Natural Gas/ Low Pressure LPG Rig Possible?

[TXCrash]

Like the title says, I'd like some opinions on the feasibility of a convertible automated natural gas/ Low pressure lpg rig.

I'll be using banjo burners - I understand these have been successfully used with both natural gas and with low pressure propane using pilot lights, honeywell dual valves and thermocouples originally intended to be used with natural gas.

My understanding is that, past the low pressure lpg regulator (which could be connected via quick connect) the only difference between a low pressure lpg rig is the orifice size in the burner and in the pilot light.

Where I'm stuck in my thought process is how do I quickly and easily swap out orifices? Is it even possible?

I want a convertible system because I want to be able to brew at a friends house, yet I have nat gas at home - no more inconvenient propane refills before brewdays at home.

 

[day_trippr]

Can't speak for all burners, but the orifices on my big banjo burners are simply brass threaded inserts to the venturi bell and easily changeable...

Cheers!

 

[TXCrash]

Can't speak for all burners, but the orifices on my big banjo burners are simply brass threaded inserts to the venturi bell and easily changeable...

Cheers!

My experience with brass in steel is that after a number of firings, you'd be hard pressed to unthread the orifice without mangling it. Also, that still leaves the orifice in the pilot - which in most installations appears it'd be hard to get to. Pilots are cheap - maybe 2 pilots per burner and valves to choose which one?

I'm a gas dummy - I'd like someone to tell me this will or will not work.

 

[OneHoppyGuy]

My experience with brass in steel is that after a number of firings, you'd be hard pressed to unthread the orifice without mangling it. Also, that still leaves the orifice in the pilot - which in most installations appears it'd be hard to get to. Pilots are cheap - maybe 2 pilots per burner and valves to choose which one?

I'm a gas dummy - I'd like someone to tell me this will or will not work.

To prevent seizing, use an anti-seize. It's an aluminum paste used in automotive and industrial applications. I use it for water pump, exhaust and spark plugs.
Here is one brand: http://www.permatex.com/products/au...ubricants/Permatex_Anti-Seize_Lubricant_a.htm

 

[VladOfTrub]

Like everyone mentioned, you'll need to change orifices when changing fuels. You mentioned Honeywell gas valves. Common Honeywell valves come from the factory to use NG. Inside the box is the LP conversion kit. Their pilot assemblies come with both orifices. Honeywell valves are factory set at 3.5 inches water column (WC). If you decide to use the Honeywell 24 volt standing pilot gas valve and go from NG to LP, you will need to remove the NG regulator spring and install the LP kit. Once you do that, the valve outlet pressure will change. Without a manometer you'll never know where to set the regulator pressure. There is a port on the side of the valve to attach a manometer, to measure outlet pressure. If you decide on using a gas valve you will need to decide on what type you'll need. Snap opening or slow opening type. Then you'll need to decide what operator and power supply you'll need. I've converted my Blichman burners to NG and automatic gas valves. I installed the valves underneath my brewing platform to protect them from water damage. I use Honeywell aquastats and an Argo controller to fire the burners and start the pumps. I used Blichmans NG burner orifices... Good Luck. Don't burn down your house or blow your a$$ up.

 

[JuanMoore]

I forgot about the spring and screwcap swap required in the valve. Without two separate valves I'm not sure how feasible swapping back and forth between NG and LP really is. Not something I'd want to do regularly. FWIW the conversion kits come with instructions on how to set the valve pressure close enough without a manometer. A manometer makes for a more accurate pressure setting, but it's not entirely neccessary, especially for our purposes.

 

[TXCrash]

Two separate valves would kill the economic feasibility of the build. Crap.

That's why I posted this thread though. Back to the drawing board!

 

[VladOfTrub]

TX: Stay with your idea. It is do-able, if you want to spend the Shecles to do it.... This how I'd build your idea: On the end of your burner you have the plate that the orifice threads into. The plate is called the atmospheric balancer. It has openings cut into it that can be closed or opened to adjust the air/fuel ratio. Remove the atmospheric plate/orifice holder located at the burner inlet and increase the diameter of the hole that the orifice threads into, to accept a 3 X 1/2 NPT black pipe nipple. Use (2) lock nuts to hold the nipple to the plate. Attach the other end of the nipple to the "tap" of a 1/2 inch black tee, using LP approved pipe dope. Re-attach the plate to the burner. The tee should be running horizontally. Procure (2) 1/2MPT X 1/4FPT bushings. Drill out the 1/4" opening in the bushing and tap to accept the LP and the NG orifices. The orifices are a standard ASE thread. Thread both bushings holding each orifice into the "run" of the tee. Procure (2) Honeywell, Robertshaw or White Rogers 24 volt, slow opening, standing pilot valves, 2 thermocouples and 2 pilot assemblies. Convert one valve and one pilot assy. to LP. Keep the other valve and pilot assy. NG. Connect each valve to their orifice. Tie the gas inlets of both valves to a common header. Install both pilot assemblies to the burner. Insuring that the burner flame doesn't impinge on the thermocouple, and located in an area that fires the burner without flame rollout or delayed ignition. Procure a manometer to adjust both valves for the CFH of the burner. Adjust the pilot flame using the device located on the valve. Someone said that the instructions that comes with the valve tell how to adjust the regulator valve to be "close enough" and that's good enough for homebrewing. What the guy may not realize is that valve manufacturers design the valves to be installed into devices (furnaces and boilers) that are AGA approved and that have every safety feature known to man built into them. Not into Turkey cookers. So "close enough" in a fire breather Banjo can go bango. Once the pipe fitting is done. Design control circuits.

