Do you have a break-even algorithm for capital improvements that save money?

[Alex Gunderson]

Down here, these huge tanks (they're fifteen feet long) are certified at the factory, AFAIK, and that's the end of it.

Every dozen (or so) years they replace the regulators.

And, every new delivery company runs a complete hour-long inspection of the tank, fittings, and premises (inside & outside the house).

I doubt these things are exploding left and right, so, for safety, that's apparently just fine.

I'll tell you the least of my worries is the tank causing a hazard.

I'd worry more about a thousand other items in the house, not the least of which are my kid's friends.

[Alex Gunderson]

I have a whole bunch of tanks, carbon dioxide, acetylene, oxygen, scuba, etc., and I know all about the certification for those.

It's no big deal.

The only ones afraid of it are the ones who never had it done (and those people are afraid of everything anyway).

[Alex Gunderson]

In general, and this is a long shot because it's a general equation, the crap that the construction guys puts in saves THEM a dollar a job, but only saves you a total of 1 dollar, which you don't even get to save because they typically charge you something like double what it would cost you for the same materials.

So, as an algorithm, I do it myself, and I buy the best material. If I pay someone to do it, they often buy the cheapest material, or, charge me double than it would cost me for better material.

In the end, the DIY wins because they LEARN (if that's your shtick). And, the DIY gets the absolute best materials. At the lowest total costs.

The tradeoff is time. Lots of time in most cases.

[micky]

But what does the 'G' stand for in LPG?

Propane at room temperature and pressure is a gas. It changes to a liquid when it's under pressure.

The rest of what you say may well be true.

When my friend was sick, they hired an LPN, a liquid petroleum nurse. She would run all over the place.

[chaniarts]

it's also called Liquified Petroleum Gas, which by definition is petroleum gas stored as a liquid, and by definition, is not a gas.

propane in a tank is liquid, and thus there is very little 'gas' in the tank, so the pressure is far less than a tank of only gas that is not actually stored in a liquid state.

think of a dewar flask of liquid nitrogen. it's not pressurized at all, and the nitrogen is changing from liquid to gas all the time if the flask is opened, due to rising temp.

[hrhofmann]

I make my own beer, and I use beer gas in a cast steel cylinder to drive it out of a spigot on my beer fridge. That's how I know about the pressure certification requirement.

What is "beer gas"? I know the results of drinking too much beer, but it doesn't come in any cast steeel cylinders!!

[Alex Gunderson]

Does anyone know how often a 1,000 gallon propane tank is pressure certified?

How long do these huge propane tanks "typically" last anyway?

And how often, after their made, are they tested for pressure?

Zero? Once every 20 years?

Any idea? Any experience?

[Alex Gunderson]

Googling for how much pressure is in a propane tank, I find this blurb:

"The pressure in a propane tank varies with the temperature of the liquid in it. Volume is not a factor. At -44°F the pressure is 0 psi. As the temperature increases from there, so does the pressure. At 0°F you have about 28 psi, at 32°F about 60 psi. At 72°F about 130 psi and at 100°F close to 200 psi."

So, these huge steel things are only holding a couple hundred PSI.

How often are they 'pressure certified' anyway?

When do you normally 'expire' a propane tank anyway?

20 years? 40 years? 100 years?

[krw]

Government?

Or cold enough.

It is.

Probably stunk like rotten eggs, too.

[krw]

Right but if that Dewar is sealed, the pressure will increase dramatically. LP has a fairly high boiling point and can exist as a liquid at room temperature at a fairly low pressure. If you're really interested in this stuff you can look up the "phase diagrams" of various chemicals. I'd look up Nitrogen now but I'm waiting to board a flight and disconnected.

[Ed Pawlowski]

The 20# tanks for a grill are dated and expire or have to be tested after 12 years.

Large tanks must conform to certain specifications of ASME (Amer.Soc.Mech.Eng) but I don't know about testing. Most pressure vessels are checked for corrosion using ultrasonic instruments.

[Stormin Mormon]

CY: yeah, but it's compressed government.

CY: Ha, you're going to educate usenet readers?

CY: We knew that.

CY: Lot of tanks that CNG gets....

CY: Only if she was properly odorized.

. Christopher A. Young Learn about Jesus

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