Calibrate hydrometer?

[Pickle-cham]

Ive seen 2 methods to calibrate could i use them to two step calibrate a cheap digital hydrometer/thermometers too see how out they are.
1st method seal salt in bag in jar add amount of water and wait 6 hours 75%
2nd way in distilled water or ro water should have 100%
Is there others for maybe 3 step calibration?

 

[Klyde O'Scope]

Not to be pedantic, but I think you meant hygrometer (common misnomer).
Hygrometer or hydrometer?

TBH, I never thought of trying to recalibrate one. I've seen kits for calibrating (seem to use the salt method) but the kits cost as much or more than a new hygrometer. Digital hygrometers are so inexpensive, I figured they were throw-aways, and I'd just replace one if need be.

https://www.amazon.com/s?k=digital+hygrometer+with+probe&ref=nb_sb_noss_1

Might salt adversely affect (e.g. corrode) the electronics? (IDK)

But I'm interested to learn others' opinions...

 

[Pickle-cham]

Lol yeah you may be right. But wanted to check the accuracy especially as the was cheap 3 for ten bucks ones. I would check even if i got a high end digital or a super expensive analogue hair hygrometer. After all what good is a instrument if it it giving false readings. I can do a thermometer no problems.

 

[Klyde O'Scope]

After all what good is a instrument if it it giving false readings.

Well, keeping reptiles isn't exactly rocket surgery; close (±5%) is good enough from everything I've read. (YMMV) Many sources don't even agree on what ranges different reptiles should be kept at.

Calibrating my digital calipers is another story! Also, when I worked in a testing lab, the equipment was more accurate (and more expensive!)

For checking either (digital thermometers or hygrometers) I usually just round up as many as I can find and stick them in the same environment until they stabilize. Either they're all within a reasonable range, or they're all out of kilter! So far, all the thermometers have been ±1°F (even though they're rated ±2°F) and all the hygrometers (which are combo thermometers) have been ±1% (rated ±1%).

IMO, that's close enough for 'zards. ?

 

[Pickle-cham]

Thermometers are +/- 1 and hygrometers are all close within 1 % @ 21 degrees so ok batch. They get in accurate above 80%and below 20% i believe

 

[Klyde O'Scope]

Thermometers are +/- 1 and hygrometers are all close within 1 % @ 21 degrees so ok batch. They get in accurate above 80%and below 20% i believe

I've not heard or read that. Do you perchance have a source? Could it have been with regard to analog hygrometers? A quick search sent me to Wikipedia, which describes the 2 major digital types as follows:

https://en.wikipedia.org/wiki/Hygrometer
Modern hygrometers
Capacitive
For applications where cost, space, or fragility are relevant, other types of electronic sensors are used, at the price of a lower accuracy. In capacitive hygrometers, the effect of humidity on the dielectric constant of a polymer or metal oxide material is measured. With calibration, these sensors have an accuracy of ±2% RH in the range 5–95% RH. Without calibration, the accuracy is 2 to 3 times worse. Capacitive sensors are robust against effects such as condensation and temporary high temperatures.[6] Capacitive sensors are subject to contamination, drift and aging effects, but they are suitable for many applications.

Resistive
In resistive hygrometers, the change in electrical resistance of a material due to humidity is measured.[6] Typical materials are salts and conductive polymers. Resistive sensors are less sensitive than capacitive sensors – the change in material properties is less, so they require more complex circuitry. The material properties also tend to depend both on humidity and temperature, which means in practice that the sensor must be combined with a temperature sensor. The accuracy and robustness against condensation vary depending on the chosen resistive material. Robust, condensation-resistant sensors exist with an accuracy of up to ±3% RH (relative humidity).

 

[Pickle-cham]

I've not heard or read that. Do you perchance have a source? Could it have been with regard to analog hygrometers? A quick search sent me to Wikipedia, which describes the 2 major digital types as follows:

Will see if can find it

 

[Pickle-cham]

Will see if can find it

Here but also heard it on cigar forums ?

 

[Klyde O'Scope]

The way I'm reading that, there's only 0.5% difference outside that 20%-80% range.

 

[Pickle-cham]

I thought the instrument usually has a range tapered either end of extremes wth accuracy decreasing . Any ways using cheap digi thermo-hydrometer, till i get a decent hair analogue to keep these in check. Imo a capacitive_ digi sensors wouldnt suite a long term probe exposure before loosing calibration. Just spot checks. Wifi data transfer ones i seen look bulky.
Will be testing some rasp pi sensors and transmit data from outside cage is where i want my set up headed. But needed something to at least give me benchmark parameters?