Testing chamber, detection

A Met Glass sample was tested at 400°C with a varying mixture of He and Hj. The desired test gas was introduced into the test chamber and a mass spectrometer was used to monitor breakthrough and gas composition on the test side of the permeation apparatus. The results of the test are shown in Fig. 8. The step pressure changes for the He introduction do not result in He being detected on the sampling side, whereas, when H2 is introduced a pressure is detected by the mass spectrometers almost immediately. 

TLC the thin layer chromatogram of the tested compound may not differ from the chromatogram of the reference compound stationary phase, silica gel GF254R, mobile phase chloroform-methanol - ammonia 25% (70 40 10 vol. parts), saturated chamber, detection 254 nm. 

Emission ofDEHP from PVC wall coverings (containing 30%phthalic esters) was measured in a test chamber at room temperature, maximum concentration of 0.94 g/m3 for DEHP in air over 14-day test period (Udhe et al. 2001). Other citations within this reference noted that DEHP in test chambers was not detectable at room temperature, but maximum concentrations of 5.2 and 2 g/m3 were measured at 60 and 40 °C, respectively. Increases in DEHP emissions with increasing ambient temperature are especially... 

The most common sources of error for permeation measurements are leaks in the film between the two test chambers. Measurements at two or more different pressures in the first chamber can help detect leaks. If for example the permeation rate... 

Oxygen Uptake. A Carle gas chromatograph model GC 8700 containing an O2-N2 detection column was used to measure oxygen uptake. Samples of gas were withdrawn from the test chambers with a 10-juL syringe inserted through the silicone disc. Initial trials indicated that operator error is insignificant and that reliable reproducible results can be obtained so that 0.25 is a more than adequate error allowance. 

Table 5 Examples of compounds detected in indoor air and from building products in test chambers (see also Refs. [2,35]) ...

In 1996, investigations on PVC products were performed in test chambers under defined conditions [86]. At room temperature the DEHP concentration was below 0.1 pg m At higher temperatures the chamber values increased as expected. The maximum value was 5.2 pg m (60 °C). Wilke and Jann [87] described test chamber investigations on wallpapers containing DEHP. In tests over 28 days in chambers of 1 m (23 °C, 45% relative humidity, air exchange rate 1 h loading 1 m m ) DEHP was not detectable with a detection limit of 0.35 pg m Only when the temperature was increased to 40 °C were DEHP values of up to approximately 2 pg m measured. 

With the use of a quartz filter in front of the PUF22 the possible presence of dust in the test chambers was investigated. 50 m chamber air were sucked through the filter. The filter was weighed before and after under the same climate conditions and no dust was found gravimetrically. Even on a special gold-plated filter (nucleopore) which is normally used for determination of asbestos in air there was no detection of dust particles with an electron microscope. 

A Laser Photoacoustic Technique (LPAT) has been developed to detect and monitor outdoor photo-oxldatlon In Ethylene Methylacrylate copolymer (EMA). LPAT has been used to demonstrate that the Controlled Environmental Reactor (CER), an accelerated testing chamber that was developed at JPL, Is a valid accelerated simulator of the real-time outdoor photooxldatlon with respect to the rate of formation of the hydroxyl functional group. 

If at any time during the test, the subject detects the banana-like odor of lAA, the test is failed. The subject shall quickly exit from the test chamber and leave the test area to avoid olfactory fatigue. 

An alternative choice to the wet sipping techniques described above is the so-called dry sipping technique, for which the fuel assembly is placed into a test chamber filled with air after a short time, the fission product noble gases (in particular Kr and/or Xe) released from the defective fuel rod during heatup are measured in a gas counter. Reliability and detection limit of this technique are virtually identical to that of the wet sipping procedure. 

This SOP involves the operation of a multipurpose chemical vapor generation system for generating controlled toxic vapor concentrations over a wide range, in an approved hood or agent test chamber. This vapor generation system is primarily used for testing detection and alarm systems. 

During the SHED test, a test object filled with fuel (e.g., a tank) and/or a hydrocarbon emitting component is stored in an air-tight closed, calibrated test chamber and subjected to at least a 24 hour temperature cycle. The hydrocarbon concentration is recorded continuously for the entire test time and used to detect the permeated and/or emitted quantity of hydrocarbons [162]. 

Subjects trained to identify reproductive odors need not be conspecifics. Rats were trained to detect the estrus-specific odor in cow urine (Dehnhard Claus 1988). The olfactory discrimination apparatus consisted of a teflon cylinder attached to a test-chamber. Air flow (18 L/h) was guided through gas-washing bottles containing urine samples and then into a Teflon test chamber with the rat. Rats were rewarded for responding in the presence of estrous but not diestrous urine. Once trained these rats were used to differentiate among fractions that contained chemical constituents specific to estrus urine. 

In the ARC (Figure 12-9), the sample of approximately 5 g or 4 ml is placed in a one-inch diameter metal sphere (bomb) and situated in a heated oven under adiabatic conditions. Tliese conditions are achieved by heating the chamber surrounding the bomb to the same temperature as the bomb. The thermocouple attached to the sample bomb is used to measure the sample temperature. A heat-wait-search mode of operation is used to detect an exotherm. If the temperature of the bomb increases due to an exotherm, the temperature of the surrounding chamber increases accordingly. The rate of temperature increase (selfheat rate) and bomb pressure are also tracked. Adiabatic conditions of the sample and the bomb are both maintained for self-heat rates up to 10°C/min. If the self-heat rate exceeds a predetermined value ( 0.02°C/min), an exotherm is registered. Figure 12-10 shows the temperature versus time curve of a reaction sample in the ARC test. 

After the end of the 4-day exposure, the detectors were returned to EML for analysis. The amount of radon adsorbed on the carbon device was determined by counting the gamma rays of radon progeny in equilibrium with radon. The concentrations of radon in the buildings were determined from the radioactivity in the device and the calibration factor, obtained in a radon chamber, that takes into consideration the length of exposure and a correction for the amount of water vapor adsorbed during the exposure. The lower limit of detection with this technique is 0.2 pCi/1 for a measurement period of 4 days when the test sample is counted for 10 min, 4 days after the end of exposure. More than 90% of the radon monitoring devices were analyzed successfully. Most of the unsuccessful measurements were due to delays or losses caused by the participants. 

In addition, an interesting phenomenon was observed when pumping the sample gas through the sampling probe. The chamber air is pulled through the screens and filter, and through a dry test meter with a Metal Bellows pump. When pump is on, a steadily increasing number of detectable condensation nuclei is found. 

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