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 LP Lines

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The GCS

  • Total Posts: 14
  • Joined: 2/10/2012
  • Location: Indianapolis, IN
LP Lines Sun, 02/12/12 1:43 PM (permalink)
First off, thanks for all of the info you all have posted on here! It's great to be able to research food truck specific things that have helped in my build. I've seen a lot of things on LP lines and regulators. It seems like the info is there, somewhere. It's hard to piece everything together to get answers to my questions.  
  
I have two 40lb cylinders that I will be powering a 36" Vollrath flat grill, a two burner stove top, and an Ecotemp L5 water heater. The kitchen area of the truck is 11 feet long and the cylinders are in the back driver side. The grill and stove top are on the driver side, towards the back, and the water heater is in the front passenger corner. I have an auto-crossover regulator at the tank and a regulator that came with the grill. The inlets for the grill and the stove top are 3/4" and the out for the regulator is 3/8". 
  
For the pipe, I've seen everything from 3/8" to 3/4". What size should I use? Is 1/2 ok? Do I run a constant main size and then tee off to each appliance with the flex line and a shut-off valve? Do I need to use the grill regulator also or is the regulator at the tank sufficient? For the length of the main I'm going to run it to the divider wall, up to the ceiling, over the door, and down to the water heater(since I've seen length makes a difference).  
  
Thanks in advance and for all the help so far!
 
#1
    Dr of BBQ

    • Total Posts: 3716
    • Joined: 10/11/2004
    • Location: Springfield, IL
    • Roadfood Insider
    Re:LP Lines Sun, 02/12/12 2:16 PM (permalink)
    Consider this http://www.ebay.com/itm/1...ksid=p3984.m1438.l2649
     
    But if your lines are too small it will effect your appliances dramatically. I would check for the BTUs on each appliance and do an internet search to find the correct size.
    <message edited by Dr of BBQ on Sun, 02/12/12 2:18 PM>
     
    #2
      The GCS

      • Total Posts: 14
      • Joined: 2/10/2012
      • Location: Indianapolis, IN
      Re:LP Lines Sun, 02/12/12 2:26 PM (permalink)
      Awesome. There is some at my local Lowes so I'm gonna go check it out to see it in person. I could run this from the cylinders to the appliances, just add shut-off valves and adapters? Any ideas on the regulator question?
       
      #3
        Vic Cardenas

        • Total Posts: 177
        • Joined: 2/9/2012
        • Location: Midvale, UT
        Re:LP Lines Sun, 02/12/12 2:26 PM (permalink)
        Not sure if it helps you or not, but my truck is all originally 1/2" piping, to a flat top, steam table, fryer, coffee warmer, and oven. It comes from a 1/2" regulator outlet and just tee's off to everything in 1/2".  All the appliances are un-regulated. Only the two-stage at the tank. 
         
        If I were you I'd try and get a regulator with either a 1/2" or 3/4" outlet. You may not make enough pressure from the reverse bottleneck of the 3/8 regulator.
        <message edited by Vic Cardenas on Sun, 02/12/12 2:28 PM>
         
        #4
          The GCS

          • Total Posts: 14
          • Joined: 2/10/2012
          • Location: Indianapolis, IN
          Re:LP Lines Sun, 02/12/12 2:28 PM (permalink)
          Thanks Vic. Should the regulator at the cylinders be ok if it's rated at a high enough BTU for my appliances or do I still need to use the one that came with the grill, at the grill?
           
          #5
            Vic Cardenas

            • Total Posts: 177
            • Joined: 2/9/2012
            • Location: Midvale, UT
            Re:LP Lines Sun, 02/12/12 2:29 PM (permalink)
            Sorry, I ninja-edited while you were typing.
             
            #6
              Blissful Bite

              • Total Posts: 55
              • Joined: 12/18/2010
              • Location: Lawrence/KC area, KS
              Re:LP Lines Sun, 02/12/12 6:41 PM (permalink)
              The regulator at the tank provides 11 inches of water column pressure for propane (4" w.c. for NG) in your pipes.  If your pipes are too small for your demand, you deplete the pressure faster than the regulator can re-supply.  Another regulator at the appliance doesn't actually do anything.  
               
              What's the largest inlet for your appliances?  Your whole system should probably match that.  There are definitely some good links to pipe sizing calculations on the forum somewhere...
               
