Measuring Propane Gas Pressure

retiredmt

I'm hoping this is an easy fix. I need to know if there is some type of gauge that can be installed on my incoming propane gas line that will show if there is a pressure issue possible due to a frozen and partially frozen regulator. I would think that the gas company can install one at the regulator by the tank (see picture), but that regulator might be fine in the super cold weather and the one by the house might be frozen. I'm asking because, as a homeowner, I would like to have some quick definitive way to tell if my regulators are freezing.

hot_rod

There are pressure taps on the tank valve as well as the regulators. You can mount permanent gauges or get one of these Rego test gauge kits.

I always had a good liquid filled gauge on my 500 gallon tanks.

If the reg is outside at the house, you would want to protect the gauge somehow.

Download the manual for the brand of regulators you have to get the gauge spec. Some are 1/4" npt, some are 1/8" gauge ports.

Maybe have your LP supplier help, to assure you get the correct gauge range, etc.

retiredmt

hot_rod said:

There are pressure taps on the tank valve as well as the regulators. You can mount permanent gauges or get one of these Rego test gauge kits.

I always had a good liquid filled gauge on my 500 gallon tanks.

If the reg is outside at the house, you would want to protect the gauge somehow.

Download the manual for the brand of regulators you have to get the gauge spec. Some are 1/4" npt, some are 1/8" gauge ports.

Maybe have your LP supplier help, to assure you get the correct gauge range, etc.

My understanding is that the pressure is so low after the 2nd stage regulator that a pressure gauge wouldn't be able to measure. Is that true?

pecmsg

retiredmt said:

There are pressure taps on the tank valve as well as the regulators. You can mount permanent gauges or get one of these Rego test gauge kits. I always had a good liquid filled gauge on my 500 gallon tanks. If the reg is outside at the house, you would want to protect the gauge somehow. Download the manual for the brand of regulators you have to get the gauge spec. Some are 1/4" npt, some are 1/8" gauge ports. Maybe have your LP supplier help, to assure you get the correct gauge range, etc.

My understanding is that the pressure is so low after the 2nd stage regulator that a pressure gauge wouldn't be able to measure. Is that true?

Then how do we measure it?

0 - 2# gauge

hot_rod

Notice in this example, they have 3 different gauge ranges. 200 psi at the tank, 30 psi on stage 1, maybe a 5 psi gauge at the second stage.
The final stage needs to be a low pressure gauge to get an accurate number. Many pros use a manometer to read pressure below 1 psi.

What can happen is under extreme cold conditions the static pressure look good, as soon as the boiler fires you see the final gauge drop, if inadequate supply pressure.

So you need to measure with nothing firing, then with all the LP loads on.

LP service guys know this procedure, might be best left to them.

Plus your clothes wont smell like LP for weeks

EBEBRATT-Ed

LP is usually 11-13" inside the house which is about 1/2 a PSI.

You need to try and find out if the regulator is freezing or the propane. They can add additive to the propane to prevent this also to keep condensation water out of the tank.

vhauk

propane has been used as a refrigerant. It acts exactly like any refrigerant. California actually converted some of their state vehicles to propane air conditioning during the 70’s with the ozone scare. After a couple of the modified vehicles were involved in accidents it was decided that it wasn’t a great idea. The pressure in the tank will have a direct correlation to the temperature of the tank, unless there is not enough heat energy being transferred liquid propane to maintain vapor pressure. And the pressure drops, as the tank actually gets colder than ambient. It’s a problem with L P gas in very cold weather. 

hot_rod

A regular outdoor thermometer by the reg in the tank would give you some more data. I doubt that buried tank is reaching ambient temperature?

Do the regulators belong to you or the lp company?
. They switch them out on a regular basis, especially if you are having supply issues

retiredmt

hot_rod said:

A regular outdoor thermometer by the reg in the tank would give you some more data. I doubt that buried tank is reaching ambient temperature?

