Liquid Propane (LP) 101 - Regulator Staging

[Ampdraw]

I was reading through several posts under this section and thought I could provide some actual expert on this subject information that will elevate those who read it to almost expert level themselves. We'll start by just talking about regulators in this post, my goal is to eventually write additional posts to elevate everyone from "almost expert" to full blown card carrying certified experts. So sign up now and we'll later get into deeper subjects covering everything from setting up, adjusting and testing LP systems, natural to lp gas appliance conversion, altitude conversion and possibly so much more.

Why We Regulate Pressure

If you've heard the person fill your tanks at the end of the processes you can hear the very loud hiss from the propane being stored at very high pressure. This actual pressure will vary depending mostly on available space in the storage container and temperature, less empty space and higher temperatures will amount to higher pressures, possibly as high as 250psi. 250psi fed to the burner on your stove top would make it difficult to impossible for you to even light the burner, let alone do so safely. For your gas to actually burn it requires the perfect mixture or air/gas ratio and all the factors involved that affect this ratio. A sealed up room completely filled with LP and no air will not burn, if you've ever had the misfortune of witnessing an underground gas leak repair you'd probably be mind blown by seeing the guy down in the hole welding the metal gas line directly while the high pressure gas is shooting out of the leaking area he's directly welding on. He's able to do this because there's too much gas and not enough air to ignite and burn the gas. If that excited you then be disappointed now, I'm not going to cover how to weld leaking gas lines at any point and will tell you now, DO NOT attempt to weld your gas lines or tanks should they leak.

So with that basic understanding it should be obvious to you why we regulate our gas pressures from the high pressure in your tank (up to as much as 250psi) down to a usable level at our final destination that we end up measuring not in psi but in "inches of water column" or "WC (which is far less than even 1psi). This process is done in "stages" for a number of reasons you'll learn as we go here.

[Ampdraw]

That tiny LP regulator that came with your gas grill and its little short hose is NOT what I'm talking about, these are typically a "dual stage" or "two stage" LP regulator, it has both stages built into a single package, which is perfectly fine for that application where you have a short run (typically 4' or less) between the tank and the end use and are requiring a low BTU from the application. We won't be turning this topic into any kind of debate over what you use or see used and maybe even works. This is not a debateable subject, its an explanation on how to do things the actual right way or professional way and why its done this way. I could honestly care less about any opinion on how you do things, this is not a subject I need to be taught on, in most cases I don't even want to know because I wouldn't be able to sleep at night wondering if you're that guy who just pulled his RV into that slot next to me. Local building codes which vary all over the place must be followed or you'll be put in prison, possibly executed, or what ever they do in your area for violations.

The first stage regulator I have available for this instructional purpose is the red one pictured, if you'd like to buy one here's the actualy info:

Fisher
Type: R122H-AAJ
Inlet Pressure: 250psi
Inlet Threads: 1/4" FNPT
Outlet Pressure: 10PSI
Out Threads: 1/2" FNPT
Service Life: 20 years
https://www.emerson.com/en-us/catalog/fisher-r122h

We're going to split the stages between 2 seperate regulators in this tutorial to accomidate for longer than a 4' run from your tank to end use. Your first stage regulator needs to be installed at the LP tank, be it a very large tank measured in gallons, or smaller portable tanks measured in pounds of LP. Our goal is to drop the high 250psi tank pressure down to first stage regulation of about 10psi. For a permanent installation you'd want to run your gas lines from this regulator to the second stage out of actual pipe, my preference is 1/2" schedule 40 black iron pipe, threads sealed with both teflon tape, wraped in the right direction CW, and then a coating of pipe sealing paste on top of the teflon tape. Copper or brass pipe or tubing may also be acceptable if your local codes allow for it, some don't, I've never seen any that don't allow black iron. Copper or brass may also be found to be more suitable for underground or applications exposed directly to the elements since black iron is prone to rusting, they also make plastic piping rated for gas but I've never used it so will not be covering that subject. Flexable hoses rated specifically for LP gas and pressures are suitable for temporary applications. If using a hose, as I'd expect most people on an RV forum would be using, be sure to inspect your hose from end to end for signs of abrassions, wear or cracking and replace immediately, don't wait till it fails completely on you.

