auto-changeover propane regulator

[Dan Lanciani]

Are there auto-changeover propane regulators (or separate auto-changeover
devices) for fixed (2x 1000 gallon) tanks? The propane company putting in
my tanks had not heard of this, and Google searches turn up only ones for
small RV tanks. Ideally something with a remote indicator would be nice;
I could arrange for the computer to email me to call for a delivery...

Dan Lanciani
ddl@danlan.*com

 

[vaughn]

How much gas flow are you planning on? Will the RV regulator handle it? I have
an auto-switch regulator on two 100-pound tanks for my standby generator. The
regulator doesn't care of they are 5 gallon tanks or 10,000 gallon tanks, it
just switches when the vapor pressure drops in one tank. Those auto-shift
regulators are not just used in the RV world, they are used all over the south
in places where rental 100# tanks are used for cooking and DHW.

I have never seen a remote indicating one, but I am not in the 'biz.

Vaughn

 

[vaughn]

Even without that technology, they'll come and top up on a regular
basis once your useage pattern has been established.

I don't know that the OP's tanks are for, but remember that standby generators
have no constant fuel usage pattern, expect whatever gas is used by periodic
exercising. Also, in the middle of a long general power failure, it is
somewhere between difficult and impossible to get a fuel delivery.

Vaughn

 

[Dan Lanciani]

| On Jun 24, 5:41=A0pm, ddl@danlan.*com (Dan Lanciani) wrote:
| > Are there auto-changeover propane regulators (or separate auto-changeover
| > devices) for fixed (2x 1000 gallon) tanks? =A0The propane company putting=
| in
| > my tanks had not heard of this, and Google searches turn up only ones for
| > small RV tanks. =A0Ideally something with a remote indicator would be nic=
| e;
| > I could arrange for the computer to email me to call for a delivery...
| >
| > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Dan Lanci=
| ani
| > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 ddl@danla=
| n.*com
|
| Is there a reson you can't use the rv ones?

Yes, two reasons. First, as far as I can tell, the RV units are all low
pressure regulators. That is, they drop the pressure to the final ~11" WC.
I'm looking for a "first stage" regulator that drops the pressure to 10psi
for the longish pipe to the house and generator. Second, most of the RV
regulators have relatively low capacity. I think I found one that would
probably have been enough (if it wasn't a misprint) but it still had the
low-pressure output. The funny thing is that some (most?) of the RV units
appear to consist of dual regulators with the first stage high-pressure
switchover regulator coupled directly to the second stage regulator. It
might be possible to take them apart, but I suspect that would void any
safety listing.

| Are you using the same
| pressure? I've not seen any with remote indicators though.

The RV ones have remote indicators which is what caught my eye in the
first place. Unfortunately, after extensive additional Googling I've
come to the conclusion that what I want just doesn't exist in the US.
They are certainly available in the UK and I found a nice one in Israel,
but here again I'd be worried about safety listing and codes if I imported
one.

I may have to go back to the idea of a remote level readout. I initially
dropped this because the propane company said they used to do it but that
the product they used was no longer available. Now that I think about it
they may have been talking about a comprehensive service that alerted
*them* to the level in my tanks. I want to alert me. It looks like I
should be asking for "remote ready float gauges" to which several kinds
of senders can be attached. I'd like something hard-wired and with an
output I can connect to a computer. The "residential" ones look to be
wireless with just a visual bar graph, but some of the "commercial" ones
look better.

Dan Lanciani
ddl@danlan.*com

 

[You]

Is there a reson you can't use the rv ones? Are you using the same
pressure? I've not seen any with remote indicators though.

there is ONE BIG reason you can't RV tanks on a generator of any size.
(10Kw) they are Vapor withdraw type tanks and they don't have enough
surface area to allow the propane liquid to boil off into gas, without
freezing up the tank.... duh... anyone who has ever tried it knows
this...

 

[vaughn]

there is ONE BIG reason you can't RV tanks on a generator of any size.
(10Kw) they are Vapor withdraw type tanks and they don't have enough
surface area to allow the propane liquid to boil off into gas, without
freezing up the tank.... duh... anyone who has ever tried it knows
this...

Huh? The OP was asking about 2-1000 gallon tanks. That is plenty of surface
area unless we are talking about sub-zero temperatures. The flow capacity of
the regulator is a bigger concern.

