1. Product Overview
The Sper Scientific 736740 Mason's Hygrometer is designed for accurate humidity measurement using the wet and dry bulb method. It features two thermometers, one kept wet by a siphon reservoir and the other providing a dry temperature reading. Humidity is determined by comparing these two readings with the included chart. This model utilizes a safe, easy-to-read red liquid instead of mercury and offers dual scales in Celsius (-10/50°C) and Fahrenheit (10/120°F).
Image 1: Sper Scientific 736740 Mason's Hygrometer. This image shows the full hygrometer unit, featuring two vertical thermometers, a water reservoir at the bottom, and a hanging tab at the top.
Key Features:
- Measures humidity using the Mason's Hygrometer principle.
- Features a safe red liquid for temperature indication.
- Dual temperature scales: -10/50°C and 10/120°F.
- High quality construction for reliable performance.
Image 2: Labeled components of the Sper Scientific Mason's Hygrometer. This image highlights the "Dry Bulb Thermometer", "Wet Bulb Thermometer", and "Reservoir" on the device.
2. Setup Instructions
- Unpacking: Carefully remove the hygrometer from its packaging. Inspect for any visible damage.
- Filling the Reservoir: Locate the water reservoir at the bottom of the hygrometer. Fill it with distilled water.
- Wick Placement: Ensure the wick from the wet bulb thermometer is properly submerged in the distilled water within the reservoir. The wick should remain consistently wet to provide accurate readings.
- Mounting: The hygrometer can be placed on a flat surface or hung using the integrated hanging tab. Choose a location that allows for adequate air circulation and is not exposed to direct sunlight or strong drafts, which can affect readings.
Image 3: A hand holding the Sper Scientific Mason's Hygrometer, demonstrating its portable size and how it might be positioned for reading, with a window showing outdoor conditions in the background.
3. Operating Instructions
The Mason's Hygrometer operates on the principle of evaporative cooling. The wet bulb thermometer will show a lower temperature than the dry bulb thermometer due to water evaporating from its wick, which cools the bulb. The difference between these two temperatures is used to determine relative humidity.
- Read Dry Bulb Temperature: Observe the temperature indicated by the thermometer without the wick (the "Dry" bulb).
- Read Wet Bulb Temperature: Observe the temperature indicated by the thermometer with the wet wick (the "Wet" bulb). Ensure the wick is saturated with water.
- Calculate Temperature Difference: Subtract the wet bulb temperature from the dry bulb temperature.
- Consult Humidity Chart: Use the humidity chart provided with your hygrometer (or a standard psychrometric chart) to find the relative humidity. Locate the dry bulb temperature on one axis and the temperature difference (dry bulb - wet bulb) on the other axis. The intersection will indicate the relative humidity.
Image 4: A close-up view of the Sper Scientific Mason's Hygrometer's thermometers, clearly showing the red liquid indicator and the dual Celsius and Fahrenheit scales for easy reading.
4. Maintenance
- Refill Reservoir: Regularly check and refill the water reservoir with distilled water to ensure the wick remains wet. Tap water may leave mineral deposits that can affect accuracy.
- Replace Wick: The wick should be replaced periodically, especially if it appears discolored or stiff from mineral buildup. A clean wick ensures proper evaporation.
- Cleaning: Wipe the exterior of the hygrometer with a soft, damp cloth. Do not use abrasive cleaners or immerse the unit in water.
- Storage: When not in use for extended periods, empty the water reservoir and allow the wick to dry completely before storing the hygrometer in a clean, dry place.
Image 5: The Sper Scientific Mason's Hygrometer resting on a wooden table outdoors, illustrating its durable construction and suitability for various environments.
5. Troubleshooting
- Inaccurate Readings:
- Ensure the wet bulb wick is fully saturated and clean.
- Verify the water in the reservoir is distilled water.
- Check for proper air circulation around the bulbs; avoid direct drafts or stagnant air.
- Ensure the hygrometer is not in direct sunlight or near heat sources.
- Wet Bulb Not Cooling:
- Confirm the wick is properly positioned and drawing water.
- Replace the wick if it is old or clogged.
- Ensure there is sufficient water in the reservoir.
- Broken Thermometer Tube: If a thermometer tube is broken, the unit requires replacement. Handle with care to avoid injury from broken glass.
6. Specifications
| Model Number | 736740 |
| Brand | Sper Scientific |
| Temperature Scales | -10/50°C and 10/120°F |
| Liquid Type | Red Liquid (non-mercury) |
| Product Dimensions | 2.87 x 1.26 x 11.97 inches |
| Item Weight | 3.8 ounces |
| Mounting Type | Tabletop / Hanging |
| Battery Requirement | No batteries required |
Image 6: This image illustrates various applications for the Sper Scientific Mason's Hygrometer, including meteorological stations, greenhouses, HVAC systems, and research labs, highlighting its versatility.
7. Warranty and Support
Specific warranty details are typically provided with the product packaging or can be found on the manufacturer's official website. For technical support, replacement parts, or warranty claims, please refer to the contact information provided by Sper Scientific at the time of purchase or visit their official website.
Manufacturer: Sper Scientific
Website: www.sperscientific.com (This is a placeholder link, as no specific link was provided in the JSON. Users should verify the correct support website.)
