ASTM E337-15(2023) PDF

Overview

ASTM E337-15(2023), Standard Test Method for Measuring Humidity with a Psychrometer, provides a definitive approach to determining atmospheric humidity using wet- and dry-bulb temperature readings. Published by ASTM International, this standard sets out essential guidelines for assembling and using psychrometers, ensuring reliable humidity measurements in a range of meteorological and laboratory settings. The standard specifies only the fundamental elements of psychrometers, focusing on accuracy, practical assembly, and procedural clarity.

Key Topics

• Measurement Methods: Covers two main psychrometer types:
  • Aspirated Psychrometer (Method A): Utilizes forced ventilation for higher precision and is applicable for a broader temperature range (5 °C to 80 °C). This method allows for easier shielding from external radiation and can accommodate various thermometer types, including electrical sensors.
  • Sling Psychrometer (Method B): Employs manual whirling to achieve required airflow over thermometer bulbs, suitable for use from 5 °C to 50 °C.
• Humidity Determination: The core technique involves comparing wet- and dry-bulb temperature readings to derive relative humidity using established charts or calculation methods.
• Applicability: The methods are suitable for meteorological field use, standard laboratory atmospheres, and materials testing, and even for cases when only wet-bulb temperature is needed.
• Uncertainty and Calibration: Provides guidance on acceptable measurement uncertainties and best practices for periodic calibration, emphasizing measurement confidence and reliability.
• Safety and Environmental Considerations: Addresses mercury thermometer handling and relevant precautions, alongside guidance to meet local safety and regulatory requirements.

Applications

• Meteorological Measurements: Widely used for weather observation and climate monitoring at the earth’s surface, ensuring accurate assessment of local humidity.
• Materials Testing & Environmental Chambers: Critical for maintaining and verifying standard atmospheric conditions in material testing labs, product development, and quality assurance.
• Industrial & Research Laboratories: Applied in diverse industries that require precise control of environmental parameters for processes sensitive to moisture and temperature.
• Field Surveys & Mobile Operations: The portable nature of sling and aspirated psychrometers makes this test method suitable for outdoor and remote applications.

Related Standards

Several ASTM and international standards complement ASTM E337-15(2023), ensuring harmonization across humidity and temperature measurements:

• ASTM D861 - Practice for Use of the Tex System to Designate Linear Density of Fibers, Yarn Intermediates, and Yarns.
• ASTM D1193 - Specification for Reagent Water, ensuring high-purity water for wet-bulb operation.
• ASTM D1356 - Terminology Relating to Sampling and Analysis of Atmospheres.
• ASTM D3631 - Test Methods for Measuring Surface Atmospheric Pressure.
• ASTM D4230 - Test Method for Measuring Humidity with Cooled-Surface Condensation (Dew-Point) Hygrometer.
• ASTM E1 and E2251 - Specifications for liquid-in-glass thermometers and thermometers with low-hazard precision liquids.
• IEEE/ASTM SI-10 - Practice for Use of the International System of Units (SI).

Practical Value

Adopting ASTM E337-15(2023) ensures:

• Consistent, accurate humidity data vital for process control, quality assurance, and meteorological research.
• Reliability across applications by specifying methods for calibration, maintenance, and use, thus reducing human error and ensuring legal and regulatory compliance.
• International compatibility with well-established measurement principles and referenced standards, supporting global practices in atmospheric humidity monitoring.

By following ASTM E337-15(2023), organizations can confidently measure and report humidity with traceable, repeatable procedures essential for scientific integrity, industry standards, and safety compliance.