Do the regulators belong to you or the lp company?
. They switch them out on a regular basis, especially if you are having supply issues

Regulators belong to the LP company. The issue occurred when we recently hit record lows of -35 degrees F. The thought is that the regulator(s) froze. Or at least partially froze. I thought if I could put some type of gauge post regulator (both after the tank regulator and after the one on the house), then I could tell pretty quickly that it was a regulator issue.

vhauk

at -35 degrees propane will have a vapor pressure of about 2 or 3 psig. Your regulator can’t MAKE pressure that isn’t there 

vhauk

Additionally if gas propane is being drawn from the tank, the vaporization of the liquid propane to gas will further reduce the temperature of the tank. At -40 degrees propane has 0 psig vapor pressure. 

Dave Carpentier

vhauk said:

At -40 degrees propane has 0 psig vapor pressure. 

If you were to draw a vacuum on the tank, would more propane boil off and make an available gas ?

vhauk

Yes. It’s all about the vapor “pressure.”  But if you did draw a vacuum to “boil” more propane, the tank would get colder still. 

hot_rod

Is this a new installation, or has it worked in the past at these conditions. How deep is the tank buried? What is your frost level? Looks like you have snow cover which helps the tank temperature. The vent opening wants to point down to prevent any moisture from freezing inside, hard to tell from that pic how it is mounted.

We had vaporizers on the large lp boiler systems at the ski resorts at 8000, I’ve never seen a small residential system needing vaporizers for cold weather.

Any neighbors having issues with lp tanks or regs?

It’s not a big job to switch out a reg, and they are not real $$ if you suspect moisture in them causing the
Problem. Certainly an inexpensive fix compared to a home freeze up, or being uncomfortable in your home.

retiredmt

hot_rod said:

Is this a new installation, or has it worked in the past at these conditions. How deep is the tank buried? What is your frost level? Looks like you have snow cover which helps the tank temperature. The vent opening wants to point down to prevent any moisture from freezing inside, hard to tell from that pic how it is mounted.

We had vaporizers on the large lp boiler systems at the ski resorts at 8000, I’ve never seen a small residential system needing vaporizers for cold weather.

Any neighbors having issues with lp tanks or regs?

It’s not a big job to switch out a reg, and they are not real $$ if you suspect moisture in them causing the
Problem. Certainly an inexpensive fix compared to a home freeze up, or being uncomfortable in your home.

Thanks for the input. Actually I live at 8000 feet and am adjacent to a ski resort. The recent cold spell of -35 was an anomaly and once it warmed to say -25 the boiler was working fine. Never had an issue like this (it's only 3 years old). Some neighbors also had some issues and one plumber mentioned that even his propane boiler didn't function right until it warmed up. What I'm trying to find out is if there are gauges (or something) that I can put post regulator that will tell me that the issue is definitely propane related vs trying to get Lochinvar technical support on the phone and troubleshoot the boiler. The LP company said that it isn't unusual at these low temperatures for the regulators to freeze, yet they don't offer any solution to prevent it.

hot_rod

retiredmt said:

hot_rod said:

Is this a new installation, or has it worked in the past at these conditions. How deep is the tank buried? What is your frost level? Looks like you have snow cover which helps the tank temperature. The vent opening wants to point down to prevent any moisture from freezing inside, hard to tell from that pic how it is mounted.

We had vaporizers on the large lp boiler systems at the ski resorts at 8000, I’ve never seen a small residential system needing vaporizers for cold weather.

Any neighbors having issues with lp tanks or regs?

It’s not a big job to switch out a reg, and they are not real $$ if you suspect moisture in them causing the
Problem. Certainly an inexpensive fix compared to a home freeze up, or being uncomfortable in your home.

Thanks for the input. Actually I live at 8000 feet and am adjacent to a ski resort. The recent cold spell of -35 was an anomaly and once it warmed to say -25 the boiler was working fine. Never had an issue like this (it's only 3 years old). Some neighbors also had some issues and one plumber mentioned that even his propane boiler didn't function right until it warmed up. What I'm trying to find out is if there are gauges (or something) that I can put post regulator that will tell me that the issue is definitely propane related vs trying to get Lochinvar technical support on the phone and troubleshoot the boiler. The LP company said that it isn't unusual at these low temperatures for the regulators to freeze, yet they don't offer any solution to prevent it.

