Wallet cards for clocking gas meters?

JohnNY · September 2020

Hello,
Does anyone know where I can purchase or otherwise acquire printed wallet cards for clocking gas meters?
Best to all,
John Cataneo

rick in Alaska · September 2020

I just use the timer on my phone and then the calculator. I take 3,600,000 and then divide by the time in seconds to make one cubic foot. Seems just as easy as using a chart.
Rick

HVACNUT · September 2020

Try getting a printout from the utility. I can't even remotely remember when I laminated this. Keyspan has been gone for a while.

Larry Weingarten · September 2020

Hi, How about taking a picture of what HVACNUT posted and just keeping it on your phone for quick reference?

Yours, Larry

STEVEusaPA · September 2020

Here's @HVACNUT's in a pdf. I have one printed/laminated, and the pdf on my phone.

JohnNY · September 2020

So, the takeaway here is I gotta make my own?

ratio · September 2020

That's what it sounds like. Too bad, I was interested in one also.

Guess I'll fire up ol' Word the next time I'm idled at the office.

ch4man · September 2020

its easier to learn the math...
Ricks math can be off and hvacnuts cheatsheet is only good for 7" gas. you need to modify the formula for 2 lb metering pressure systems....

7" metering system;
3600 divided by the seconds to pass 1 cubic foot equals cfh per hr.

2lb metering system;
3600 divided by the seconds to pass 1 cubic foot times 1.12 equals cfm per hr.

multiply either by the heat content of the local gas gives out btuh input.

STEVEusaPA · September 2020

I posted a pdf. Print it, laminate it if you want, or save and look at it on your phone.

ratio · September 2020

ch4man said:
…
2lb metering system;
3600 divided by the seconds to pass 1 cubic foot times 1.12 equals cfm per hr.
…

How did you derive this? I'd really like a formula that I could plug in meter pressure & get a correction factor of some kind.

JohnNY · September 2020

STEVEusaPA said:
I posted a pdf. Print it, laminate it if you want, or save and look at it on your phone.

Thank you. I think that font is hard to read at small sizes but I'll check it out.

ch4man · September 2020

ratio said:

ch4man said:
…
2lb metering system;
3600 divided by the seconds to pass 1 cubic foot times 1.12 equals cfm per hr.
…
How did you derive this? I'd really like a formula that I could plug in meter pressure & get a correction factor of some kind.

i know some guys who work for the gas company, very smart guys and the gas co who mfg'd gas that was made on the banks of the Mississippi around the turn of the century.
as i was told;

a gas meter will pass 12% more gas at 2 PSI than 1/4 psi.
a gas meter will pass 2% more gas at 14" WC than 1/4 psi.

this is why you gas bill has correction factors. most gas meters are temperature compensated but not pressure compensated.

now think of the physical size of a tank of nitrogen at what a couple few thousand psi. the weld shop sells then as 80 cubic feet. that tank aint that large on the outside

Mike_Sheppard · September 2020

Pressure correction:

(14.74 + line pressure) / 14.74 = Y

(Y x 3600 x Dial Size) / Seconds for revolution = CFH

Multiply by btu content of the gas to get BTU/hr

ratio · September 2020

Mike_Sheppard said:
Pressure correction:

(14.74 + line pressure) / 14.74 = Y

(Y x 3600 x Dial Size) / Seconds for revolution = CFH

Multiply by btu content of the gas to get BTU/hr

Is line pressure inches or pounds? 14.74 is atmospheric pressure & may be corrected for elevation?

GW · September 2020

Just have a pic of the chart and create a folder. I have Google Pics app, I have the chart in my Technical folder.

ch4man · September 2020

my information falls right in line with mike Sheppards math when going from a 7" system to a 2lb system.
thx Mike, i never knew the math behind the correction factors

mattmia2 · September 2020

ratio said:

Mike_Sheppard said:
Pressure correction:

(14.74 + line pressure) / 14.74 = Y

(Y x 3600 x Dial Size) / Seconds for revolution = CFH

Multiply by btu content of the gas to get BTU/hr

Is line pressure inches or pounds? 14.74 is atmospheric pressure & may be corrected for elevation?

You have to multiple/divide like units for them to cancel out.

Mike_Sheppard · September 2020

@ratio sorry about that - yes the line pressure is in PSIG.

To be more specific:

(Atmospheric pressure + Line Pressure PSIG) / Atmospheric BASE pressure

“Atmospheric pressure” gets corrected by you based on your altitude.

”Atmospheric BASE pressure” is the atmospheric pressure that your gas company references. The altitude that the gas company uses and the altitude at your job site may not be the same.

As for the rest of the equation.

3,600 = The amount of seconds in an hour. Because we are trying to calculate cubic feet per -hour- (CFH) by counting the amount of seconds it takes a certain dial to make a revolution.

After you get CFH figured out you just have to multiply it by the BTU content of the gas to get BTU/Hr.

You can call your gas company to figure out the BTU per cubic foot of gas they supply. Where I am at it is about 1,020 btu per cu/f.

There is also a temperature correction that I never use because the difference is so small. And I also do commercial/industrial and most of the meters I deal with are already temperature and pressure corrected.

gerry gill · September 2020

Talk to the Bacharach rep. They gave me a stack of them many years ago. I don’t know off hand if they still have them or not.

Zman · September 2020

@Mike_Sheppard , Thanks for posting the formula, that is super useful for both clocking boilers and calculating gas usage on 2# meters.
The attached doc shows how much the BTU content and specific gravity varies in the high altitude region of the west. The process gets a little more complicated when you throw derated gas into the equation. To determine the PSI at altitude, this is a useful resource https://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html

Wallet cards for clocking gas meters?

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