Propane regulator w/o excess flow protection?

[eljefino]

So I've converted my generator to a tri-fuel carb but it never really worked right. (Similar to this one). It would work if I started the generator on gasoline and switched over, but wouldn't start using its own primer button. This is the finest chineseium and comes with no instructions.

I narrowed it down, pretty surely, to the low-pressure BBQ style regulator. (Sold seperately!) The first time I hook it up, if I hit the primer button, I hear a hiss through the lines, but then can never again. I feel the "OMG I have a leak" thingie is tripping. It is supposed to always see a little positive pressure (11 inches W.C. which is like 0.4 PSI) but the carb allows it to spontaneously see ~20 inches of vacuum when the intake valve opens.

When the safety trips, it allows only a trickle of propane through. This is enough for the generator to pop and backfire, but not make RPMs or power. If I start it on gasoline it'll run just fine on propane, even with a load, until a sudden change in demand causes it to freak out and stall out. I've tried lengthening the hose (to make a buffer/ accumulator) and tried a 2nd BBQ regulator, fresh from the dump.

I would like to replace it with another low-pressure regulator without the leak protection. Do they all have it now or is there some secret handshake I can do? Secret term I can ask for? I'm pretty sure I don't want an adjustable PSI one, as it could corrupt my A/F ratio.

 

[Darwin1138]

The problem indeed is the BBQ regulator. You need a regulator that can handle the flow that your appliance is demanding. They measure this in BTU/hr. How big is your generator??

If I recall correctly you need a regulator that is at least 5 times the peak power of your generator. For example if your generator is 6.5 KW that wold be 32.5KW = 110,895 BTU/hr. So you will need a regulator of at least that value. Common numbers for regulator are in the range of a 90,000 to 1,000,000 BTU/hr A normal BBQ regulator is in the lower end of that scale.

 

[eljefino]

It's a 2.5kw/ 3.25 surge set, so I figure half that. Thanks for confirming my suspicion!

 

[eljefino]

So I got bored and went shopping. Got a Char-Broil universal hose/regulator from Walmart (PN 5184667) and a 3/8 in flare x 1/4 in MIP brass union (LFA-182) from HD.

Neither promise better flow. Same 5/16" hose. Unrated BTUs from regulator AFAIK. The adapter looks like it has a narrow spot about 1/4 inch across-- maybe this is acting as a restriction, keeping positive pressure in the hose.

I removed the hose barb from the carb and replaced it with the adapter, just to look cleaner, and so I could attach a regulator hose without destroying it.

It works... slightly better. I crack the propane tank slowly to avoid the excess flow lockup. Listen for a "good hiss" from the regulator primer button. One-in-five shot now of it starting on propane. When loads suddenly increase or decrease it doesn't shut down (much).

If I had to do it again I'd buy a factory dual-fuel unit so someone else could support it.