PSI to BTU conversion

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AZdog
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2010/08/12 03:14:02 (permalink)

PSI to BTU conversion

I am currently running a 2 stage propane regulator for my set-up.  It gives me about 160,000BTU - however, I now need closer to 200,000BTU.

I have been looking at high pressure propane regulators (variable dial from 0psi to 30psi).

I don't have a clue as to what 1psi equates to in BTU.  I have tried to google it, but didn't have much luck.

Does anyone know what psi regulator I should be looking for to deliver around 200,000BTU?

Is there such a thing as having too much pressure?  For example, I get a 15psi regulator and only use 200k?

Both my griddle and my fryer have built in regulators, but recommend a regulator at the tank.
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    TrentonDog
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    Re:PSI to BTU conversion 2010/08/12 08:36:52 (permalink)
    Most propane equipment is designed to run at 10-11" WC (water column), which is just under .5 psi.
     
    To increase gas flow from 160K BTU to 200K BTU, you'd be going from a #28 orifice to a #22 orifice at the burner. No need to change the regulator as long as your current regulator can handle the flow. A two-stage should be fine. The problem is whether the air venturi can be opened up enough to provide enough air for the extra gas, and whether the burner will flow the extra fuel without burning back into the venturi. A 40K BTU increase is not trivial, the extra heat could damage/shorten the life of the burners even if it looks like everything is going well.
     
    I don't have any experience with high pressure regulators, but 15 psi of propane a lot of pressure. My limited experience with propane burners is from building a couple of custom teppanyaki grills and sizing burners for them.
     
    Hope this helps.
     
     
    #2
    Matt Gleason
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    Re:PSI to BTU conversion 2010/08/17 00:09:41 (permalink)
    Why do you need more gas flow?  Did you upgrade?
    If so, did you try operating your equipment with the existing tank regulator?
    Yes, there is such a thing as too much pressure and is the reason why manufacturers install regulators on their equipment.
    The reason for the regulator at the tank is so you are not relying solely on the equipment regulators.  You can install a larger capacity regulator at the tank however the regulators at the equipment will only allow their rated pressure through.

    You will also want to make sure that your new equipment came with propane orifices.
    #3
    AZdog
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    Re:PSI to BTU conversion 2010/08/19 02:54:53 (permalink)
    I got a number of suggestions and good information on this subject. Thanks guys.

    @Matt

    I have my griddle and deep fryer T-split off a single 40# tank with a 2 stage RV type regulator rated to 160k BTU.  I upgraded my griddle from a small 20" to a full 42" griddle.  The fryer uses 110k, and the griddle is rated at 3 x 30k. So, I am running about 40k less, and I can see it in my fryer as the recovery time is slower now.
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    Ice Cream Man
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    Re:PSI to BTU conversion 2010/08/19 06:58:54 (permalink)
    So you need to upgrade your Reg.
    You also need to make sure your propane line is big enough to carry the load. I haven't looked it up for a long time but you also might want to check and see if your 40 will vapourise fast enough for 200,000 at the temperatures you operate in.
    If you really don't understand gas and flow the best thing you could do is visit your local propane dealer.
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    Matt Gleason
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    Re:PSI to BTU conversion 2010/08/19 18:05:34 (permalink)
    AZdog

    I got a number of suggestions and good information on this subject. Thanks guys.

    @Matt

    I have my griddle and deep fryer T-split off a single 40# tank with a 2 stage RV type regulator rated to 160k BTU.  I upgraded my griddle from a small 20" to a full 42" griddle.  The fryer uses 110k, and the griddle is rated at 3 x 30k. So, I am running about 40k less, and I can see it in my fryer as the recovery time is slower now.


    Okay, the 42" grill will definetly need some more gas flow.  Glad to see you found the information you needed.
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    TrentonDog
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    Re:PSI to BTU conversion 2010/08/19 19:04:52 (permalink)
    Yep, you didn't need to bump up the pressure, just needed to increase the flow to maintain pressure under maximum flow. I thought you were trying to bump up heat output on existing burners to speed things up.

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    edwmax
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    Re:PSI to BTU conversion 2010/08/19 21:46:28 (permalink)
    I'm not sure why you need more BTU from the question.  .. I think you must have added more equipment, thus need more gas/BTU to supply the total BTU demand of ALL the equipment.    ... There is no conversion for PSI to BTU.  BTU is function of .... gas flow X's PSI X's (BTU/volume of gas).     Increasing the PSI will make the existing equipment operate more ineffecent and waste gas; and may not help at all.   .... What is needed is more gas flow not PSI.  Thus, a bigger supply line and tank to supply the quantity of gas require at the proper pressure.
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    AZdog
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    Re:PSI to BTU conversion 2010/08/19 22:36:16 (permalink)
    @edwmax

    What I am looking for is a larger regulator to allow more gas flow through - the problem that I have had is that most regulators don't indicate their max BTU output, but rather state their PSI rating.

