Manometer for checking LPG pressure

Has anyone ever purchased or made a manometer, especially a U-tube type which seems to be the cheapest and simplist type, to have as a tool for periodically checking the LPG pressure in their RV? 

Either way can you tell the best priced place to buy one, or the easiest explanation for making one?  I've owned my coach for 8 years and it's never been checked so I figured it would be easier to do it myself than trying to make an appointment someplace and having to drive there for probably a 5-10 minute job.

Thanks

I've made a manometer for checking LPG pressure in inches of water. After I had my sticks & bricks plumbed for propane I was concerned with how much gas I was going through, and not totally confident with the installer's abilities.  I made my own u-type gauge and found that he had left the adjustable pressure reducers at the default setting of 7" of water (good for natural gas) instead of adjusting to 11" of water for propane.  I adjusted the pressure reducers and no longer had to wait 1/2 hour for the BBQ to heat up.  Here's how I built the gauge:

See attached photos.  First I built a vertical plywood "stand" shaped like an upside down "T".  The vertical piece of plywood was about 12" x 18".  Then I fastened a length of clear 1/2" vinyl hose (in a "U" shape) to the vertical plywood with copper pipe plumbing straps.  Leave one end of the hose open, ending at about the top of the plywood.  Leave the other end long enough to reach your LPG pressure test point and put proper fittings on the end. Put some water into the hose, and mark the level as zero.  Measure off increments of 1/2", labeling as 1, 2, 3, etc.  Remember that for the gas pressure to raise the water level 1/2" on one side it is also pushing down 1/2" on the other, for a total of 1" of water.


Simply connect the fitting end of the hose to whatever you want to test and turn on the gas.  The water will rise to indicate the pressure in inches of water.

TIPS:

- You can put food coloring in the water if it is hard to see.
- At 11" of water, the water level will rise 5.5" so mark your zero point at least that much higher than the start of the bend forming the bottom of the "U" to avoid pushing the water around the bend and all to one side.  You'll notice I didn't do this on my tester, will modify next time I use it.

I later tested my adjustment with a borrowed commercially available manometer and it was absolutely perfect.

Good luck!

Dave gave you a good set of building instructions.
This SITE has some info on how to use the manometer in an RV setting.

Thanks, sounds like a very doable easy project, and definitely worth while.

I'm a journeyman gasfitter and when I was still in the trade we made our manometer with a brass fitting soldering in the center and drilling out as small hole as possible for safety, connect plastic tubing, mark inches from end of tubing, then use a clear bottle of any kind filled with water. Connect the brass fitting to gas valve and run hose in to water until it quits bubbling. Read the depth on end of hose and you have inches WC. Only have to carry the hose and fitting and not a big bulky u-tube.

I just use a piece of clear tubing half full of water and a ruler.  It sort of takes three hands to keep everything lined up but it works for me.  I don't measure pressures often enough to make or purchase anything more elaborate.