Food Truck Propane Issue

[SheaSmith]

Hello,
I have a food truck that has two fryers, two flat top griddles and a water heater in it. All the equipment is non-commercial (originally set up for 20lb tank use). We figured that all the units run on different pressures so we ran high pressure propane line into the truck and have individual regulators at each cooking unit. (I know that it’s not by the book). The propane line is 1/2 inch black iron, and we have it hooked up to two 30lb tanks. We figured that 1/2 inch of high pressure propane would be plenty to power our stuff (about 300,000 btu at any given time) but we have issues. Sometimes the units get enough power and sometimes they don’t. We are trying to figure out what our issue is. Obviously we have enough flow potential since the little high pressure-pigtails that usually come before full-system regulators are tiny. Any ideas?

 

[Twowaxhack]

You probably don’t have any trouble when both tanks are full.

As the tanks draw down the pressure probably drops.

My answer is get bigger tanks or don’t use everything at once.

 

[SheaSmith]

You probably don’t have any trouble when both tanks are full.

As the tanks draw down the pressure probably drops.

My answer is get bigger tanks or don’t use everything at once.

We have the issue when both tanks are full

 

[Twowaxhack]

Your tanks are too small.

http://www.nbmc.com/heaters/lpchart.html

 

[Twowaxhack]

https://www.propanewarehouse.com/helpful-information/lp-gas-properties/

 

[SheaSmith]

Your tanks are too small.

http://www.nbmc.com/heaters/lpchart.html

So according to that I’d need 13 30lb tanks?

 

[wpns]

So according to that I’d need 13 30lb tanks?

What’s your temperature? Do the tanks feel cold when you are experiencing issues?

 

[SheaSmith]

What’s your temperature? Do the tanks feel cold when you are experiencing issues?

I’ll need to check that

 

[wpns]

So according to that I’d need 13 30lb tanks?

To be fair a normal backyard barbecue is maybe 50,000 BTUs, and they use 20 pound tanks, and you’ve got (first approximation) three times that, but you need six times that.

But again, it depends on your temperature, just look at the chart, you’re going to get a lot more out of those tanks at 70° than you are at 0° #QuellSurprise

 

[havasu]

I myself would look at other running food trucks, and checking how they plumbed this all together. I am sure they aren't running (13) 30 gallon propane tanks.

 

[Twowaxhack]

I’d get a couple 100 gal tanks. Or dedicate smaller tanks for each appliance.

Try to keep your tanks warm.

 

[SheaSmith]

To be fair a normal backyard barbecue is maybe 50,000 BTUs, and they use 20 pound tanks, and you’ve got (first approximation) three times that, but you need six times that.

But again, it depends on your temperature, just look at the chart, you’re going to get a lot more out of those tanks at 70° than you are at 0° #QuellSurprise

We’ve had the issue at 70 degrees

 

[wpns]

Is it worse when it’s windy? I gave up on a propane cooktop because everytime the wind would blow or the ceiling fans were running it’d blow the flame around and it’d take 1/2 hour to boil water for pasta.

Not that our solution (induction) would work for a food truck but could point to a potential problem.

Can you put a pressure guage on your ‘high pressure’ line? Amazon.com : propane pressure gauge has lots of options that attatch to tanks.