Quote:
Originally Posted by Jim Bennett
I know a couple people with them and am fairly sure they don't pour hot water on them to read them. Almost positive. On Canada Day weekend there will be a trailer there with them, and I will quiz then on their experiences.
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Now we're getting somewhere...
If the propane is in use, and preferably at a high rate (not just the refrigerator), then the propane is chilled by the vapourization required to keep up with vapour withdrawal. Up to the liquid level the tank wall will be much colder than above it, where the propane is vapour. You can feel, or see (as condensation or even frost), or measure (with Tom's non-contact thermometer or an LCD strip) the difference in temperature... no hot water required.
If the propane is not flowing, everything is at the same temperature, and there is no way for a temperature measurement to determine level. Thus, the instruction from the
Magnetic Propane Tank Gauge web page which Tom quoted. The strip (or other temperature measurement) shows where the liquid conducts heat more effectively than the vapour.
Quote:
Originally Posted by Brian Van Snell
The original question from Bob asked about whether a simple propane gauge which can be obtained for about $15 would let you know whether you have enough propane.
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The answer is "it depends"...
Quote:
Originally Posted by Brian Van Snell
When the gauge shows the propane level is low we can get the tank filled or swap it with one we know has enough propane.
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It depends on whether or not the propane is in use. If the propane is flowing, the chilling effect lowers the pressure, and when remaining amount gets low enough the temperature (and thus pressure) drops, as indicated on the GasWatch or similar gauge.
If the propane is not in use, it is at the surrounding temperature. Since the cheap gauge measures nothing but pressure, and the pressure depends on nothing but temperature, the reading will be the same regardless of the propane level. One drop left or completely full gives the same reading.
These pressure gauges tell you if you are about to run out, while using the propane. If you check it before leaving on a trip, while no propane is being burned, it will always tell you that you have lots left, even if you have almost none.
Of course, we've been through all of this before, with the same conclusions because the science has not changed, but many members seem unwilling to look at the old discussion threads.