ASTM E Standard Test Method for Measuring Humidity with a Psychrometer (the Measurement of Wet- and Dry-Bulb Temperatures). Find the most up-to-date version of ASTM E at Engineering ASTM-Epdf – Download as PDF File .pdf), Text File .txt) or read online.
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Calibration of the Electronic Dewpoint Meter is carried out in a temperature controlled humidity chamber, whereas the calibration of the wet and dry bulb hygrometers is limited to assessing the accuracy of the spirit in glass thermometers. The output from this sensor is displayed as Ta. Table 1 shows the typical measured reference values for these parameters that appear on the calibration certificate.
These errors accumulate from a number of operational issues such as alignment of the lens in the glass thermometers for optimum position when reading both thermometers, parallax errors when reading the position of d337 thread relative to the scale on the glass, heat from hands transmitted to the bulbs of the thermometers and resolution of the measurement and the conversion of the readings to rh and dewpoint.
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ASTM E337 – 15
Historical Version s – view previous versions of standard. The memory capacity is a maximum of 25, records or sets, in up to different batches. Data stored in the memory of the Dewpoint Meter can be transferred to a computer operating data management software. It can clearly be seen that if a surface is cooled sufficiently the surrounding air will eventually give up its moisture to the cool surface.
For more specific safety precautionary statements, see 8. An example of this type of gauges is shown in figure 3. This sensor can be also be used for measuring the temperature of materials to be used in the process or for surface temperature monitoring during the process, data-logging.
These temperatures make allowance for the accuracy of the measurement of relative humidity and surface temperature in the field and also deal with any inertia in the evaporation aztm a surface as it warms up.
Digital humidity gauges have been available for some years but there is now a Dewpoint Meter that is designed specifically to monitor the paint process and that also provides a method for recording satm presenting data as proof of the conditions prevailing. If contamination is present it can lead to the formation of a corrosion cell and to premature failure of the coating. When an external thermocouple sensor is connected the integrated surface temperature sensor is disconnected from the gauge.
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It must be recognized that Digital Dewmeter do have an uncertainty associated with the measurement and, as electronic gauges, they must be treated with care particularly when they are used on a construction site. Our office will be closed from December 21st until January 2nd Link to Active This link will always route to the current Active version of the standard.
Similarly the data-logging axtm can be chosen when a new batch is selected by pressing the clock softkey. Note — Ta will be the same value as Tdb. We wish you and yours a Happy Holiday Season! If the document is revised or amended, you will be notified by email. However, the hygrometers described in this method use mercury in glass thermometers, which are no longer acceptable under Restriction of Hazardous Substances RoHS legislation round the world.
Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. No further reproductions authorized.
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Only the essential features of the psychrometer are specified. Measurement of relative humidity in controlled conditions is not practical for the whirling or sling hygrometer as the presence of an operator in the controlled environment causes errors.
The estimated values for the wet bulb temperature Twb and the dry bulb temperature Tdb can be displayed by selecting these parameters from the Display menu in preference to two of the usual set, e. The Dewmeter gauge displays aatm parameters to one decimal place. Caution should be taken when handling mercury and mercury containing products.
Figure 3 — Digital Electronic Dewpoint Meter. Register for a trial account. Caution should be taken when handling mercury and mercury containing products. The digital format of the gauge allows sets of reading to be stored in memory for further analysis, reporting or archiving.
The advantages of the Electronic Dewpoint Meter are in the speed and accuracy of the measurement and in the traceability of the gauge calibration to a national standard. The wireless connection will operate over a distance of up to astk m. The value of the Dewpoint Temperature r337 depends on the Relative Humidity of the air, that is the volume of moisture contained in the air at a given temperature compared to the maximum volume s337 moisture that this volume of air could contain if it were saturated at that temperature.
Recent Developments in the Measurement and Monitoring of Climatic Conditions
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Due to the operation of the whirling or sling hygrometer it is not practical to use the humidity chamber method to check the performance of these types of hygrometers psychrometers so the calibration of these rely on the calibration of the thermometers alone.
The values quoted satm table 1 are obtained from the calibration software and can be shown to a resolution of two decimal places. In some instances, test records for climatic astj monitoring require that the wet and dry bulb temperatures are entered into the record sheet so to make this process easier and quicker the Electronic Dewmeter provides estimates of the relevant wet and dry bulb temperatures based on the measurement of RH and Ta.
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