 

[kladue]

Wow, this is interesting, moving the orifice fitting away from the burner air mixer plate will not work, the high speed gas flow from the orifice is what induces the air flow.
As to the rest of the information offered, go to the other threads with successful builds using the Honeywell VR 8200 standing pilot valves and Q314 pilot burners on both NG and propane. Or look at the electric ignition systems using the honeywell S8610U ignition controller and 24VAC solenoids with Q345 pilot burner.
Trying to use the NG burner orifice with propane at lower pressure does not work, higher density propane needs more velocity to pull enough air to mix properly, higher pressure and smaller jet are a must have.
With a couple decades of experience working with gas from pipeline to appliance, I have learned a few things along the way.

 

[TXCrash]

Kevin,
Do you foresee a reasonable way to do this which would require a 20 minute or less changeover process each time I switched fuels?

 

[kladue]

Switch burner orifices and switch VR8200 regulator springs, leave pilot orifice br 18 (.018") for NG (burns white/yellow but still hot enough). With conversion valves from williams brewing, never sieze on threads of orifices, and careful attention to re-tightening all connections(make a numbered check list), you should be able to switch in a reasonable time frame. One method of VR gas regulator setup is to open down stream flame adjustment valve wide open, and with regulator spring backed all the way off, turn spring adjuster in until max flame level is reached( about 4-6"), then flame adjustment with down stream valve is easier. With some appliances and manufacturers, a specified pressure is called for, but the banjo burner on low pressure is anything but standard application, and adjusting internal regulator for max fire level applies.
A small spray bottle and kiddies bottled bubble solution will be your best friend when testing connections, the bubble mix will find the smallest leaks and grow a beard, and spray bottle will hit almost everywhere.

 

[cutter22]

I have a similar issue/question related to this thread.

I have setup a HERMS with a VR8200 and an Auber PID which is all connected to a Blichmann burner. I was running it on NG for a year or so with no problems at all. I recently moved to a new location without NG availability so now im running on LP. Ive switch all necessary orifices and springs over for LP.

The issue im having is that its not a powerful flame and the flame pulses (moves up and down). The only thing i can think of is that the problem lies in the VR8200 side. I have troubleshooted with the same high pressure regulator provided by Blichmann and another Blichmann burner (without a gas control valve) and all works well.

Any suggestions would be much appreciated.

 

[JuanMoore]

Have you tried adjusting the regulator pressure in the VR8200 using the method kladue mentioned above?

 

[cutter22]

Yes i have tried a few things.

I tried the adjustment stated above. Backed the spring all the way out and worked it in. No luck, the flame is really small, it doesnt like to get to a powerful level which will take a long time to heat the HLT.

What ive noticed is actually the gas valve switching on and off which creates the pulse. I assume the pressure coming from the high pressure regulator (which comes with the blichmann) is too much for the gas regulator even with the screw/spring backed out.

I have tried using a low pressure regulator from a bbq and everything works without pulsing. But then again the flame is really small and will take forever to get my HLT up to temp.

Going to try a few more options, any suggestions again super appreciated. Trying to brew tomorrow!!!!

 

[kladue]

Whoa, the high pressure regulator is the problem, at the pressure setting low enough to operate the valve it struggles to hold pressure steady as the setting would be at or below normal use point. Retire the high pressure regulator and buy a 2 stage low pressure regulator which is stable at almost any flow level from low to high. A Marshall 290 would be a good choice as the burner running low pressure LP is only using 70K maximum, and over 50K the flames are up the sides anyway. Other single stage tank to low pressure will work but they are not as stable when you are running a low flame level.
The BBQ regulator is usually only rated for about 35K, sometimes even less as most feed BBQ's with smaller burner loads than that, that is why you need a Marshall 290 that can handle 160K to feed two burners at high fire levels

 

[cutter22]

Thanks kladue!
I'll look into the dual regulator. I did something in the meantime which seems to work. I used a spring from a retractable ballpoint pen and placed it in the center of the LP spring of the valve. It's a bit stiffer then the provided spring. With a little tuning it worked. Don't know if this could damage the valve but it seems to work fine.

Would a dual regulator provide less btu's than this current setup? This seems to be giving the needed power.

 

[kladue]

The second spring is not the best idea as these valves are meant for low pressure and should work well with 11-13" inlet pressure. The 2 stage regulators are common to the RV propane systems so you should be able to find one easily, and they work well with one or two burners operating at same time.
If you have the low pressure orifice installed in the burner then you should have plenty of fire when using low pressure propane.

 

[cutter22]

thanks again kladue
ill give this rig a go today since im brewing with the second spring and then get a 2 stage reg for the future brews. appreciate all the help.
cheers