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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A semiconductor sensor is used to measure the relative humidity so the measurement response time is much quicker than the traditional wet and dry bulb method that can take 20 minutes or more to reach steady-state conditions, at which point the temperatures of the bulbs can be read. Please note our new address: The reference values are set using the controls for the chamber and measured independently using calibrated equipment.
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. Content only available by subscription.
In some instances, test records for climatic condition 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. Guidance on the estimation of the probability of condensation prior to paint application.
The Dewmeter gauge displays the parameters to one decimal place. 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 aspirated psychrometer is more accurate than the sling whirling psychrometer see Method Band it offers advantages in regard to the space which it requires, the possibility of using alternative types of thermometers for example, electricaleasier shielding of thermometer bulbs from extraneous radiation, accidental breakage, and convenience.
This is shown daily in the layer of moisture that collects on a cold windowpane in the presence of boiling water or, more interestingly, on the outside of a glass of cold beer. This standard is also available to be included in Standards Subscriptions. Surface temperature measurements are also made at low and high values and the external temperature measurement is checked at four values across the range. The accuracy of the electronic measurements can be shown to be as indicated on the calibration certificate and the speed of response of the electronic gauge can show the effects of the presence of humans in the area, particularly if the area is enclosed or the effects of changes in a prevailing wind if the work place is exposed.
Recent Developments in the Measurement and Monitoring of Climatic Conditions
Caution should be taken when handling mercury and mercury containing products. This is also true for whirling and sling hygrometers as when these encounter immovable objects such as pillars the tendency is to break the spirit-in-glass thermometers.
Examples of these measurement devices are shown in figures 1 and 2 below. By this method, Contractors and Inspectors can ensure that moisture is not condensing on the surface to be coated from the surrounding atmosphere.
The feature in the electronic Dewmeter that displays the calculated wet bulb temperature and the measured dry bulb temperature the air temperature, Ta has good agreement with the wet and dry bulb method in conditions of stable relative humidity. Historical Version s – view previous versions of standard. Register for a trial account.
Note — Ta will be the same value as Tdb. Please first log in with a verified email before subscribing to alerts. The values quoted in table 1 are obtained from the calibration software and can be shown to a resolution of two decimal places.
No further reproductions authorized. Using the electronic Dewmeter Gauges ensures that changes 3e37 the microclimate that can exist in enclosed areas can easily be recognized and the data-logging feature means that an accurate record for the duration of a process, either the application of the paint or the subsequent cure f337, can be made.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. Even when an Electronic Dewmeter is taken from a warm office or car to a cold environment, an accurate reading of rh can be obtained in less than 30 seconds.
The value of the Dewpoint Temperature mainly depends on the Relative Humidity of the air, that is the volume of moisture contained in the air at a given awtm compared to the maximum volume of moisture that this volume of air could contain if it were saturated at that temperature. The memory capacity is a maximum of 25, records or sets, in up to different batches.
ASTM E337 – 15
aztm There are several operational aspects of the wet and dry bulb hygrometer method for measuring humidity that influence the accuracy of the measurement including insufficient whirling so steady-state conditions are not reached, contamination of the water so optimum evaporation conditions for the wet bulb are not achieved, the use of f337 thermometer in place of the environmentally unsound mercury-in-glass thermometers.
Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. If you like to setup a quick demo, let us know at support madcad. Ast, the document is revised or amended, you will be notified by email. Link to Active This link will always route to the current Active version of the standard. In this case, the instrument w337 a wet-bulb thermometer only. Figure 5 — Dewpoint Meter Configured for Data-Logging Data can be recorded using two methods, user activated recording of values as and when required xstm the e3337 mode, with reading sets recorded automatically at the end of the pre-set interval.
Caution should be taken when handling mercury and mercury containing products. You may delete a document from your Alert Profile at any time. The traditional method of evaluating the climatic conditions for painting has significant limitations in practise due to the time taken to obtain readings and the potential errors of these readings.
Figure 3 — Digital Electronic Dewpoint Meter It can clearly be seen that if a adtm is cooled sufficiently the surrounding air will eventually give up its moisture to the cool surface.
There were no books found for the applied search filters. 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. 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 from a surface as it warms up.
Enter your personal account email address to request a password reset: No other units of measurement are included in this standard. It is critical to the service life of a protective coating system that the asttm is applied to a clean, dry surface, in order to ensure that contamination is not trapped within ashm system either between the primer coating and the substrate or between subsequent layers that make up the full protective system.
Data stored in the memory of the Dewpoint Meter can be transferred to a computer operating data management software.
To simulate the practical operation of the Dewmeter, the calibration is carried out at low and high values of RH, with low and high values of Ta. Table 1 shows the typical e337 reference values for these parameters that appear on the calibration certificate.
Our office will be closed from December 21st until January 2nd The Electronic Dewpoint Meters can be placed in the humidity chamber and the measurements monitored using the data output feature to achieve calibration against another relative humidity gauge that is separately calibrated for trace-ability.