    I am looking for a regulator with around 200k BTU flow through.

    @ICE

    Unfortunately my BB@ and propane shops around here don't sell anything with more than a 160k flow.

    Rego regulator  Looks like this one can handle 935,000 BTU - think it will do the trick.
    post edited by AZdog - 2010/08/19 22:54:35
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    Ice Cream Man
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    Re:PSI to BTU conversion 2010/08/19 22:53:39 (permalink)
    Any real propane dealer will have them, houses often run a 100,000 Btu furnace, 40,000 Btu stove, 30,000 Btu fire place, 30,000 Btu water heater, that's 200,000 with out including the gas drier, BBQ, or houses with two furnaces or the house with a big tub that has a 75,000 but water heater.
    You still have to have the right size pipe, measure the length and size, copper or steel. We can look it up for you. Or the propane dealer will do it when you buy the Reg.
    #10
    AZdog
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    Re:PSI to BTU conversion 2010/08/19 22:56:36 (permalink)
    It's black pipe, I believe that it is 1/4" pipe, and its about 10' long total with about 3 elbows in it.

    Edit: just measured it and it's actually a 3/4" pipe.
    post edited by AZdog - 2010/08/19 23:02:47
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    Ice Cream Man
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    Re:PSI to BTU conversion 2010/08/19 22:57:38 (permalink)
    I just typed in Propane Reg. and a million came up. Here's one.
    http://www.propanewarehouse.com/
    #12
    Ice Cream Man
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    Re:PSI to BTU conversion 2010/08/19 22:59:45 (permalink)
    AZdog

    It's black pipe, I believe that it is 1/4" pipe, and its about 10' long total with about 3 elbows in it.


    Go here. http://www.engineeringtoolbox.com/propane-gas-pipe-sizing-d_827.html
    #13
    AZdog
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    Re:PSI to BTU conversion 2010/08/19 23:04:27 (permalink)
    Ice Cream Man

    AZdog

    It's black pipe, I believe that it is 1/4" pipe, and its about 10' long total with about 3 elbows in it.


    Go here. http://www.engineeringtoolbox.com/propane-gas-pipe-sizing-d_827.html



    Nice, Excellent chart - looks like I'm right around 490k capacity.

    Thanks for the links.
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    Ice Cream Man
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    Re:PSI to BTU conversion 2010/08/19 23:11:39 (permalink)
    The other thing you need to know is what the recommended inlet pressure is for your appliances. It will be on the name plate of the unit or in the manual. Say it's 2 PSI. you then size your pipe and Reg to supply 2 PSI at over 200,000 BTU. some units are 14 inches. then the appliance Reg usually takes it down to 11 inches to run the burner.
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    Ice Cream Man
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    Re:PSI to BTU conversion 2010/08/19 23:14:20 (permalink)
    AZdog

    Ice Cream Man

    AZdog

    It's black pipe, I believe that it is 1/4" pipe, and its about 10' long total with about 3 elbows in it.


    Go here. http://www.engineeringtoolbox.com/propane-gas-pipe-sizing-d_827.html



    Nice, Excellent chart - looks like I'm right around 490k capacity.

    Thanks for the links.

    Not with 1/4 pipe unless you're running 100 psi, better check again.

    #16
    AZdog
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    Re:PSI to BTU conversion 2010/08/19 23:20:38 (permalink)
    Ice Cream Man

    AZdog

    Ice Cream Man

    AZdog

    It's black pipe, I believe that it is 1/4" pipe, and its about 10' long total with about 3 elbows in it.


    Go here. http://www.engineeringtoolbox.com/propane-gas-pipe-sizing-d_827.html



    Nice, Excellent chart - looks like I'm right around 490k capacity.

    Thanks for the links.

    Not with 1/4 pipe unless you're running 100 psi, better check again.


    I edited the post - actually went out and measured it at 3/4" .  The appliances don't indicate PSI, they just state a 11" L.P. W.C.
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    Ice Cream Man
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    Re:PSI to BTU conversion 2010/08/19 23:20:41 (permalink)
    What's the name plate on the unit say for inlet pressure?
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    Ice Cream Man
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    Re:PSI to BTU conversion 2010/08/19 23:25:57 (permalink)
    AZdog

    Ice Cream Man

    AZdog

    Ice Cream Man

    AZdog

    It's black pipe, I believe that it is 1/4" pipe, and its about 10' long total with about 3 elbows in it.


    Go here. http://www.engineeringtoolbox.com/propane-gas-pipe-sizing-d_827.html



    Nice, Excellent chart - looks like I'm right around 490k capacity.

    Thanks for the links.

    Not with 1/4 pipe unless you're running 100 psi, better check again.


    I edited the post - actually went out and measured it at 3/4" .  The appliances don't indicate PSI, they just state a 11" L.P. W.C.