Vaughn

 

[David Lesher]

ddl@danlan.*com (Dan Lanciani) writes:

I may have to go back to the idea of a remote level readout. I initially
dropped this because the propane company said they used to do it but that
the product they used was no longer available. Now that I think about it
they may have been talking about a comprehensive service that alerted
*them* to the level in my tanks. I want to alert me. It looks like I
should be asking for "remote ready float gauges" to which several kinds
of senders can be attached. I'd like something hard-wired and with an
output I can connect to a computer. The "residential" ones look to be
wireless with just a visual bar graph, but some of the "commercial" ones
look better.

I too need a propane tank level sensor scheme. I found
<http://www.rochestergauges.com/Pages/PDFs/R3D.pdf> mentioned.

 

[vaughn]

No chance except in very hot conditions. The latent heat requirements
of the propane soon cool the tank down to a point were the gas won't
vapourise off.

That is a huge overstatement. If what you say were true, then nobody would use
vapor directly from a propane tank. But actually vapor withdrawal is the most
common method!. How much gas you can draw from a given propane tank depends on
the tank's size and the outside temperature. Scroll down on this page for a
table that gives you the maximum BTUs based on tank size and outside
temperature. http://www.propane-generators.com/propane_usage.htm

I can connect a 20# BBQ tank to my 4000 watt generator at full load and the tank
will drop perhaps 10 degrees in temperature. I can draw the tank totally empty
without the slightest concern for tank freeze up. With that same generator on
a 100# tank, the cooling is barely detectible. From there, you can do the math
to extrapolate to the comparatively huge tanks the OP is considering.

Vaughn


..

 

[The Daring Dufas]

That is a huge overstatement. If what you say were true, then nobody would use
vapor directly from a propane tank. But actually vapor withdrawal is the most
common method!. How much gas you can draw from a given propane tank depends on
the tank's size and the outside temperature. Scroll down on this page for a
table that gives you the maximum BTUs based on tank size and outside
temperature. http://www.propane-generators.com/propane_usage.htm

I can connect a 20# BBQ tank to my 4000 watt generator at full load and the tank
will drop perhaps 10 degrees in temperature. I can draw the tank totally empty
without the slightest concern for tank freeze up. With that same generator on
a 100# tank, the cooling is barely detectible. From there, you can do the math
to extrapolate to the comparatively huge tanks the OP is considering.

Vaughn

In a very cold climate, the tank could be buried so as to absorb heat
from the ground but I haven't seen it done around here in the Southeast.
Around here, cold is a relative term.

TDD

 

[The Daring Dufas]

This is true. We run cars on propane over here. The liquid propane
is vapourised in a heat exchange device that draws water from the
coolant jacket of the IC engine. Many are converted from petrol,
there is an annular ring fitted between the carburretor and the inlet
manifold that injects the gas through a ring of holes. Needle jet
controls the gas on the liquid side of the vapouriser device.

Here, Alabama Gas has been running their vehicles on natural gas for
many years. You can see the CNG tanks on the beds of their service
trucks. Those vehicles have a similar setup to those that run on
Propane.

TDD

 

[vaughn]

In the hospital where I worked we had liquid oxygen. It held about
three tons of LOXWe even needed a heat exchanger on that to evaporate
the LOX. It was just like a big car radiator.

Aha. There is a difference

LOX is cyrogenic and usually stored at a very low pressure in an insulated but
vented vessel . Propane is stored at ambient temperature in a medium pressure
UNinsulated pressure vessel. Even tiny portable, LOX bottles have heat
exchangers built in to vaporize the liquid. Not so for propane because the tank
itself is usually sufficient to act as the heat exchanger.

Vaughn

 

[The Daring Dufas]

Aha. There is a difference .The natural gas is just compressed. The
propane is liquid and has to be evaporated off. I suppose in a warm
climate you might not need an evaporator but even here in the UK you
do.
In the hospital where I worked we had liquid oxygen. It held about
three tons of LOXWe even needed a heat exchanger on that to evaporate
the LOX. It was just like a big car radiator. Even so it used to
freeze up. We had to clear the ice off with a steam lance in certain
weather conditions.

