frozen gas regulator

Herb

On a new install, I presume the customer installed a new underground LP tank. Since the service boy didn't find the frozen reg it's probable that company didn't service the tank properly prior to putting it in service. That tank should have had a gallon of methanol injected and any air in the tank purged by means of LP vapor. Anyway, there is water vapor in the gas now and it needs to be neutralized. Have the LP company return, replace both regulators and inject methanol into the tank.

molly

frozen gas regulator

We're oil folk but have recently installed an lp Munchkin for a customer that requested gas. What a thing of beauty! It has been up and running FLAWLESSLY for about 4 weeks. It's a radiant injection system with about 6000' of tubing. The building is still under construction (no insulation) so it's been running pretty much non stop. Been circulating about 90-100 degree water. Today, the boiler locked out on code 4, which means flame failure. We had the gas company's service man come out to check it out. Remember, we're oil folk. They checked the gas pressure inside and told us the problem was with our equipment. NOT A GAS SUPPY problem. The tank is a large burried tank (500gal?). The gas service man didn't know how to work on the burner or diagnose the Munchkin so he left. After a call to HTP, very quick response by these folks, we checked to make sure the gas reg was not frozen. Much to our relief and frustration (due to wasted time trying to trouble shoot an equipment problem) we found out it was indeed frozen. My question, finally.... Why do regs freeze up? The temp has been in the lower 20's, then went to upper 30's/low 40's and there was a gas delivery today. It's now again mid 20's. Is there a conection to the weather temp? The tank being recently filled? Anything to do with the tank running nearly enmpty the day before? Not trying to take the gas world by storm, just curious.

Don_4

regulator problem

Without all the details on the piping and gas system I cannot give a definite answer. I suspect the gas regulator may be allright but the constant use may have caused the freeze up. When the gas is passed through an orifice and is changing state (liquid in the tank to vapor in the gas line)it absorbs a lot of heat. Even the change in presure can contribute to this. This could have caused the freeze up. Just for info sake propane can be carried in a bucket at -45 deg F. If the regulator was sized for significantly more load than is currently on the line this would also contribute to the problem.

Unknown

Right on Herb

Also if the tank started to run low the existing methanol which should be installed at this time of year may have run low.

LP gas becomes a problem when the temperatures start to drop down into the 20's.

Another thing that helps is to have some steady 24/7 flow of gas such as a pilot on a water heater, when the gas sits and does not move and then a sudden demand (call for heat) it will cause it to freeze up.

munchkin-man

Propane is in liquid state around -100 45 degrees

the liquid propane must be compressed at around 105 psi so it can be coverted to vapor gas. The use of a 2 stage regulator when delivering over 40,000 btu's is critical because the first stage regulator must bring down the pressure so it can change to gas vapor, the second stage regulator regulates the pressure to the appliance. In your case you only had a 1 stage reg, that is like opening a 20 lb propane tank wide open with no regulator the liquid propane stays in liquid form and comes flying out like water from a hose, if you were to turn down the valve and slow the pressure from escaping to fast it will turn to gas vapor. The regulators work the same way. There is a temp ratio that is in a range from 33* to 45* and the humidity and the dew that can cause condensation in the reg. The propane is at -40 or so so the liquid propane froze the condensate deposits in the reg. The condensate gets in through the vent on the regulator. Thats it in a nut shell. hi steve in canada

molly

factory purged?????

When the G.C. asked the gas co about pre purging the tank in the manner you've described, their reply was, "We don't do that anymore. It's done at the factory." Sounds pretty iffiy to me. We went to the gas co office this morning to tell them what we found. Their response was less than encouraging. We asked them to do what ever needed to be done. We're at their mercy. It's their tank, their install, they sized the regulator(s). They seem unwilling to educate us on what is going on. That's why I'm here. Thanks to you guys I'm getting some good advise.

molly

how do you know if it's 1stage or 2 reg?

First off, thanks for the quick response. I love sharing knowledge. How do I know if it's a 1 or 2 stage reg? There was 1 under the cover of the underground tank(this was the one covered in frost) and there is one mounted on the side of the house. The gas co sized the reg(s) and the outside gas line. The inside line is 1" b.i.. The outside buried line is 1/2"c(installed by gas co). The load on the system so far is 140,00 btu. I'm pretty sure they didn't pre purge the tank upon installation last month. Is there anyway to tell if they did or didn't do this? They gas co is unwilling to share information with anyone. Thanks for any info.

