36 (3)† 36 (3)† 38 (3)†
Manifold Press. High / Low (in.
W.C.)
3.8 /1.7 3.8 /1.7 3.6 /1.6 3.3 /1.4 3.6 /1.5
127000
Orifice No. (Qty) 31 (3) 31 (3) 33 (3)† 33 (3)† 34 (3)†
Manifold Press. High / Low (in.
W.C.)
3.7 /1.7 3.2 /1.4 3.5 /1.6 3.2 /1.4 3.2 /1.4
130000
Orifice No. (Qty) 31 (3) 31 (3) 33 (3)† 33 (3)† 34 (3)†
Manifold Press. High / Low (in.
.C.)
3.8 /1.7 3.2 /1.4 3.7 /1.6 3.4 /1.4 3.3 /1.4
Table 5 – Natural Gas Orifice Sizes and Manifold Pressure
460V
Nameplate
Input
(Btu/hr)
ALTITUDE OF INSTALLATION (FT. ABOVE SEA LEVEL) U.S.A.*
0 to 2000
( 0 --- 6 1 0
m)
2001 to
3000*
(611 to 914
m)
3001 to
4000
(915 to
1219 m)
4001 to
5000
(1220 to
1524 m)
5001 to
6000
(1524 to
1829 m)
60000
Orifice No. (Qty) 38 (2) 41 (2)† 41 (2)† 42 (2)† 42 (2)†
Manifold Press. (in. W.C.) 3.6 3.8 3.4 3.4 3.2
90000
Orifice No. (Qty) 38 (3) 41 (3)† 41 (3)† 42 (3)† 42 (3)†
Manifold Press. (in. W.C.) 3.6 3.8 3.4 3.4 3.2
115000
Orifice No. (Qty) 33 (3) 36 (3)† 36 (3)† 36 (3)† 38 (3)†
Manifold Press. (in. W.C.) 3.8 3.8 3.6 3.3 3.6
130000
Orifice No. (Qty) 31 (3) 31 (3) 33 (3)† 33 (3)† 34 (3)†
Manifold Press. (in. W.C.) 3.8 3.2 3.7 3.4 3.3
*In the U.S.A., the input rating for altitudes above 2000 ft (610m) must be reduced by 4% for each 1000 ft (305 m) above sea level.
In Canada, the input rating for altitudes from 2001 to 4500 ft (611 to 1372 m) above sea level must be derated by 10% by an authorized gas conversion station or
dealer.
For Canadian Installations from 2000 to 4500 ft, use U.S.A. column 2001 to 3000 ft (610 to 914 m).
† Orifices available through your distributor.
NOTE: Orifice sizes and manifold pressure settings are based on natural gas with a heating value of 1025 Btu/ft
3
and a specific gravity of .6.
577E