# Gas meter firing rate calcs

Discussion in 'Computer Support' started by Martik, Nov 30, 2006.

1. ### MartikGuest

My gas meter is metric with one of the dials calibrated to .01 cu meters. If
one revolution takes 16 secs, what is the gas consumption rate according to
the table below?

I get 80,000btu as follows:

1 cu ft = 12^3 cu in or 1728
1 cu meter = 39.37^3 cu in or 61023
..01 cu meters = 610 cu in
therefore to extrapolate to 1 cu ft: multiply 16 secs by = 1728/610 or 2.8
which is 45 secs

Does this make sense?

-------------------------------------------------------------

Checking the Firing Rate -"Clocking the Meter"

Checking the firing rate of a furnace is a very important element of the
installation procedure. Over-firing can cause premature heat exchanger
failure. This is done by measuring the time it takes to consume 1 cubic
foot of gas.

When performing this procedure it is important to activate the furnace for
about 10-15 minutes, and all the other gas appliances are turned off.
Adjust inlet gas pressure to between 5 and 7 inches water column then time
the meter for 2 revolutions and then divide by 2 to get the time for one
revolution. Need to check meter size (1 CuFt or 10 CuFt).

The following table shows approximate gas consumption (measured in cubic
feet per hour), and the gas input (measured in Btu/Hr), based on Natural gas
whose caloric value ranges from 900 to 1050 Btu/cu. ft. We are assuming
1000 Btu/cu. ft.

Gas Input (Btu/Hr) =
(Caloric Value of Gas x 3600) / Meter Time (seconds)

This chart assumes a 1 CuFt meter size

Seconds
per cubic
feet Consumption
cubic feet
per hour Gas input
btu/hr
@ 1000 btu/cu ft
20 180 180,000
22 164 164,000
24 150 150,000
26 138 138,000
28 129 129,000
30 120 120,000
32 113 113,000
34 106 106,000
36 100 100,000
38 95 95,000
40 90 90,000
42 86 86,000
44 82 82,000
46 78 78,000
48 75 75,000
50 72 72,000
52 69 69,000
54 67 67,000
56 64 64,000
58 62 62,000
60 60 60,000
62 58 58,000
64 56 56,000
66 54 54,000
68 53 53,000
70 51 51,000
72 50 50,000
74 48 48,000
76 47 47,000
78 46 46,000
80 45 45,000
82 44 44,000
84 43 43,000
86 42 42,000
88 41 41,000
90 40 40,000

Martik, Nov 30, 2006

2. ### SgtMinorGuest

I got 81,592 Btu/hr, as follows:
1 hour = 3600 seconds, divided by 16 seconds per revolution = 225
revolutions, which equals 2.25 cubic meters.
1 cubic meter = 35.31 cubic feet.
1 cubic foot contains approximately 1027 Btu.
Thus 2.25 x 35.31 x 1027 = 81,592.
If you rate a cubic foot at 1,000 btu, consumption = 79,448.

SgtMinor, Dec 1, 2006

3. ### MartikGuest

That makes sense and no tables required!

Thanks

Martik, Dec 1, 2006