This is important!

The reason we install our first stage regulator as close to the supply tank as possible is not only because your hoses or lines are not rated for tank pressure, but more importantly because running high pressure LP through even a short hose directly attached to your tank is going to cause a thick oily goo to build up in the system and not only is it a smelly mess it will also plug up and ruin your hoses/lines, regulators and appliances. The longer the run from the tank to the first stage regulator the worse this phenomena will occur. THIS IS NOT DONE to make your leaks a low pressure instead of a high pressure leak as I've read in the comment sections of this forum, in many cases a low pressure leak would actually be worse than a high pressure leak, this is done to prevent the oily goo I just talked about from ruining everything. If your system is properly set up as I explain here and you later find this oily goo in everything after the first stage regulator then replace the regulator, its gone bad. You will likely also need to replace everything the oily goo has reached.

[Ampdraw]

Second Stage Regulator

As I already said, a two stage regulator is suitable for typically single application short run use, like tank, then two stage regulator, then less than 4' of hose, then BBQ grill (which is probably under 30,000 BTU). Attach the two stage regulator on the tank side of everything, not on the appliance side, or suffer the experience of the fore mentioned oily goo. If you are set up correctly and still find oily goo in the hose at your grill then replace the two stage regulator.

If you have a very large, high BTU, extra fancy grill, or like to cook at scientific level precision you'll probably find these cheap two stage regulators are not suitable. If you are running long runs from tank to end use you will probably find the cheap two in one two stage regulators unsuitable. If you are full timing or long staying at a single location in your RV and find the tiny built in/equipped LP tanks on your RV are unsuitable for people like me who don't enjoy unhooking and refilling tanks every 2 days, and want to add larger tanks then this separated stage regulator system I'm instructing you on is for you.

In my own application I like to use two 40 pound tanks, smaller tanks get used up too fast, larger tanks are to heavy when filled to muscle around and transport. Since 40 pound tanks typically (without modification) won't fit in the LP compartment on any RV I've owned you'll need to remote sit them out of your way or convenient to load for refilling. That means you're also going to be running gas lines probably further than 4'. This is where the first stage regulator we already talked about and the separate second stage regulator we're talking about now comes in. We put the first stage regulator directly on the tank, its set to lower tank pressure from 250psi to 10psi. I have a 20foot long 1/2" LP gas rated high pressure hose I attach 1 end to the out side of my first stage regulator, then the other end to the inlet side of my second stage regulator. The second stage regulator is then located as close as possible to end use.

The second stage regulator I have available for this instructional purpose is the green one pictured, if you'd like to buy one here's the actual info:

MEC
Type: MEGR-1622-BCF
Inlet Pressure: 10psi
Adjustable Outlet Pressure: 9-13 inches water column
Factory Preset Pressure: 11"WC
Inlet Threads: 1/2" FNPT
Outlet Threads: 1/2" FNPT
Service Life: 25 years
https://www.squibbtaylor.com/product...14427&cid=1305

