Maintaining the proper humidity levels in your environment is essential for many reasons, whether you’re a gardener, a cigar collector, or simply want better indoor air quality. A hygrometer, the device that measures humidity, is a must-have for these pursuits, but to function accurately, it needs to be calibrated. This guide will explain why calibration is necessary, how to tell if your hygrometer needs its, and provide step-by-step instructions for calibrating both digital and analog hygrometers.
Why You Need to Calibrate a Hygrometer?
An accurate hygrometer lets you know the current humidity level, so you know when to take steps to increase or reduce humidity in house. If your hygrometer isn’t calibrated, it’s like driving with a faulty speedometer - you might not have a clue about the actual humidity levels.
An uncalibrated hygrometer can lead to serious issues. Overly humid conditions an promote mold growth, while low humidity can damage wooden furniture and instruments, or even cause skin irritation. Furthermore, in a professional environment, inaccurate measurements can result in financial losses and, in extreme cases, even health risks.
Therefore, calibrating your hygrometer is key to getting reliable and precise readings and making informed decisions.
How to Tell If Your Hygrometer Needs Calibration?
Before you jumping into calibrating your hygrometer, it’s important to determine if your hygrometer is indeed needs it. Here are a few signs to look for:
- Inconsistent readings: If you notice that your hygrometer is giving wildly fluctuating readings in a stable environment, that’s a red flag.
- Comparative baseline: If you have another reliable hygrometer or a calibration kit, comparing the readings can reveal any major differences that suggest recalibration is necessary.
- Age of the device: Older hygrometers can become less accurate over time, so if yours is several years old, it might be time for calibration, even if there are no obvious signs.
How to Calibrate Digital Hygrometer?
Digital hygrometers are typically simpler to calibrate compared to analog ones. Here’s how to do it step by step:
Material Needed:
- Sealed container such as a glass jar or a resealable plastic bag
- A small bowl or cup
- Salt
- Water
- A digital hygrometer
Step 1: Prepare the calibration environment. Mix two tablespoons of salt with 1 tablespoon of water in a small bowl or cup to create a saturated salt solution, which should be thick and paste-like, not fully dissolved.
Step 2: Seal the device and wait. Place the salt solution and your digital hygrometer into a sealed container, ensuring the hygrometer does not come into contact with the solution and stays dry. Seal them up and leave them away from ventilators, air vents, or direct sunlight for 6-8 hours, preferably 12 hours.
Step 3: Calibrate the digital hygrometer. After the time is up, check if the hygrometer reads 75%. If it doesn’t, note the reading before opening the container, then take out the hygrometer and calibrate it right away. If you can’t find the calibration button, refer to its user manual.
How to Calibrate Analog Hygrometer?
Before starting, check if your analog hygrometer has a calibration feature - look at the back for a calibration screw, and you might need a flat head or a eyeglass screwdriver. If you can’t find it, you may need to upgrade to a hygrometer with calibration feature. Once you’ve confirmed it, you can calibrate your analog hygrometer the same way you would with a digital one. Alternatively, you can try the boiling water method below.
Material Needed:
- A small pot
- Water
- A analog hygrometer
Step 1: Boil water in a small pot.
Step 2: Put the hygrometer in the steam for a few minutes, make sure it doesn’t touch the boiling water directly. To protect yourself from burns, you can wear heat-resistant gloves or use clamps.
Step 3: You hygrometer should read a steady 100%. If it doesn’t, note how much the deviation is and adjust the calibration screw accordingly.
How Often Should You Calibrate a Hygrometer?
The frequency of calibration depends on usage and environmental conditions:
- Every 6 months: For home use, calibrating every six months is generally advisable.
- More frequent calibration: If your hygrometer is used in environments with extreme temperature and humidity fluctuations, consider calibrating more frequently, perhaps every three months.
- Post-movement or change in environment: Always recalibrate after moving the device to a different location, especially if the new condition is quite different.
