After at least 5 years of service I had to replace an LPG regulator. I didn't think anything of it until I was questioned by my friend(a fuel oil and LPG dealer). By the way he is not the supplier of LPG to this perticular generator. I installed the 14kw generator and gas piping originally. Here is how it is done: Approx 30' from the generator there is a 100 gallon bottle just for the generator, no other appliances. I piped it to the generator in 1/2" threaded pipe above ground. Installed a sediment tee, shutoff valve and I used the provided flex hose. At the LPG bottle, the provider installed a 2 stage regulator. Until now the machine has run great. In your opinion, should I have used a high pressure and then a low pressure regulator in lieu of a 2 stage? My friend the LPG dealer used his pipe calculation info and said that 1/2" threaded pipe is not enough volume for the machine to run at full load if low pressure LPG is flowing through it. Give me your thoughts please. Keep in mind the generator has performed great during many power outages.
First I would ask is how is the unit running now with the new regulator? If it runs fine the way it is then so be it.
From a personal stand point I do not/will not install less than 3/4" as most of the mfg. instructions recommend no less. I install the primary reg. on the tank and the secondary at the unit. Most units will run at 10-14 inches of water column. At this WC the pressure is less than 1/2 lb psi. This is probably why your friend is concerned. From the primary the pressure would be in the 100lb psi range to the secondary. If there were a heavy load coming on, the low pressure from that distance may not be enough flow for the gen. to maintain correct speed. With the secondary installed at the unit it is a very shot distance to the flow regulator on the gen.
It all comes down to supply and demand. If your gen. has been operating fine with the set up you describe then the supply is adequate to maintain the load on the gen.