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Registered Member #39190
Joined: Sat Oct 26 2013, 09:15AM
Location: Boise National Forest
Posts: 65
Conundrum wrote ...
Probably why He is used in hard drives.
He is all about reducing aerodynamic drag...which reduces power consumption...which allows more storage in the same size case or, alternatively, a wider operating temperature.
Registered Member #61521
Joined: Mon Mar 20 2017, 11:58PM
Location:
Posts: 6
Butane is nice for many reasons and flashover inside the probe without oxygen is not a combustion hazard, however if you heat the probe the liquid butane will become a gas increasing the pressure and that could cause the probe body to rupture. So less liquid is better from a temperature-pressure prospective.
The attached patent page is all about cooling electronics. This page has a table of breakdown voltages for a few gases.
R152A (computer duster or canned air) is available in 12 oz cans for $3 in North America at 73.5psi it’s about 80% of the R114 breakdown voltage (used at the lower 32.1psi).
SF6 at 37.8psi would have the same breakdown voltage as R114 at 31.1psi. The probe manual has an upper operating room temperature of 55C which is 58psi from the table below. The manual also references a document and by exempting class 3 the upper operating temperature is 75C, I could not find the document so the exemption might be no people around, expect the probe to catastrophically fail, single use product.
I don't know the safety factor but it was designed in the 60s when engineers used slide rules and all calculations got rounded up. I would be shocked if it was less than 1.5, and 1.5 looks suspicious considering the 75C in the manual. But if you lower the upper operating temperature you get more pressure wiggle room.
Not surprising that Tektronix picked the best gas for the job, however 50 years later nothing is better.
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P6015 BNC repair
