As part of my boat project, I picked up an antique Airguide barometer. It looks great, but I've been keeping an eye on it and haven't seemed to notice any real changes in the reading. I'm not sure if that is a factor of me keeping it in the house or if it is borked.
The barometer physically is about 4" in diameter and two or three inches tall.
I don't have a vacuum gauge or anything else I can think of to modify the atmospheric pressure. Is there some hack that I'm missing?
That's pretty much all I got.
Shop vac? Bicycle pump?
I've got a shop vac. I can give it a try
Isn't this a bit like getting three clocks to show the same time?
Just look up your local weather report for the month
https://www.wunderground.com/history/daily/us/fl/tampa/KTPA
You can check for absolute accuracy or just see if it changes by the same delta from day to day.
Pete
blow on it? you should be able to move the needle with your lungs.
You need a vacuum or pressure chamber.
It doesn't take much differential pressure to register a change considering atmospheric is about 14.5 psi. 29.92 inches of mercury (Hg) at sea level
Take it on airplane. Cabin pressure is for about 5000 feet, ~ 12.23 psi.. 29.9 inches of Mercury
Or you could drive to the top of Pike's Peak, pressure is lower there. ~8.2 psi See if it moves commensurate with being at 14,000 feet.
17 inches of mercury.
I would suggest trying to adapt the science class egg trick to change pressure and see if the needle moves.
Using pressure to get egg into a bottle
I would use a large Clear Tupperware type container and place the barometer is the container on a raised platform (1-2") and make sure any reference ports in the housing aren't covered.
Add a couple inches of hot water (stay below top of platform) and then cover the the container tightly and watch the needle.
You can monitor the shape of the cover to determine if the pressure in the container is higher or lower than atmospheric and which way the needle should be moving relative to the local barometric reading.
Since you're at sea level you don't need to make any adjustments to compare with the local weather station. The weather barometric pressure is corrected to sea level when reported so actual pressure could be different from the weather report if someone is at a higher elevation.
NOHOME said:Just look up your local weather report for the month
https://www.wunderground.com/history/daily/us/fl/tampa/KTPA
You can check for absolute accuracy or just see if it changes by the same delta from day to day.
Pete
Be aware that the weather version of barometric pressure is relative, and is always normalized to 1atm. But the airport reading of BP is accurate, since it's used for a measure of altitude- so one has to correct the altimiter to make sure ground is ground.
We were always warned about that when calibrating for BP.
If just wanting to know if it is working, fill a pail with water, put it in a ziplock back and dunk the thing. Convert inches of water in the bucket to whatever units your barometer is using.
Does your barometer have a manually set pointer ? It is an easy way to see if the unit is working.
Most smartphones include a pressure sensor although you may need to download an app to interpret and display the number. I use one called 'barometer plus' and it is smart enough to use the reported figures for the nearest airport as a correction.
I have never tried to calibrate or cross check it but I do know that the pressure altitude it reports is close to what I see in the GPS mapping app I also use.
Samsung A520, about 4 years old btw.
In reply to RichardNZ :
Go on your phone and check the local weather at the monument right here it's 29.78 according to the weather channel. I think it's updated every few minutes. I'll come back and check in 10 minutes.
In reply to frenchyd :
I'm (probably) a fair way away from you but current QNH at Wellington Airport is 1003 hPa, current pressure at my place 360 ft amsl is 998.3, corrected for altitude 1002.9 so it's actually more accurate than I would have expected ...
cheers
PS have a good sleep while I settle down to my Thursday night dinner 
RichardNZ said:Most smartphones include a pressure sensor although you may need to download an app to interpret and display the number. I use one called 'barometer plus' and it is smart enough to use the reported figures for the nearest airport as a correction.
I have never tried to calibrate or cross check it but I do know that the pressure altitude it reports is close to what I see in the GPS mapping app I also use.Samsung A520, about 4 years old btw.
Very cool, I'll check it out
Can't you just borrow a known-good barometer and place them side by side for a few days?
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