Re: [VAL] re: LP valve question

[Charlie/Betty Burke <cbburke@xxxxxxxxxxxxx>]

Chris K.,

Automatic changeover regulators have been around for 30+ years.

Airstream starting using a regulator made by Fisher which would have 
been original on a 1979 coach. The Fisher is/was easily twice the size 
of the current Marshalls. Until 3-4 years ago Airstream continued to use 
the Fisher despite it's near double cost of a Marshall.

The Fisher came in two configurations. The first was with both sections 
mounted vertically. The second had the top, or changeover section turned 
90 degrees. The second one came along with the tank cover to make it 
easier to check and operate.

The Fisher used a knob with an arrow cast in it for the tank selector. 
Which ever tank the arrow pointed at was the main feed tank. When that 
tank emptied out the colored collar under the plastic cap would change 
to red. Turning the knob to the other tank would change the color back 
to green or silver and allow the now empty tank to be closed at the 
valve and removed to be refilled. Once filled one had only to remounted 
it, connect the fitting and turn the tank valve back on. It is required 
that both tank valves be fully open for a changeover regulator to work 
properly.

Marshall regulators have used several different tank selectors over the 
years. Most recently they have used a slider and a flip lever. Whomever 
makes it the theory of a changeover regulator is the same.

With a changeover valve in use it is nearly impossible to run out and 
makes gauges an unnecessary redundancy. Gauges are unreliable, 
inaccurate and if you have to work on them a royal pain. During the 
summer one 7.5 gal tank can last the whole season. Living in it in cold 
weather requires more frequent checking but once you get a feel for how 
long a tank lasts its easy.

These days leak testing with dish detergent is no longer recommended. 
Many of the detergents on the market have ammonia in them. Ammonia is 
considered hard on the brass fittings. It will accelerate corrosion on 
brass.

Charlie