    That's the manifold pressure after the appliance regulator.
    You need to know the supply pressure needed to the appliance regulator, it should be on the name plate, in the manual or on the appliance regulator. If you measured 3/4 inches the pipe is 1/2 inch nominal in side diameter.
    #19
    AZdog
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    Re:PSI to BTU conversion 2010/08/19 23:41:53 (permalink)


    That's a picture of my black pipe.

    This is a picture of the manf. plate:



    And here is a link to the fryer's spec sheet:  http://www.bestintown-equip.com/pdf/Royalran/RFS40.pdf

    Nowhere is a Psi stated, and the same scenario plays out for the griddle which is a Connerton.
    #20
    ardee
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    Re:PSI to BTU conversion 2010/08/20 00:47:52 (permalink)
    The picture looks like 1/2 inch pipe to me - the outside diameter of a 1/2 inch pipe (the accepted industry designation) is .840 inches.
     
    PSI is pounds per square inch, a measure of pressure - " W.C. is inches water column, another measure of pressure.  1" W.C. is equal to .0361 psi, so 11" W.C. is equivalent to .4 psi.
     
    BTU is British Thermal Units, a measure of heat energy - one BTU is the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.
     
    There is no conversion factor between PSI and BTU.
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    Ice Cream Man
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    Re:PSI to BTU conversion 2010/08/20 05:53:16 (permalink)
    Lets start from the beginning.
    1) You have a tank, the tank must be large enough to allow the propane enough time in the ambient temperature you operate in to turn from a liquid to a  vapour  for the BTU you want to use.
    2) You have pressure in your tank,  this pressure is unusable because it fluctuates with the ambient temperature. So we add a first stage regulator. The first stage regulator stabilizes the tank pressure and drops it to a usable pressure for the second stage regulator. The second stage regulator further stabilizes the pressure and drops the pressure to a usable pressure for the appliance regulator. You get better control with two regulators but the first and second stage regulators can be combined in one housing. On a BBQ you have both first and second stage regulators combined at the tank, on some there is no appliance regulator on others there is.
    3) The gas pipe, to size the gas pipe you need to know the pressure that will be in the pipe, the length of the pipe and the BTU that will be attached to the pipe. 
    There is a lot more to it than that but basically if you know these things you can size your tank, regulators and gas line.
    The best and easiest thing to do is go to a propane supplier and have them do it, it will take them 10 minutes if they can see it.
    By see it I mean the tank mount, the distance between the tank mount and the appliances and the appliance name plates.
    The reason they may be telling you their regs only go up to 160,000 could be that they are two stage regs, if they go above that they go to two regs, a first and a second stage.
    #22
    Ice Cream Man
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    Re:PSI to BTU conversion 2010/08/20 06:02:42 (permalink)
    Sorry I'm not making to much sense, after doing this kind of work for 35 years I put all this stuff away 5 years ago. Through out the books, sold stuff off and semi retired. It amazes me how fast we forget things we used to just do automatically. 
    #23
    edwmax
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    Re:PSI to BTU conversion 2010/08/20 08:39:35 (permalink)
    AZdog

    @edwmax

    What I am looking for is a larger regulator to allow more gas flow through - the problem that I have had is that most regulators don't indicate their max BTU output, but rather state their PSI rating.

    I am looking for a regulator with around 200k BTU flow through.

    @ICE

    Unfortunately my BB@ and propane shops around here don't sell anything with more than a 160k flow.

    Rego regulator  Looks like this one can handle 935,000 BTU - think it will do the trick.


    What you are looking for is a regulator with larger inlets & outlets.    ... The one you linked to has 3/4" dia outlet.  It should more than meet your needs.  The BTU capacity of the regulator is based on pipe size & internal orifice size, not PSI.  .... But, the questions now are, ..... can your tank supply the required gas flow ???? ... Is the gas piping from the tank & regulator to your trail manifold line 3/4 inch (or 1/2 inch)???? ..... Are there any pipe size restictions in the supply lines????

    Ice Cream Man's explanation is correct.  .... But what is not being understood is that as PSI is increased quantity of flow is decreased.  Thus accual BTUs being delivered decreases.   Also, increasing the PSI increase the back pressure on the tank, therefore, the amount of gas the tank can generate decreases.
    .....   This is no different than someone putting their thumb over the end of a water hose to increase the distance the water will squirt.    As the pressure increase the water will squirt a father distance, but the amount of water flowing out (BTUs in your case) decreases.

    ref:
    pipe size: http://home.mchsi.com/~gweidner/pipe-sizing-charts-lp.pdf
    LP Regulators: http://inspectapedia.com/plumbing/Gas_Cylinder_Regulators.htm
    Vaporization Rates of Cylinders (3rd chart down): [http://www.uscarburetion.com/lp_gas.htm[/url]


    post edited by edwmax - 2010/08/20 08:43:39
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