The gauge port is on the side of all regulators, attached pic of Rego brand, which looks like yours. Remove the plug screw in the gauge.

But the gauge will just tell you the reg is frozen or not working If the tank is too cold, not much you can do at the reg?

pecmsg

retiredmt said:

hot_rod said:

Is this a new installation, or has it worked in the past at these conditions. How deep is the tank buried? What is your frost level? Looks like you have snow cover which helps the tank temperature. The vent opening wants to point down to prevent any moisture from freezing inside, hard to tell from that pic how it is mounted.

We had vaporizers on the large lp boiler systems at the ski resorts at 8000, I’ve never seen a small residential system needing vaporizers for cold weather.

Any neighbors having issues with lp tanks or regs?

It’s not a big job to switch out a reg, and they are not real $$ if you suspect moisture in them causing the
Problem. Certainly an inexpensive fix compared to a home freeze up, or being uncomfortable in your home.

Thanks for the input. Actually I live at 8000 feet and am adjacent to a ski resort. The recent cold spell of -35 was an anomaly and once it warmed to say -25 the boiler was working fine. Never had an issue like this (it's only 3 years old). Some neighbors also had some issues and one plumber mentioned that even his propane boiler didn't function right until it warmed up. What I'm trying to find out is if there are gauges (or something) that I can put post regulator that will tell me that the issue is definitely propane related vs trying to get Lochinvar technical support on the phone and troubleshoot the boiler. The LP company said that it isn't unusual at these low temperatures for the regulators to freeze, yet they don't offer any solution to prevent it.

One issue that may not be helping you is how Full is the tank?
A tank that's low gets colder quicker due to the refrigeration effect as the LP boils off.

retiredmt

pecmsg said:

retiredmt said:

hot_rod said:

Is this a new installation, or has it worked in the past at these conditions. How deep is the tank buried? What is your frost level? Looks like you have snow cover which helps the tank temperature. The vent opening wants to point down to prevent any moisture from freezing inside, hard to tell from that pic how it is mounted.

We had vaporizers on the large lp boiler systems at the ski resorts at 8000, I’ve never seen a small residential system needing vaporizers for cold weather.

Any neighbors having issues with lp tanks or regs?

It’s not a big job to switch out a reg, and they are not real $$ if you suspect moisture in them causing the
Problem. Certainly an inexpensive fix compared to a home freeze up, or being uncomfortable in your home.

Thanks for the input. Actually I live at 8000 feet and am adjacent to a ski resort. The recent cold spell of -35 was an anomaly and once it warmed to say -25 the boiler was working fine. Never had an issue like this (it's only 3 years old). Some neighbors also had some issues and one plumber mentioned that even his propane boiler didn't function right until it warmed up. What I'm trying to find out is if there are gauges (or something) that I can put post regulator that will tell me that the issue is definitely propane related vs trying to get Lochinvar technical support on the phone and troubleshoot the boiler. The LP company said that it isn't unusual at these low temperatures for the regulators to freeze, yet they don't offer any solution to prevent it.

One issue that may not be helping you is how Full is the tank?
A tank that's low gets colder quicker due to the refrigeration effect as the LP boils off.

1000 gallon tank, 70% full.

HomerJSmith

Why not just raise the temp around the regulator, do what plumbers do put heat tape around the regulator and piping? Put a gauge just before the appliance where it counts that would tell you the pressure from the secondary regulator. Why put a gauge at the house regulator that's probably covered with a shroud and you might have to trample thru the snow to read. I'm looking out the window at 6' of compacted snow, something I wouldn't want to do.

pecmsg

Now how deep is it buried?

Probably just below the surface. Not much thermal mass to retain the earths heat!

hot_rod

the water meter pits around here have a 2' thick foam pad pushed down against the yoke 3- 4' bury. Rarely do the meters freeze with just some insulation above.

But you would want to vent the regulator as the Propane 101 doc shows if you insulate over it.

