Ran D-
Been reading up on your build, and others on the site, in preparation for starting my own toterhome project. Far different animal from your stealth build, but the nuts and bolts are the same. You've done a really nice job so far, with some well thought out details.
I'm writing to give you some safety concerns coming from the perspective of someone who was raised in the family buisiness of a propane company with about 15 years active experience working in the business, and the first 30 years or so of my life being around the stuff on a day to day basis. Also did propane safety training for both industry and fire departments. And believe me, this is just out of concern for your safety, and not from a know-it-all attitude.
Having your propane tanks in the same space as a source of ignition (your generator) is definitely NOT SAFE by any stretch of the imagination. You are correct in several technical aspects such as propane being heavier than air, but any potential escaping gas has to pass by the generator to get out of the opening in the floor. The range of ignition for propane is very narrow, but none the less a huge problem. A very small leak will burn right at the point of escape, and a larger leak will burn farther away from the leak as it mixes with the air until it reaches the combustion limit, but trust me if there is a source of ignition nearby it WILL find it and ignite. That enclosed compartment even with the floor opening will definitely trap escaping gas long enough for it to reach the limit of flammability. You need a vapor proof barrier completely isolating the airspace of your propane tanks from the airspace of your generator, not to mention isolated from the interior (which it may already be, I could not tell from the pics) and that would include sealing any holes gas lines or wires may pass through into the interior. Also that compartment would need floor level venting like you have under your generator.
The other thing you may not have considered is the heat generated by your generator. As you may know the pressure inside a propane tank is directly related to the temperature. The higher the temperature, the higher the pressure in a propane tank. A propane tank should never be exposed to an outside heat source. There is even potential to heat the tank enough to cause the pressure relief valve to open, causing a release of gas that could be catastrophic in an enclosed compartment with an engine running. Towards that end make sure you insulate if you put in a separating wall.
There are several possible places for propane to leak from. The tank itself can develop leaks around the valve, or the valve mechanism itself. The person filling it is supposed to check, but can you be sure particularly at one of those exchange racks where you get a different tank every time? The hoses can deteriorate and leak, any of the hose or pipe connections can develop leaks particularly with vibration in a truck situation. The regulator diaphragms can fail, or you can simply just not get a connector tight when you change tanks. Believe me I have seen and had to repair all of these situations on RV's and elsewhere. All of those components are mechanical and like anything else can fail without warning. You simply have to get the propane and generator into separate compartments. It can literally kill you.
That said, on to something a little less dramatic. I use a Honda 1000 generator for my vending trailer, similar to yours but a little smaller. It generates quite a bit of exhaust heat, and I only use it outside on the ground. I know that kind of kills the stealth aspect in your case. I use an auxiliary tank like you describe with the cap connection and the vacuum draw from a separate tank. It was a little pricey to buy, the cap, hose and tank were about $120 as a kit. It could be done a lot cheaper, all the system really is is a special cap (which your already have) and a boat tank like you would use for an outboard motor. Now I know. Come up with a cheap used boat can and you are in business. It really does work quite well. You have to top off the internal tank, then hookup the hose and go. From there it takes care of itself. We typically run our generator 40 hours or more on a weekend and I have never run out of fuel.
Keep up the good work, and keep the posts coming. I'll be putting up posts of my build as progress takes place.
See 'ya down the road.
Dave
|