Low Pressure Orifice Chart
The information contained in this chart is meant to be general in nature. There are many factors which go into compiling a specific number of Btu's per cubic foot, such as gas temperature, altitude, and source of gas {like Kentucky, New York, etc.}, factors which can all vary. So these numbers are close to the fact, but not exactly 100% accurate.
Low Pressure Chart
GAS USE IN BTUS PER HOUR AGAINST A GIVEN
ORIFICE SIZE (DRILL SIZE) |
| DRILL SIZE |
Decimal Equivalent |
Natural Gas |
Natural Gas |
LP Gas |
| ↓ |
Gas Pressure→ |
4" WC |
7"WC |
11" WC |
| |
|
Gas use in Btus/hr |
Gas use in Btus/hr |
Gas use in Btus/hr |
| 75 |
0.021 |
1200 |
1600 |
3080 |
| 70 |
0.028 |
2125 |
2825 |
5475 |
| 65 |
0.035 |
2240 |
4400 |
8560 |
| 60 |
0.040 |
4350 |
5750 |
11175 |
| 3/64" |
0.047 |
5975 |
7900 |
15360 |
| 55 |
0.052 |
7350 |
9710 |
18890 |
| 50 |
0.070 |
13300 |
17590 |
34250 |
| 45 |
0.082 |
18250 |
24150 |
46975 |
| 3/32" |
0.094 |
23875 |
31600 |
61460 |
| 40 |
0.098 |
26075 |
34500 |
67095 |
| 7/64" |
0.109 |
32490 |
42980 |
83600 |
| 35 |
0.110 |
32850 |
43450 |
84525 |
| 1/8" |
0.125 |
42415 |
56100 |
109150 |
| 30 |
0.129 |
44820 |
59300 |
115345 |
| 9/64" |
0.141 |
53660 |
71000 |
138090 |
| 25 |
0.150 |
60670 |
80260 |
156150 |
| 5/32" |
0.156 |
66310 |
87725 |
170650 |
| 20 |
0.161 |
70360 |
93075 |
181075 |
| 11/64" |
0.172 |
80200 |
106100 |
206425 |
| 15 |
0.180 |
87950 |
116350 |
226350 |
| 3/16" |
0.188 |
95430 |
126250 |
245575 |
| 10 |
0.194 |
101630 |
134450 |
261575 |
| 13/64" |
0.203 |
111950 |
148100 |
288000 |
| 5 |
0.206 |
114640 |
151640 |
295000 |
| 7/32" |
0.219 |
129940 |
171900 |
334450 |
| 1 |
0.228 |
141110 |
186675 |
363150 |
|
Pressure Equivalency Chart
| INCHES OF WATER |
POUNDS PER SQUARE INCH |
| 4 |
0.1445 |
| 7 |
0.2529 |
| 11 |
0.3974 |