gasser9

frozen gas regulator

All of the new tanke i have heard of are shipped with compressed air in them. If you do not purge the air & somtimes water out you WILL HAVE TROUBLE!!!!!! ie; air
lpg mix lowering btu content a lot also unusual pressures
(remember lpg is a referigerant very similar to r12) add air & water to r12 or r22 it will freeze at the metering device (regulator).
Your lp supplier should pump OUT the tank and properly purge the tank either by pulling at least 15" vacuum or
by filling the tank & evacuating 15psig VAPOR ONLY!!!
IF THEY USE LIQUID ALL THEY WILL DO IS CONDENSE & FREEZE
THE WATER THEY LEFT IN IT THE FIRST TIME!! A 500 gal lpg tank will need to have at least 1 quart of pure anhydrous METHONOL NOT ETHONOL or 2 qt of air brake dryer added. The 500 gal underground will vaporize about 750,000 btu/hr.
If the vents on the regulators are angled down the only place the water(ice) can be is inside!!
frost on the outside will indicate a restriction-- first regulator frosting=h2o in tank second reg frosting=h2o in
line! referigeration
30 year lpg veteran -40deg - 115degf

molly

thank you gaser9

Any and all knowledge is very much appreciated!!! I just wish I had some control over rectifying this. It seems as though it's up to the gas co to make good. Thanks to all who have and may yet reply.

gasser9

Just a ps lpg is always sent to smaller loads (1,000.000, btu or less therabouts) fron the tank as a vapor from the top of the tank. if the tank was over filled ie 90% from the truck @ 20 deg the ground temp could warm it to 100% BIG PROBLEMS!! 264% + PRESSURE INCREASE===TOO MUCH GAS &
CONTAMINAITED CONTROLLS FROM TANK TO BURNER!
the REGO.COM site has a neat little SERVICEMANS MANUAL available free & a lot of LPG info.
any help I can give have my add

Jeff_8

frozen gas regulator

Many new LP tanks are now vacumn purged at the factory. It is standard procedure to put methanol in the tank before it is put in the field. Before it is filled with liquid, it should be pressurized with vapor first. This method is much easier and faster than doing tanks that are pressurized with air. I also wish to explain about first and second stage regulators. Most Gas units burn vapor which is drawn off the top of the lp cylander. The first stage regulator reduces tank pressure to approximately 10 PSI. The second stage regulator then reduces the pressure further to an operating pressure of 11" water column. This can be done with using seperate first and second stage regulators or with using an itegral two-stage regulator. A two-stage regulator basically does both functions. The most common causes of regulator freeze ups are either moisture in the gas or moisture getting into the vent of a regulator and not allowing the diaphram to move up and down.
I have been an LP gas technition for 15 years and have recently started doing oil service also. I hope this clears up some things for you.

kevin_5

Another slightly different problem.

Actually this happened a few years ago. I had shut off a residential natural gas meter to reroute some lines inside, and when we turned it back on- no gas. We gently tapped on the meter, and heard it start spinning as the line packed. They never had any more problem. As I remember, it wasn't down to freezing, and I never understood exactly what happened. I have a small radiant home on natural gas, and the delivery/surcharges are about as much as the actual gas I use. Propane is starting to look pretty good to me. My grandfather used to have oil, but I can't think of anyone who has it now. Nebraska is flat enough and easy trenching enough (few rocks) that there are a lot of rural gas lines; high use farmers make it worthwhile with their irrigation wells and grain drying bins. Lots of LP too. Kevin

Steve Ebels

What probably happened

A lot of gas meters have a safety lockout on them that stops flow if the rate exceeds a predetermined amount. When you opened the valve on the meter it probably whooshed into the pipe and then stopped due to the fact nothing was calling for gas at that time. The sudden flow and then stop will lock a meter up sometimes. I have had a couple do this to me. I had to shut off the valve, undo the union on the inlet side of the meter to relieve the pressure and reconnect. This allows the pressure in the inlet side of the meter/regulator to escape and the meter will unlock. Never heard of one that unlocked by tapping on it but anything is possible. Best to open that inlet valve just a crack and allow pressure to equalize before going full open.

Unknown

Turning on gas (Natural)

at any time TURN IT ON VERY SLOWLY TO PREVENT LOCK UP. As you turn the cock you will hear a little "whooshing" sound once you hear that go ahead and turn it on full.

Dave_8

Freezeup

I have to concur with most of this, if you have freezeup on the primary regulator it is almost always due to water in the fuel supply. One point that concerns me is that I have never seen an underground tank that was "owned" by a gas supplier. They will sell you these tanks but almost never lease them because they would not be able to "reposess" the tank. I would check out this point carefully! Our next response would be "if you cannot get us good fuel pull your tank and we will find someone that will". As the LP industry in very competitive that will always get you an immediate cure to the problem.

We work with LP about 65% of the jobs we do and the suppliers are mostly pleased to help with any problem we have as they know that the competition is waiting in the wings for any screwup. We have forced the issue on poor fuel quality twice this season already (once on LP and once on fuel oil). If nothing else, remind them that if the house freezes up and the fuel is found to be contaminated they are liable for any repair and cleanup!

kevin_5

Thanks Steve and Timmie

I appreciate the information on the gas meters. I don't know who first told me to turn the gas on slowly, but it sure sticks in your brain better when you know WHY! I had no idea.
Isn't is amazing that through the medium of internet, people can help each other and have such an impact on lives. I consider this place my continuing education.
Thanks again, Kevin