Closed testing

The te.st is carried out by using an apparatus shown in Figure 11.8, consisting of a closed test chamber in which talcum powder can pass through a sieve having square openings of 75 fim, and is held in suspension by an air current. The amount of talcum powder is supplied at 2 kg per cubic metre size of the test chamber. The enclosure under lest is placed inside the chamber and is connected to a vacuum pump which maintains, inside the enclosure, a differential pressure equivalent to not more than a 200 mm eolumn of water. 

These ratings can be interpreted as follows. In the case of the Time Stress PIF, all the operations have a high level of time stress, apart from close test valve, where stress is low. The operators are very experienced in carrying out all the tasks. Distractions are moderately high for close test valve, but otherwise low. Procedures are poor for secure locking nuts and secure blocking device, but above average for the other two tasks. 

No. Stages Minimum Practical Absolu te Pressures, mm. Hg. Range Operating Suction Pressure, mm. Hg. Closed Test Pressure mm. Hg. 

All apparently closed units from the 1-minute opening and closing test are then tested with children All packages that are opened in excess of 20% count against the SAUE (senior adult use effectiveness) Performance standard remains at 90% or greater... 

The pressure control system can equilibrate pressure change rates up to 20 bar/s. The outside guard heater can cope with temperature changes up to 100°C/min. A heat loss rate of less than 0.1°C/min can usually be achieved below 350°C and 25 bar [194]. The tests are run with either open or closed test cells in a closed outer bomb, which can be vented under specified conditions. The containment vessel can withstand pressures up to 100 bar. The use of a closed test cell results in the most severe pressure and temperature changes. 

Modeling studies show that Equation 2-4 should be obeyed quite closely. Tests of this equation on atmospheric data show good agreement, at least for ozone concentrations of 0.1 ppm or less. At higher ozone concentrations, deviations have been observed, although it was suggested that the method of averaging was responsible, rather than a real failure of Equation 2-4. ... 

The slope of the vapour pressure versus temperature curve, dP dT, can be obtained experimentally (see nnex 2). The most accurate method is to take tangents to the pressure (corrected for the presence of pad gas) versus temperature data from a closed test, or to fit the data to the following relationship161 ... 

The peak gas evolution rate, QGmax, can be obtained from calorimetric measurements (see Annex 2 and equations (A2.3) and (A2.4)). It is important that such calorimetric tests are performed so as to minimise the amount of dissolved gas in the test. "Open" tests are therefore preferred to "closed" tests[2]. 

In a closed test, the pressure measured is that due to the reacting system within the test cell. The pressure versus time and temperature versus time data can be used to obtain pressure versus temperature. The pressure can be corrected for the partial pressure of any pad gas to give the vapour pressure (see A2.7.1). This can be plotted on a Cox chart or Antoine plot (log pressure versus -1/ (temperature)). If the data fall on a straight line, the system is a pure vapour pressure system. If they do... 

Information on the data obtained from the open and closed tests is given in A2.4. 

SYSTEM TYPE CLOSED TEST Log P vs -1 a straight line OPEN Pressure rise in containment Vessel TEST System tempered ... 

DATA OBTAINED FROM A CLOSED TEST FOR A VAPOUR PRESSURE SYSTEM (IDEALISED)... 

It can be difficult to obtain all this information from a single test and it may be better to use a combination of a closed test (see A2.4.2) to obtain vapour pressure and rate of temperature rise data, and an open test to check that tempering continues until the reaction is complete. 

The information required for relief sizing for gassy systems is the rate of gas evolution, Qg, (for the full-scale vessel), as a function of temperature. This can be calculated from the rate of pressure rise in the small-scale test by means of one of the following equations111,121. Equation (A2.3) is the more general equation and is best used for data from closed tests ... 

A new calorimetric test was performed with this heating rate superimposed. The measured rates of temperature rise in a closed test were 150 K/minute at 2.0 bara and 220 K/minute at 2.6 bara. In each case, the rate of temperature rise due to the reaction can be calculated as ... 

CLOSE TEST TUBE WITH RUBBER STOPPER WITH GLASS TUBE DRAWN TO JET POINT. COVER APPARATUS WITH A TOWEL... 

In spite of the fact that HFB derivatives have a number of properties suitable for GC analysis, their use for steroids suffers from various problems, as can be judged from the different results obtained by different workers. Wotiz and co-workers [356,357] reported a detection limit of 0.1 ng of steroids and stated that if estrogens are determined in plasma, 2 ng per 10 ml of plasma can be analysed. Derivatization was performed by the following procedure. A 0.1-ml volume of -hexane, 1 jul of tetrahydrofuran and 2 jul of HFB anhydride were added to the estrogen fraction and the mixture was heated in a closed test-tube at 60°C for 30 min. The solvent was evaporated under a moderate stream of nitrogen at 40—50°C and the residue was dissolved in 50 jul of -hexane. GC was performed on 3% QF-1 or 2% XE-60 at 240°C. 

Acyl derivatives of triazines were used by Bailey et al. [495] for their determination in potatoes, peas and tomatoes. Their preparation requires catalysis by trimethylamine or pyridine. A 15-jul volume of HFB anhydride was added to a dry residue of triazine (1—25 ftg) in a 15-ml test-tube fitted with a screw-cap, 1.0 ml of 0.5 M trimethylamine in benzene (or 1 ml of benzene plus 6 droplets of pyridine) was then added and the closed test-tube was stirred gently for 30 sec and then allowed to stand at room temperature for 30 min. Subsequently 4.0 ml of benzene were added and the contents were stirred for 1 min, then 10 ml of water were added and the contents were shaken vigorously for 1 min. The phases were separated and a suitable portion of the benzene phase was injected. Several stationary phases (OV-1, OV-101, OV-210 and a mixture of OV-101 and QF-1) were applied at temperatures of 180—200°C or with temperature programming. Exclusively mono-derivatives are said to be prepared by this procedure, with bis-deriva-tives in small amounts and for only some substrates. The sensitivity of the analysis using an ECD is from 300- to several thousand-fold higher that with free substances. 

The closed testing principle of Marcus et al. (1976) proceeds as follows. Closed testing... 

As an illustration, suppose that g = 3. Then closed testing tests the following null hypotheses. 

It turns out that a concept more easily explained and more powerful than closed testing is the partitioning principle of Stefansson et al. (1988) and Finner and Strassburger (2002), which proceeds as follows. 

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