The second stage regulator takes that 10psi pressure from the first stage regulator and gas line down to a useable pressure of 9 to 13 inches of water column. 1psi is equal to 27.708 inches of water column, so you can see our useable pressure is much lower than even a single PSI. The actual pressure your appliance requires will be located on the appliance data tag. The second stage regulator is adjustable to accommodate this, in most cases, it honestly isn't that critical and the preset factory regulation at 11"WC you'll find suitable. Fear not though, I'll get into explaining how to set gas pressure in another tutorial. Its simple to do when you know how and requires only a single, cheap, easy to use instrument called a Manometer (ma-nom-eter, or if you want to be silly man-o-meter). LP gas appliances typically run at 9-13"WC, Natural Gas appliances typically run at 3-5"WC. Too high of gas pressure will result in a very tall standing pilot light, possible problems with flame sensing safety devices like thermocouples, possible problems with electronic ignition, or inefficient burners with lifting blue flames. To low of gas pressure will result in the same problems but in the opposite direction. Correct gas pressure but too much secondary air mix will result in flames lifting off your burner (improper combustion). Correct gas pressure but too little secondary air mix is a bigger problem, it results in yellow tipped (not orange) flames. Yellow tipped flames will result in a messy, problematic, black sooty mess. On stove tops it makes the bottom of all your pans black, in systems like heaters and water heaters it will eventually plug up everything resulting in fires, explosions and more often death from carbon monoxide poisoning. Properly checking for these problems and correcting them will be covered in my upcoming gas pressure adjustment tutorial.

[Ampdraw]

I didn't proofread this, it took me long enough to think and write so ignore typos unless they're significant.

If you blow yourself up or burn anything down no one is responsible but you, please include pictures or video of you blowing up or burning so we can make fun of you for being an idiot.

[Ampdraw]

As I mentioned, I like running two 40 pound tanks. I connect them together at the tanks (very short run, high pressure rated line or pipe) and just before my first stage regulator. I keep the tank valve closed on the tank I'm not using that way I don't end up with both tanks going empty on me at the same time and I just manually close off the first tank when its empty and open the second. They do make switching valves you can use, you could even get crazy with it and run a 12VDC or 120VAC solenoid to remotely switch if you wanted to, but this is how you can do multiple tanks to a single first stage regulator.

Make sure you always open the valve on your LP tank all the way, not doing so could damage the tank valve or cause it to ice up and not work. Don't use a wrench to tighten the valve closed, if hand tight doesn't fully close the valve then you need to replace the tank. Closing it extra tight with a wrench just to be sure it's good and closed will end up ruining your valve and cost you more than the little bit of propane you thought you were saving from leaking out by having to buy a new tank after you ruin it.

Note, this is one we use where I work, not the actual one I use on my RV. I'm not the idiot who put Teflon tape on the tank fitting threads, but since I'm at work this was the one I had to take a picture of. The threads on that fitting do not seal and do not require Teflon tape or pipe dope on them. Your own fitting probably has a small o ring on the end of it, that's your sealing surface, not the threads on this type of fitting. Make sure your o ring is in good condition to avoid leaks.

[gasman6674]

Good Post
However a grill regulator is a single stage tank to burner regulator and is only legal on portable appliances like grills and hotplates. The regulators use on all Class C and Class A type units is an Integral twin stage. The automatic changeovers used on most other RV's also are Integral twins. Two stage systems are generally used on stationary systems that most of the time require higher capacity.

[Ampdraw]

Any portable grill I've ever bought came with a POS 2 stage regulator, which ends up in the garbage. The POS regulators RV manufacturers supply with their new RV's also immediately ends up in my garbage where it belongs.

There's a reason those regulators only have a 3-5 year service life and the ones I use are 20 -25 years.

[gasman6674]

Yep most of them are low bidder imports.

[gasman6674]

I had customers pull RegO regulators from service that were installed in the 50's.
I our industry's insurance usually mandates a regular change out period of 15-20 years.
Our regulators have a 25 year service life and a 10 year warranty

[djglover7]

Originally Posted by gasman6674

I had customers pull RegO regulators from service that were installed in the 50's.
I our industry's insurance usually mandates a regular change out period of 15-20 years.
Our regulators have a 25 year service life and a 10 year warranty

Can you provide info on your regulators?

[gasman6674]

I don't want to violate any forum rules on selling , But go to Engineered Controls International, LLC Manufacturer of Valves, Regulators and Accessories for Propane (LPG or LP-Gas), Liquid Natural Gas (LNG), Cryogenic and Compressed Industrial Gas.
And you should find the info you need if not let me know

[filthy-Beast]

Thanks for posting this.