I'd be leary to put an electric cable on a propane line, probably no power out there either?

vhauk

Any refrigerant’s pressure can be determined by the temperature of the vessel it is contained in. Propane is classified as a refrigerant, r-290. There is a direct correlation between temperature and pressure regardless of the liquid level as long as there is some liquid in the vessel. When propane gets close to -40 f the pressure in the tank will be very near 0 psig. A physical fact. A pressure regulator cannot do any good when there is no pressure. The frost on the outside of the regulator shows that the vapor temperature is below freezing. 

retiredmt

HomerJSmith said:

Why not just raise the temp around the regulator, do what plumbers do put heat tape around the regulator and piping? Put a gauge just before the appliance where it counts that would tell you the pressure from the secondary regulator. Why put a gauge at the house regulator that's probably covered with a shroud and you might have to trample thru the snow to read. I'm looking out the window at 6' of compacted snow, something I wouldn't want to do.

I'd like to put some type of gauge just before the boiler, but I'm told the pressure is less than 1psi and a pressure gauge won't measure that. Is there some other type of gauge I can have installed?

hot_rod

You buy a gauge that has a range of the pressure you want to measure. 11 inches is about what the second stage regulates to, so as suggested above, a few times:). Here is an example

The pic I showed a few posts up, had the 3 different pressure range gauges, tank, first stage, and second stage, 11”

My question would be what will you accomplish. If the gauge reads 0 you have a regulator problem

Or the lp tank is empty. Seems pretty obvious either the tank could not vaporize at that low temperature, or the reg froze up.

Is snow is settled on a copper tube, and it doesn’t melt, that tells you it is below freezing temperature, such as the pic of your regulator.

If there is any moisture in the reg and
Iit is below freezing, good chance it will not operate until it warms up.

Isn’t this exactly what you are experiencing. Changing the reg may well solve the problem if it has water or moisture inside.

If you keep doing what you are doing you’ll get the same result. You need to start with the obvious, a reg covered in frost

retiredmt

hot_rod said:

You buy a gauge that has a range of the pressure you want to measure. 11 inches is about what the second stage regulates to, so as suggested above, a few times:). Here is an example

The pic I showed a few posts up, had the 3 different pressure range gauges, tank, first stage, and second stage, 11”

My question would be what will you accomplish. If the gauge reads 0 you have a regulator problem

Or the lp tank is empty. Seems pretty obvious either the tank could not vaporize at that low temperature, or the reg froze up.

Is snow is settled on a copper tube, and it doesn’t melt, that tells you it is below freezing temperature, such as the pic of your regulator.

If there is any moisture in the reg and
Iit is below freezing, good chance it will not operate until it warms up.

Isn’t this exactly what you are experiencing. Changing the reg may well solve the problem if it has water or moisture inside.

If you keep doing what you are doing you’ll get the same result. You need to start with the obvious, a reg covered in frost

I agree with you 100% and you are indirectly answering the big question I had; "how can I tell that the problem I'm having is first related to a regulator issue?". If I could answer that, it might save me the hours of trying to troubleshoot the boiler. I get it, start at the obvious and that's what the gauge (and now your explanation of frost on the regulator) can tell me. My picture might have been misleading, only because when I lifted the lid to take a picture, a little bit of snow fell in. Otherwise it was clear and dry. But currently there is about 6' of snow on top of the ground where the buried tank is located, so I imagine that also helps insulate. Again, this is only happening in EXTREME cold. I'm curious what is your thought about pouring hot (or warm) water over the regulator if it is frozen? Is there any danger? Also thank for your insight, I appreciate the advice.

hot_rod

If it were me, I’d replace the first stage reg then build some sort of waterproof insulation over the opening. With the tank that deep, I believe the ground would keep that access chamber above 32
If you have good snow cover, I doubt the frost level is too deep, a couple feet? If the water mains around there are not freezing, that tells where the frost level is.

I’ve lived and worked in the Rockies for 30 years now, we put water lines 5-6’ deep, even under drives and roadways. Maybe that is why your tank is 6’ down.

