Checking Gas Rates and Heat Inputs – Natural Gas
November 3, 2009 by carl
CHECKING GAS RATES AND HEAT INPUTS (M3)
NATURAL GAS
Where the gas meter records the gas consumption in cubic metres the following procedure should be used.
Gas Rate Procedure Meter Measuring in m3
The following procedure is just one method of calculating gas rate: -
- Turn all the appliances OFF.
- Record the meter reading. (example shows a reading of 00048.104m3)
- Turn the appliance under test to FULL ON.
- At the same time as turning the appliance on start recording the time
- When exactly two minutes have elapsed record the meter reading. (example shows a reading of 00048.188m3)
- Subtract the first reading from the second reading. This will give you the volume of gas passed in m3.
Gas rate over two minutes: -
| = | 48.188 |
| -48.104 | |
| = | 00.084 m3 |
Therefore the Gas Rate over 1 minute
| = | 00.084 m3 ÷ 2 |
| = | 0.042m3 |
So to calculate the hourly consumption, the gas rate for 1 minute is multiplied by the number of minutes in an hour.
Therefore Gas Rate/hour
| = | 0.042 x 60 |
| = | 2.52m3/hr |
We can convert this figure to cubic feet by multiplying the figure by 35.37.
Therefore 2.52 x 35.37 = 89.1324ft3/hr
Gross Heat Input = 89.1324 x 1040 = 92697 Btu/hr (27.16 KW)
To assist in the process, the chart below has been configured to provide an easy reference. It is based on a GROSS CV of 38.79MJ/m3 (1040 Btu/ft3). So in our example over a two minute period 0.084m3 is used, look at the table below for 0.080 = 2.40 m3/hr (25.8KW) and 0.004 = 0.12m3/hr (1.3KW). Add the two together 2.40 + 0.12 = 2.52m3/hr and a gross input of
25.8 + 1.3 = 27.1KW
|
GAS USED in 2 Minutes |
HOURLY RATE EQUIVALENT |
EQUIVALENT HEAT INPUT |
||
|
M3 |
M3 |
Ft3 |
kW |
Btu/hr |
|
0.001 |
0.03 |
1.06 |
0.3 |
1100 |
|
0.002 |
0.06 |
2.12 |
0.6 |
2200 |
|
0.003 |
0.09 |
3.18 |
1.0 |
3300 |
|
0.004 |
0.12 |
4.24 |
1.3 |
4400 |
|
0.005 |
0.15 |
5.31 |
1.6 |
5500 |
|
0.006 |
0.18 |
6.37 |
1.9 |
6600 |
|
0.007 |
0.21 |
7.43 |
2.3 |
7700 |
|
0.008 |
0.24 |
8.49 |
2.6 |
8800 |
|
0.009 |
0.27 |
9.55 |
2.9 |
9900 |
|
0.010 |
0.30 |
10.61 |
3.2 |
11000 |
|
0.020 |
0.60 |
21.22 |
6.4 |
22000 |
|
0.030 |
0.90 |
31.83 |
9.7 |
33000 |
|
0.040 |
1.20 |
42.44 |
12.9 |
44000 |
|
0.050 |
1.50 |
53.06 |
16.1 |
55000 |
|
0.060 |
1.80 |
63.67 |
19.3 |
65900 |
|
0.070 |
2.10 |
74.28 |
22.5 |
76900 |
|
0.080 |
2.40 |
84.89 |
25.8 |
87900 |
|
0.090 |
2.70 |
95.50 |
29.0 |
98900 |
|
0.100 |
3.00 |
106.11 |
32.3 |
109800 |
|
0.200 |
6.00 |
212.22 |
64.4 |
219700 |
Note: – Essex Heating Services accepts no liability for the accuracy of this table and the figures that it contains. You should check the data before using it to carry out any adjustments. (Please refer to the Gas Regulations before implementation – this is your responsibility).