Your logic is not correct. Powder and people are not the same. Volume is volume, and particles of fire retardant are not changing size or quantity. If pressure drops substantially in an extinguisher, it’s leaking.
A can of fresh spray paint works because the seals are all still good and the nozzle isn’t clogged, and cans of used spray paint can leak out pressure or have the nozzle or other plumbing jammed up with dried spray paint.
You’re right, the pressure gauge shouldn’t change without a leak or temperature change (Boyle’s Law and such). But it’s hard to have a 100%, no-leak extinguisher. There’s plenty of points of failure to keep the thing pressurized, and the leak could be imperceptible (over months) or a rapid failure
And you wanna keep contents from settling as well, so you don’t just spray gas when trying to use it. So you mix it a bit and inspect the gauge every so often, because you don’t want it to fail when you need it most
Ideally, it shouldn’t lose pressure. But also ideally, you don’t have a fire that requires an extinguisher in the first place
But yes, you’re right on that one. “Settling” of the fire-retardent wouldn’t cause a pressure change. It’s just part of the safety inspection to check the gauge as well as to “mix” it… keeping it ready to go
Your logic is not correct. Powder and people are not the same. Volume is volume, and particles of fire retardant are not changing size or quantity. If pressure drops substantially in an extinguisher, it’s leaking.
A can of fresh spray paint works because the seals are all still good and the nozzle isn’t clogged, and cans of used spray paint can leak out pressure or have the nozzle or other plumbing jammed up with dried spray paint.
You’re right, the pressure gauge shouldn’t change without a leak or temperature change (Boyle’s Law and such). But it’s hard to have a 100%, no-leak extinguisher. There’s plenty of points of failure to keep the thing pressurized, and the leak could be imperceptible (over months) or a rapid failure
And you wanna keep contents from settling as well, so you don’t just spray gas when trying to use it. So you mix it a bit and inspect the gauge every so often, because you don’t want it to fail when you need it most
Ideally, it shouldn’t lose pressure. But also ideally, you don’t have a fire that requires an extinguisher in the first place
But yes, you’re right on that one. “Settling” of the fire-retardent wouldn’t cause a pressure change. It’s just part of the safety inspection to check the gauge as well as to “mix” it… keeping it ready to go