You know, I'm not sure if the gas company is not liquefying the natural
gas, the tanks look very substantial and the technology for liquefying
NG is quite mature. I know some guys who work for Alabama gas and I will
ask them about it. In another thread there was a discussion about O2 and
the tanks. I mentioned the rather large LOX tank at the University
Hospital complex here in town that I want to know more about.

TDD

 

[[email protected]]

You know, I'm not sure if the gas company is not liquefying the natural
gas, the tanks look very substantial and the technology for liquefying
NG is quite mature. I know some guys who work for Alabama gas and I will
ask them about it. In another thread there was a discussion about O2 and
the tanks. I mentioned the rather large LOX tank at the University
Hospital complex here in town that I want to know more about.

Unlike propane, natural gas can't be in the liquid state at room temperature,
so must be transported cryogenically or compressed under extreme pressure.
Cryogenics are complicated, heavy, and require energy themselves. A highly
compressed flammable gas isn't exactly a good vehicle fuel either; not enough
can be carried safely.

 

[The Daring Dufas]

Unlike propane, natural gas can't be in the liquid state at room temperature,
so must be transported cryogenically or compressed under extreme pressure.
Cryogenics are complicated, heavy, and require energy themselves. A highly
compressed flammable gas isn't exactly a good vehicle fuel either; not enough
can be carried safely.

Aren't there many LNG tankers plying the worlds oceans? I have never
fiddled with any liquefied gaseous fuels other than what's commonly
for sale around here. Butane, propane, MAAP and a few other fuels for
brazing or welding. I saw a new one on sale at Home Depot the other
day that goes along with a new tank and torch design. I don't recall
the name and I'm too lazy right now to look for it. *snicker*

TDD

 

[m II]

Unlike propane, natural gas can't be in the liquid state at room
temperature,
so must be transported cryogenically or compressed under extreme pressure.
Cryogenics are complicated, heavy, and require energy themselves. A
highly
compressed flammable gas isn't exactly a good vehicle fuel either; not
enough
can be carried safely.

Wrong! Where do you idiots get this information?
Propane liquefies about 150 PSI at room temperature. NG takes much more
pressure.

Mike

 

[m II]

Huh? The OP was asking about 2-1000 gallon tanks. That is plenty of
surface area unless we are talking about sub-zero temperatures. The flow
capacity of the regulator is a bigger concern.

Vaughn

Just killfilter that idiot. I did years ago.

Mike

 

[m II]

Huh? The OP was asking about 2-1000 gallon tanks. That is plenty of
surface area unless we are talking about sub-zero temperatures. The flow
capacity of the regulator is a bigger concern.

Vaughn

Just killfilter that idiot. I did years ago.

Mike

 

[[email protected]]

Aren't there many LNG tankers plying the worlds oceans?

Yes, they're essentially dewar flasks carrying LNG at some -250F. That's
pretty difficult to do in a car.

I have never
fiddled with any liquefied gaseous fuels other than what's commonly
for sale around here. Butane, propane, MAAP and a few other fuels for
brazing or welding. I saw a new one on sale at Home Depot the other
day that goes along with a new tank and torch design. I don't recall
the name and I'm too lazy right now to look for it. *snicker*

Butane is a liquid at room temperature an pressure. Propane can be a liquid
at room temperature with a pressure of a few atmospheres; easily done in your
backyard grill tank. Methane (natural gas) isn't so easy. It cannot be a
liquid at room temperature at any pressure. Actually, it has no phase change
at room temperature, at any pressure. LNG is totally unsuitable for mobile
use.

 

[[email protected]]

Wrong! Where do you idiots get this information?

Certainly a better place than do you!

Propane liquefies about 150 PSI at room temperature.

At least I can read. You should try it some day.

NG takes much more pressure.

Methane doesn't liquefy *AT ALL* at room temperature. Its critical point (the
temperature and pressure at which it will no longer liquefy) is -115F at
673psia. Look it up, then come crawling back with your tail between your
legs. ...or not.

 

[The Daring Dufas]

Wrong! Where do you idiots get this information?
Propane liquefies about 150 PSI at room temperature. NG takes much more
pressure.

Mike

OK, I got un-lazy and looked it up. I learn something new every day.

http://en.wikipedia.org/wiki/Liquefied_natural_gas

TDD