I suspect there are above ground tanks around there also, how did they fare during that temperature?

Buy a couple outdoor thermometers and put one on top the tank, near the reg. Then insulate the cover and monitor the tank temperature with and without insulation. A thermometer above and below the insulation. Buy one with a lead on it so you can keep it above the foam to read.

Lumber yards and box stores sell 2” thick foam sheets, cut a few circles to push down over the reg. Install a vent tube as show a few posts above so the regulator can breathe below the insulation discs.

This maybe a $30 fix

The snow that sprinkled down would show signs of melting within a minute or so if that copper tube was above 32f. Did it?

vhauk

when when you buy propane it’s buy the gallon, because it is in liquid form. It’s under pressure in the delivery truck, to keep it liquid. It goes into your propane tank as a liquid. For your appliance to burn propane its must first become a gas. That involves lowering the pressure by venting the gas to your appliances. To become a gas the liquid propane must have heat to absorb to change state, liquid to gas. The pressure in the tank is determined by the temperature of the tank. Unless actively releasing or increasing the pressure. In very cold temperatures propane will have little or NO tank pressure. Testing your regulator will do no good unless there is pressure in the tank, which there won’t be at -35. 

pecmsg

vhauk said:

when when you buy propane it’s buy the gallon, because it is in liquid form. It’s under pressure in the delivery truck, to keep it liquid. It goes into your propane tank as a liquid. For your appliance to burn propane its must first become a gas. That involves lowering the pressure by venting the gas to your appliances. To become a gas the liquid propane must have heat to absorb to change state, liquid to gas. The pressure in the tank is determined by the temperature of the tank. Unless actively releasing or increasing the pressure. In very cold temperatures propane will have little or NO tank pressure. Testing your regulator will do no good unless there is pressure in the tank, which there won’t be at -35. 

Actually 3 PSIG

hot_rod

If that 6 foot deep tank at 70% with snow cover is freezing I’d be surprised. The riser tube where the reg is, maybe. A simple thermometer would tell the story.

Above ground tanks on residential loads work well below 0, mine did.

vhauk

yep, very low. But with temps that low, could the gas in the line condense. I missed that the tank is buried. (Sorry) In which case there should be plenty of pressure to the primary regulator. At -30 the pressure is less than 6 psi. 

hot_rod

I'm guessing a 500 gallon buried tank, at 70% fill it should easily vaporize enough for a small boiler load.
If you have multiple LP loads, maybe turn all but the boiler off and see if it stays running at those extreme lows. That rules out vaporization.

So you are left with a regulator issue. Cold weather LP guys claim the 6" regulators, the diameter of the diaphragm area, work better in sub zero conditions. Looks like your tank reg is a large?
4" is the smaller size.

You can look up soil temperatures here, compare to the pressure/ temperature chart @vhauk posted

https://www.weather.gov/ncrfc/LMI_SoilTemperatureDepthMaps

JUGHNE

It seems a good idea to add a shut off valve to any gauge inside the house.
You open the valve to view the pressure and then close.

hot_rod

gauge cock

EBEBRATT-Ed

There is nothing you can do at -38. The tank has no pressure in it so how can the regulators regulate something that is not there????

Commercial use propane fired vaporizers to keep the tank pressure up

Google: ALGAS:SDI they make all kinds of heating equipment to warm propane tanks

gas fired, electric, steam etc.

Zman

I think you are starting at the wrong end with your troubleshooting. I have seen above-ground tanks with huge loads that have dropped pressure on cold days, in that case, a vaporizer was needed. There is no way an underground residential tank is getting that cold. I would start by checking the pressure at the boiler with no appliances on and then again with the boiler at full fire and all appliances on. Most Lochinvar boilers have test ports on the boiler gas valve that you can connect to.

If your pressure is dropping below spec at the boiler, verify your pipe sizing and then have the propane company diagnose and swap their regulators. If it is stable, it's probably a boiler combustion issue.

https://www.supplyhouse.com/UEi-Test-Instruments-EM152-EM152-Dual-Differential-Digital-Manometer