ASTM E337-02 Test Method for Measuring Humidity with a Psychrometer (the Measurement of Wet- and Dry-Bulb Temperature)

The object of this test method ASTM E 337-02 is to provide guidelines for the construction of a psychrometer and the tec hniques required for accurately measuring the humidity in the atmosphere. Only the essential features of the psychrometer are specified.... Read More

  • Average 30% Cost
    Savings

  • 100% Confidentiality
    Guarantee

  • Free, No-obligation
    Consultation

  • 100% Customer
    Satisfaction

    TRUSTED BY ENGINEERS FROM

    Scope:

    In this method humidity of atmospheric air is determined by means of wet bulb temperature and dry bulb temperature readings. This test method is applicable for meteorological measurements at the earth’s surface, for the purpose of the testing of materials, and for the determination of the relative humidity of most standard atmospheres and test atmospheres. This test method is also applicable when the temperature of the wet-bulb only is required. The test is carried out using two types method 

    Method A—Psychrometer Ventilated by Aspiration

    Method B—Psychrometer Ventilated by Whirling (Sling Psychrometer):

    Test procedure:

    The wet-bulb temperature depression, the dry-bulb temperature, and the ambient pressure provide the basis for deriving the relative humidity.

    Method A—Aspirated Psychrometer:

    Establish the airflow and maintain it until a minimum wet-bulb temperature is attained. (With mercury-in-glass thermometers, about 2-min ventilation time is usually necessary.) Read the thermometers with the necessary precision, obtaining the dry-bulb temperature with an overall uncertainty of 60.2ºC or better, and the temperature depression with an overall uncertainty of 60.2ºC or better for uncertainty in the relative humidity of 63 % RH. For an uncertainty in the relative humidity of 62 % RH, obtain the dry-bulb temperature with an overall uncertainty of 60.2°C or better and the temperature depression with an overall uncertainty of 60.1°C or better.

    Method B—Sling Psychrometer

    Holding the instrument well away from the body, and for outdoor measurements to windward and in the shade, whirl it at such a rate as to achieve the specified airspeed at the wet and dry bulbs. Read the thermometers with the necessary precision, obtaining the dry-bulb temperature with an overall uncertainty of 60.6°C or better, and the temperature depression with an overall uncertainty of 60.3°C or better for uncertainty in the relative humidity of 65 % RH.

    Test Specimen:

    Thermometers are used for measuring the Wet bulb and dry bulb temperatures.

    Data:

    Relative humidity from the psychrometric equation,

    Where,

    e = the partial pressure of water vapor in the atmosphere, Pa,

    ew (Tw) = the saturation pressure of water vapor at the wet-bulb temperature tw, Pa, 

    T = the dry-bulb temperature in °C,

    Tw = the wet-bulb temperature in °C,

    P = the total (atmospheric) pressure, Pa, 

    A = the psychrometer coefficient in K−1

    OUR SERVICES

    Core Materials Testing Services

    Metrology

    A variety of microscopy and spectroscopy tools available for precise measurements from the nano to the meter scale.

    Metrology Testing Services POPULAR TESTS:

    TEM SIMS Profilometry

    Materials Testing

    ASTM and ISO standard and custom chemical, mechanical, thermal, corrosion tests, etc. for all materials metals, ceramic or polymers.

    Materials Testing Services POPULAR TESTS:

    Nondestructive Testing Electrical Testing Chemistry Analysis

    Product Testing

    Thousands of tests for product quality and reliability under heat, humidity, temperature shock, vibration, drop, electrostatic discharge.

    Product Testing Services POPULAR TESTS:

    Vibration Testing Humidity Testing Accelerated Aging

    Looking for Material Testing?

    We have already delivered 10000+ Material Test results to top companies

      ddd Just share your testing requirements and leave the rest on us!
      • Quick Turnaround and Hasslefree process
      • Confidentiality Guarantee
      • Free, No-obligation Consultation
      • 100% Customer Satisfaction