digital hygrometers

[Neuromancer]

I have a number of digital hygrometers of different manufacture...some of them sync as you described, but that doesn't mean they are totally accurate...of the four I have, they range from +2% to -6% off...the only way to be sure is to test them under test conditions and mark them so you know for sure...

Boveda-Humidipak Hygrometer Calibration Kit

[Hugh Jorgan]

Neuro is correct, you need to make sure to do a calibration test on the hygrometers to get an accurate sense of their accuracy. The Boveda works great, or you can do the standard salt test.




The Salt Calibration Test procedures are:

Materials required: Tablespoon of Plain Table Salt (NaCl)
Two Ziplock-style baggies
Bottle Cap or other suitable small container
Swizzle Stick or other such item to stir with
Distilled Water
Your Hygrometer


Place the tablespoon of salt on the bottle cap. The wide mouth ones that are used on individual serving juice or tea bottles are ideal.

Slowly add distilled water to the salt while blending with the swizzle stick. You want to add just enough water to moisten the salt so that it begins to meld into a thick paste. Do not add enough water to dissolve the salt!

Place the bottle cap with salt gently into the first ziplock bag and then add you hygrometer. Make certain the sensor is exposed and free of being block by the bag.

Seal the bag while capturing some air inside of it. Then place into the second bag and seal again. The double bags are needed to ensure that you really have a good seal as the test will not work if there are any leaks.

Then place the bag in a place that is free of direct sunlight and is of a stable temperature.

Leave undisturbed for a minimum of 8 hours.

Check the reading on the hygrometer through the transparent baggies and it should read on or near 75% RH.

Remember most small inexpensive hygrometers are only accurate to within 3% so do not be surprised if it reads 72% or 78% RH. It is exactly 75% RH within the confines of the bag due to the salt paste reacting with the air, and what your hygrometer reads differently is the amount of error.

What to do about off-reading depends on the circumstances. If your hygrometer has an adjustment potentiometer then by all means try to tweak it to exactly 75%. You should repeat the Salt Calibration Test again after making any adjustments. If your hygrometer doesn't have the ability to be adjusted and the reading is close then don't worry about it ­ just remember that your hygrometer is X% off either high or low.

If the reading is grossly in error and you are unable to adjust it, then I suggest you replace it.

And finally, let me say that hygrometers are not really necessary. You will find over time that you will gain the experience to be able to judge the relative humidity within your humidor by simply touching and smoking your cigars. - CigarNexus

[basil]

Neuro is correct, you need to make sure to do a calibration test on the hygrometers to get an accurate sense of their accuracy. The Boveda works great, or you can do the standard salt test.




The Salt Calibration Test procedures are:

Materials required: Tablespoon of Plain Table Salt (NaCl)
Two Ziplock-style baggies
Bottle Cap or other suitable small container
Swizzle Stick or other such item to stir with
Distilled Water
Your Hygrometer


Place the tablespoon of salt on the bottle cap. The wide mouth ones that are used on individual serving juice or tea bottles are ideal.

Slowly add distilled water to the salt while blending with the swizzle stick. You want to add just enough water to moisten the salt so that it begins to meld into a thick paste. Do not add enough water to dissolve the salt!

Place the bottle cap with salt gently into the first ziplock bag and then add you hygrometer. Make certain the sensor is exposed and free of being block by the bag.

Seal the bag while capturing some air inside of it. Then place into the second bag and seal again. The double bags are needed to ensure that you really have a good seal as the test will not work if there are any leaks.

Then place the bag in a place that is free of direct sunlight and is of a stable temperature.

Leave undisturbed for a minimum of 8 hours.

Check the reading on the hygrometer through the transparent baggies and it should read on or near 75% RH.

Remember most small inexpensive hygrometers are only accurate to within 3% so do not be surprised if it reads 72% or 78% RH. It is exactly 75% RH within the confines of the bag due to the salt paste reacting with the air, and what your hygrometer reads differently is the amount of error.

What to do about off-reading depends on the circumstances. If your hygrometer has an adjustment potentiometer then by all means try to tweak it to exactly 75%. You should repeat the Salt Calibration Test again after making any adjustments. If your hygrometer doesn't have the ability to be adjusted and the reading is close then don't worry about it ­ just remember that your hygrometer is X% off either high or low.

If the reading is grossly in error and you are unable to adjust it, then I suggest you replace it.

And finally, let me say that hygrometers are not really necessary. You will find over time that you will gain the experience to be able to judge the relative humidity within your humidor by simply touching and smoking your cigars. - CigarNexus

Thanks, I appreciate this post - I'll run the test on the two hygros I have for a comparison and post results.

[basil]

12 hours following above test:

Little Havana - 75
The Perfecto - 76

[Hugh Jorgan]

12 hours following above test:

Little Havana - 75
The Perfecto - 76

Looking good!

I suggest you run the same test again for assurance.

[basil]

heh - also, the test was conducted in a drawer of a file cabinet. The metal top of the cab almost sucked the LH right out of my hand - it's got a stronger magnet in it (for mounting).

[Neuromancer]

Neuro is correct, you need to make sure to do a calibration test on the hygrometers to get an accurate sense of their accuracy. The Boveda works great, or you can do the standard salt test.

They recommend against doing the salt test with digital hygometers as the salty air inside the ziploc can corrode the electronic circuitry...I blew out one digital that way...use the Boveda test...much safer...

[basil]

Thanks for heads up - already ran one test. will skip second and hope the hyg. don't rust out. will keep the web site for future ref.

[Bull]

Any thoughts on this test? That's where you damped a kitchen towel (not soaking wet), then wrap the hygro in it for 50 minutes. Rh shoud read %100.

Sounds a lot easier...is it as effective?

Moo

[basil]

The 1st thing that comes to my mind is that measuring the extreme end of any scale (in this case, the '100' mark of a hygro that goes to 100), would not allow for standard deviation(s) to develop; this would make results of a test or group of tests unreliable. Using virtually any other mark on the scale (except '0'), would be better - this way you can express accuracy as x +/- y degrees of rh. So, a valid test that produces any specific rh environment that falls somewhere between the extreme ends (in this case, 75) within which to check an instrument can have results that can be repeatedly duplicated, or, reliability. I think.

added - but, as someone pointed out earlier, experience maybe can minimize the need to even use hygrometers; just keep the box where you like it, rh-wise. I notice all cigars don't smoke the same out of the same environment - a Torano 59 torp smokes much wetter and is harder to draw than an Oliva rob. from the same box/rh (73).

Boils down to what works for you.