5 lb vs. 10 lb first stage propane

archibald tuttle

First stage regulators for bulk propane tanks are nominally targeted by most manufacturers at either 5 lbs. or 10 lbs (although adjustable around or below those ranges depending on the manufacturer). But all the BTU ratings I can find for the second stage regulator presume 10 lbs. inlet. I did find one manufactuer (Rego) that specifies secondary regulator capacity using an assumption of 10 lbs inlet, but included some performance curves relating inlet pressures between 5 and 12 lbs to outlet pressures between 9 and 12" WC.



Extrapolating from that it seems that my current application could be served by 5 lbs. although it would not leave a lot of capacity cushion on the secondary regulatory for any future propane appliances (although I don't anticipate much additional and could, or course, buy a bigger regulator in the future or change the first stage regulator to 10 lbs.



But I could also just use 10 lbs to start, although my inclination is always not to use more pressure than needed, if nothing else just to further reduce the chance of very minor nuisance leak or such.



Anyone have any thoughts on any real advantage or disadvantage on running 5 or 10 lbs. in the first stage.  It's about a 100 ft. underground run in PE to the house regulator.



thanks,



brian

Tim McElwain

Run the 10 pounds

as it is very typical of what most propane companies use. A delivery person doing a pressure check who expects to find 10 and finds 5 may feel there is a problem as most of their systems are 10 lb. You will have less problems with 10 pound and it does not change anything that will cost any money. The real key to pressures is what you do after the second stage regulator as far as piping size and distance to appliances. Go to NFPA 54 for suggested piping and plan for any additional equipment being installed now so you do not have to run new piping.



If you are planning for something like a pool heater then do some research as to size needed and the possibility of running a separate line for the pool heater.



Remember actual tank pressures depend on temperature so most of the time temps are well above the -44° boiling point of propane. If you are in areas of very low outdoor temps then for large demand  or long runs of tubing you may want to consider a vaporizer. That is however rarely needed.

lchmb

generally

we only run pressures less than 10lbs if there is a reason (higher pressure indoor's or line's passing under a slab). Tim is correct in that your better off to leave the regulator set for 10lbs, it will cause fewer issue's down the road...

archibald tuttle

got it

It looked to me like most folks were using 10 lbs. first stage, but in reviewing regulator choices I didn't think it made a lot of difference but the regulator industry at least currently offers the 5 lbs alternative so I was trying to figure it all out.



We are definitely going on the low side inside (10" WC) with piping sized accordingly. For the most part the piping is in place except for one new run.



So it seems like the industry has really standardized on the 10lbs approach. One thing that I noticed is that matched nominal 900,000 BTU secondary regulators have a hard time keeping up at 5 lbs. inlet pressure , although my use is less than 2/3 of the nominal capacities in the 900,000 btu range so it allowed me to consider the 5 lbs approach, it really seems like their matching line of secondary regulators is targeted at 10 lbs and you had to move to a commercial/industrial level of secondary regulator to get the same throughput as the 5 lbs. 1st stage was capable of putting out. 



My instinct because of this match was that 10 lbs was the standard, but I was intrigued by the offering of the two first stage pressures (or really ranges), and idly curious if anyone actually used the 5 lbseers. 



thanks,



brian

meplumber

5 lb systems more common in process heating.

brian,



I see a fair amount of 5 lb regulators on process equipment. I do not know why. It seems that the only place the I ever run across them is at a blueberry processing facility.