              I have a high output regulator rated for 300K btu/hr that I bought from an lp supplier in my area. The output side is 3/8".  I increase to 3/4" right away.  
               
              The flex line is probably pretty nice to work with versus black iron pipe...once you pay 3x + more for the line, special fittings, and special tools.
               
               
               
              #7
                edwmax

                • Total Posts: 2015
                • Joined: 1/1/2007
                • Location: Cairo, GA
                Re:LP Lines Sun, 02/12/12 7:31 PM (permalink)
                This link will help. http://home.mchsi.com/~gweidner/pipe-sizing-charts-lp.pdf
                 
                I think you would want to run the main supply pipe at 1/2" or 3/4". Then reduce to down to 1/2" or 3/8" flex at the tap-off to connect the equipment.   This would help to keep the gas flow even to all piece of equipment.   If one appliance should draw enough gas to effect the operation of a down-line piece, then it would be easy to install a double regulator setup (high/low) without having to re-pipe the system.
                 
                20ft of 1/2 pipe will supply aprox. 200,000 BTU at 11" WC; 3/4" pipe approx. 416,000 BTU.   ...What is the BTU rating of each piece of equipment?
                 
                #8
                  The GCS

                  • Total Posts: 14
                  • Joined: 2/10/2012
                  • Location: Indianapolis, IN
                  Re:LP Lines Sun, 02/12/12 7:33 PM (permalink)
                  Thanks Bliss. The biggest inlets are 3/4" on two appliances. I'm not going to be running the grill wide open and the stove top will only be on low to occasional medium power. I went ahead and went with 1/2" flex pipe that I went and got today after looking around. I hope this purchase of pipe and fittings wasn't too premature.....
                   
                  #9
                    The GCS

                    • Total Posts: 14
                    • Joined: 2/10/2012
                    • Location: Indianapolis, IN
                    Re:LP Lines Sun, 02/12/12 7:35 PM (permalink)
                    I have a 26000 BTU stove top and 28000 BTU grill. On the back of the grill it says 28000 BTU per hour on the tag but the manual states that its an 80000 BTU output per hour. That somewhat confused me.
                     
                    #10
                      THE WILD DOG

                      • Total Posts: 1465
                      • Joined: 1/12/2010
                      • Location: Hunt Valley, MD
                      Re:LP Lines Sun, 02/12/12 8:08 PM (permalink)
                      with building a food trailer and a food truck, I went with 3/4 black iron as my main lines. I don't suggest going with 1/2 b/c once you've put it in, you're not gonna be happy with pulling it out and replacing it if need be. I suggest running the mains at 3/4. Most if not all regulators are 3/8, you can get a step down from 3/4 to 3/8. The pressure will build up and maintain it'self. I've not ever had one single problem with 3/4. I've experienced low pressure due to a built in regulator on a piece of equipment and had no choice but to have a regulator at the tank end. You don't want that headache.
                       
                      #11
                        edwmax

                        • Total Posts: 2015
                        • Joined: 1/1/2007
                        • Location: Cairo, GA
                        Re:LP Lines Mon, 02/13/12 9:03 AM (permalink)
                        The GCS


                        I have a 26000 BTU stove top and 28000 BTU grill. On the back of the grill it says 28000 BTU per hour on the tag but the manual states that its an 80000 BTU output per hour. That somewhat confused me.

                         
                        The 80,000 BTU should be the max. heat out-put of all burners.   Then-if, each burner is 26,000 BTU, your grill has 3 burners.    The tag on the back gives the rating of each burner.      ... Using a 3/4" main line then reducing to a short 1/2" flex connection at the grill, there should not be any problem for gas supply to the grill.

                        I believe your problem will from the tank size.  A 40 lb DOT cylinder @ 60 deg F will only supply aprox. 40,100 BTU (vapor per hour), which is 1/2 of the rating of the grill.   You will need to have both tanks on and most likely warp the tanks with heat blankets when the outside temp. is below 70 deg F.
                         
                        You probably need to consider using two 100lb cylinders & both tanks on.   ...  @ 60 deg F = 79,400 BTU  & @ 30 deg F => 52,400 BTU   ... Again use with heat blankets at low temperatures.

                         
                         
                        <message edited by edwmax on Mon, 02/13/12 9:13 AM>
                         
                        #12
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