I recently received a $40.00 Camping World gift card. Not needing anything at the moment (15+ years of trailer camping will do that) I decided to get an ultrasonic LP level gauge.
The TRUMA LevelCheck (http://www.levelcheck.com/us/) is pretty pricey as well as CW doesn't carry it.
So I picked up the cheaper unit - a Dometic LP GasChecker:
Website -
http://www.dometic.com/USA/New...ucts/LP-Gas-Checker/
&
Video -
http://link.brightcove.com/ser...;bctid=3665167733001
$42.12. $2.12 of which was my own money.
Well, the short and sweet version - Don't bother. I give it a C grade.
I tried it on 4 very clean tanks, 2 dirty tanks, 3 completely full tanks, 2 partially full tanks, and a completely empty tank. The device had mixed readings on every tank.
I had the probe end extremely clean, held it at a 90 degree angle, put my hand on the collar, on the tank, directly behind the tank across from the device, no hand, etc... I tried tanks being drawn from, stationary tanks, ... 20 lb. tanks & a 30 lb. tank.
For $2.12 I'll hang on to it, but it doesn't even come close to the perfect-every-time hot water pour method.
I can say without hesitation don't waste your money.
Here are a few pictures (green means gas, red means no gas (yeah right)) -
