Hydrometer recalibration

ronte94

Hey so I wanted to make sure my hydrometer was reading accurately so I decided to recalibrate it. I was wondering if I could perform the salt test method but substitute the salt solution with propylene glycol solution and humidifier. My propylene glycol solution is supposed to maintain a 70% humidity.

Lee.mcglynn

I would use the salt test....if your confident enough with the pg solution maintaining 70rh then there would be no need to calibrate

webmost

Should it need re-calibration after initial calibration? Mine was WAY off, along the order of 35%, when I got it. Set it straight with salt. Do they go wonky over time once set into use?

beatnic

Just a friendly FYI

A hygrometer measures relative humidity in the air while a hydrometer measures the density of a liquid.

jgibv

Don't know about PG solution for calibrating, I've always used the salt test or Boveda packs for calibration since those have been proven successful...
But the PG solution might work, I've just never heard about anybody using it before.

webmost:

Should it need re-calibration after initial calibration? Mine was WAY off, along the order of 35%, when I got it. Set it straight with salt. Do they go wonky over time once set into use?

I recalibrate mine every 6 months; sometimes they're spot on, other times they're a few % points off; but they're never super "wonky" or more than 5% off from where they should be.

Gray4lines

My hygrometers just have a "calibrate" button that sets them at 75%, so the only way to go is a salt test. I can usually tell when they are reading off, and redo the salt test. Probably about every 6 mo or so for me too.

webmost

beatnic:

Just a friendly FYI

A hygrometer measures relative humidity in the air while a hydrometer measures the density of a liquid.

Oh. I thought we were brewing beer here. Never mind then.

Lee.mcglynn

Just my 2cents but if you use boveda or heartfelt your pretty much in the clear and don't even really need the hygro.... I use mine just to check the temp

Rhamlin

Just run the salt test. If its a digital and the batteries are still good chances are it'll be spot on if you calibrated correctly. I've retested mine a time or two and it always has come out at 75%

kuzi16

how to calibrate a hydrometer: CLICK

as far as a hygrometer goes, when doing the salt test aim for 4 parts salt one part water. this should give you a good salt paste to use. this past should be in a container that wont tip over. place it into a zip-loc or tupperware that is as small as you can get it while still holding your hygrometer and salt filled container. place the entire set up in a stable environment out of the sun for more than 24 hours.

after 24 hours, check on it. however far off it is from 75% Rh is how far off the hygrometer is.