Hygrometer, Wet & Dry Bulb
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Product Code : SCL-PLE-11600
Quick Answer: The Hygrometer, Wet & Dry Bulb is a Mason’s pattern psychrometer that finds relative humidity from the difference between a dry thermometer and one kept wet by a muslin wick. A conversion table printed on the frame turns the two readings into humidity.
Last updated: October 2026
Key Features
- Two liquid-in-glass thermometers: dry bulb and wet bulb
- Cotton muslin wick fed from a refillable water reservoir
- Hygrometric conversion table printed on the frame
- Permanent scale markings in 1° Celsius steps
- Wall-mount hole for hanging upright
- Works without batteries or power
Technical Specifications
| Specification | Value |
|---|---|
| Instrument type | Mason’s pattern psychrometer |
| Thermometers | Dual liquid-in-glass (dry bulb and wet bulb) |
| Temperature range | Typically -10°C to +50°C (model dependent) |
| Wick | Cotton muslin with refillable water reservoir |
| Reference | Hygrometric table printed on frame |
| Frame | Moulded polymer or treated hardwood |
| Graduation | 1° Celsius increments |
| Mounting | Vertical wall mount |
About This Product
Evaporation from the wet wick cools one bulb, and the gap between the two readings shows how dry the air is, which makes evaporative cooling and latent heat visible to a class. Hung on a wall, it can be read daily for a weather diary, and students practise reading values from the printed table. Schools, colleges and institutes in Japan, Kazakhstan, Italy, Lesotho, Malaysia and Croatia can order the Hygrometer, Wet & Dry Bulb from Educational Instrument.
Frequently Asked Questions
How do you read humidity on a wet and dry bulb hygrometer?
Note both thermometer readings, find the difference, then look up the relative humidity on the conversion table printed on the frame.
Does it need power?
No. It is a non-electronic instrument that only needs water in its reservoir to keep the wick wet.
Related: Physics Lab Equipment, Hygrometer, Whirling and Thermo-Hygrometer, Digital.
For a quotation on the Hygrometer, Wet & Dry Bulb, contact Educational Instrument.
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