Estimating Rate; Clocking The Gas Meter - Beckett CG15 Manual

Manifold to Furnace Pressure Drop vs. Rate -
Figure 17 — Manifold to Furnace Pressure Drop vs Rate CG50*
6000
5000
4000
3000
2000
1000
0
0 0.5
Manifold to Combustion Chamber Pressure Drop (in. WC)
* Charts represent both natural and propane gas.

Estimating Rate

Manifold to Furnace Pressure information can be used to
estimate the burner's firing rate when it is not possible
to clock a meter for the rate. To estimate the burner's
firing rate:
1. Measure the furnace pressure over fire.
2. Measure the manifold pressure (at the manifold
pressure test connection).
3. Subtract the furnace pressure from the manifold
pressure.
4. Compare the result to the data in Figure 15 through
Figure 17 as appropriate for your burner.

Clocking the Gas Meter

If the burner is firing natural gas it may be possible to
verify the firing rate by "clocking" the gas meter:
1. Locate the gas meter and examine its display to be
sure that you can determine a 1 cubic foot usage of
gas and that the meter is temperature compensated.
( Figure 18 )
2. Contact the gas utility to find the heating value of
the gas. It can vary from about 950 BTU/ft3 to about
1,100 BTU/ft3.
3. Examine the gas piping to know of any other gas
appliances connected to it. Turn them off so that
only this burner is using gas from the meter.
CG15, CG25, CG50 Burner Manual, Form No. 6104BCG50
CG50
1 1.5 2
Pressure Drop, In. WC
2.5 3 3.5
4. Start the burner and use a stopwatch to measure the
number of timed seconds it takes for the burner to
fire 1 cubic foot of gas.
5. Calculate the firing rate in BTU/Hr. using the
following equation:
Firing rate BTU/Hr. = Heating value (BTU/Ft
3,600 ÷ Timed seconds
For example, if the heating value is 1,050 BTU/Ft3
and you timed 1 cubic foot of gas at 42 seconds
then firing rate BTU/Hr = 1050 x 3,600 ÷ 42 which
calculates to 90,000 BTU/Hr.
Figure 18 — Typical Gas Meter Layout
0 9
1
2 8
8
7
3
7
6
4
5
CG50.5S
CG50.4S
CG50.3S
CG50.2S
CG50.1S
4 4.5
0 1 0 9
0 1
1
9 9
2 2 8 8
7
3
3 7
4 6
6 4
6
5 5 5
Section: Start Up And Operation —
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