Bubbling method

As a general rule, there is an economic break-even point at ca 0.08 mm, which coincides with the defined difference between film and sheet. Film is made mote economically by the bubble method and sheet by the tenter-frame method. The exact thickness for break-even depends on technological improvements, which can be made in both processes, in the degree of control used in regulating them and in quaUty requirements. 

Immediately after the running test, any compressor intended for toxic, hazardous, flammable, or hydrogen-rich service should be gas tested with an inert gas to the maximum seal design pressure. The test is held at least 30 minutes and the casing and its joints checked for leaks, using a soap bubble method or other suitable means for leak detection. When no leaks are detected, the compressor will be considered acceptable. 

A method similar to the falling-ball method is the bubble method. A vial is filled with liquid, leaving sufficient room for a bubble that can equal the diameter of the vial. The vial is inverted and the time required for the bubble to pass two predetermined marks is determined. The viscosity will be directly proportional to the time required for the bubble to rise. 

Qtc is zero because Qx 0. Thus, for zero flow rate, the equation reduces to the well-known Tate s law, which is used for finding the surface tension of liquids by the pendent drop or the forming bubble method. 

The bomb method is quite similar to the bubble method except that the constant volume condition causes a variation in pressure. One must, therefore, follow the pressure simultaneously with the flame front. 

As in the soap bubble method, only fast flames can be used because the adiabatic compression of the unbumed gases must be measured in order to calculate the flame speed. Also, the gas into which the flame is moving is always changing consequently, both the burning velocity and flame speed vary throughout the explosion. These features make the treatment complicated and, to a considerable extent, uncertain. 

Test methods described in the literature inelude the bubble method, helium mass speetrometiy, liquid tracer (dye), head spaee analysis, vacuum and pressure decay, weight loss and gain, and high voltage leak deteetion [6]. 

The methods so far discussed have required more or less tabular solutions, or otherwise correction factors to the respective ideal equations. Further, if continuous measurements need to be made, then it is not easy to use some of these methods (such as the capillary rise or bubble method). 

This method for evaluating A 7 superior to the electrokinetic bubble method of McTaggart and Alty, or to employing a filter paper soaked... 

Sakugawa, H., and I. R. Kaplan, Atmospheric H202 Measurement Comparison of Cold Trap Method with Impinger Bubbling Method, Atmos. Enriron., 21, 1791-1798(1987). 

More recently [34] it was discovered that the C02 treatment is much more efficient if a semi-continuos apparatus (called a micro-bubble method) is employed instead of the batch apparatus the contact surface between the gas and the medium where the microbes live is much larger, as the liquid appears in the form of micro-bubbles created by the turbulence of the gas-flow. In this way, the diffusion to the liquid phase is enhanced as well as the material... 

Immediately following the initial assembly (and at any other time leaks are suspected), the box and purification train should be tested for leaks. A quick test for leaks is to pressurize the dry box until the gloves stick straight out. The gloves should remain in this position for several hours if no leaks are present. If leaks are indicated, testing is most easily accomplished while the box is pressurized. If the inert atmosphere is helium, the preferred method is the helium sniff test. All joints, welds, and connections should be checked. In the absences of a helium-sensitive probe or if the inert atmosphere is other than helium, the bubble method may be used a small amount of soapy water is placed on leak-prone welds and joints and the appearance of any bubbles is noted. 

Important techniques to measure the surface tension of liquids are the sessile drop method, the pendant or sessile bubble method, the Du-Notiy ring tensiometer, and the Wilhelmy-plate method. 

Some of the commonly used techniques for measuring contact angle [215, 216, 217] are the sessile drop method, captive bubble method and Wilhelmy plate method. These techniques have been extensively used and well documented for characterisation of modified PE surfaces [218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230] for various applications. Whitesides et al. [231 ] studied the wetting of flame-treated polyethylene film having ionisable organic acids and bases at the polymer-water interface. The effect of the size of substituted alkyl groups in amide and ester moieties on the surface hydrophilicity was also studied [232]. The biocompatibility of the polyethylene film surface modified with various water-soluble polymers was evaluated using the same technique [233]. The surface properties of hy-perbranched polymers have been very recently reported [234]. 

The captive drop and captive bubble methods, variations of the sessile drop method, have been developed for the determination of very low values of surface or interfacial tension [140,141], including at elevated temperature and pressure [141]. 

The captive bubble method was applied to quantify the wettability of the resist in contact with water, with surfactant solutions of different concentration and with water after contact with the surfactant solution. The wafer piece is mounted with the photoresist layer down in a cuvette filled with the solution of interest. Through a small hole in the wafer an air bubble is placed under the photoresist surface. The shape of the drop is analyzed while its volume is slowly increased and decreased and the contact angle of the bubble is computed. It has to be converted into the water contact angle by subtracting its value from 180°. 

Photoresist layers processed at the threshold dose have a thickness of about 5 nm which is too low to show a swelling effect detectable by ellipsometry. However, long-time contact angle measurements using the ADSA captive bubble method revealed a decrease of the contact angle with time as shown in Fig. 7. At the beginning, the water contact angle was 50°. After 50 h a value of only 39° was obtained. It is assumed that the decrease in con-... 

To find out whether a hydrophobizing effect can be obtained by surfactant adsorption, photoresist layers processed with exposure doses between 50% and 120% of the threshold dose have been investigated by the captive bubble method. Their receding contact angle was first... 

Scheme 2 Comparison of the geometries of the receding contact angle responsible for the capillary forces between photoresist lines in the photolithographic process (left image) and the receding contact angle measured by the captive bubble method (right image)...

Measurements on molten metals. The maximum bubble pressure method has proved one of the most satisfactory, but sessile drops, and drop-volumes have also been used with success.2 The principal difficulty lies in the proneness of metals to form skins of oxides, or other compounds, on their surfaces and these are sure to reduce the surface tension. Unless work is conducted in a very high vacuum, a freshly formed surface is almost a necessity if the sessile bubble method is used, the course of formation of a surface layer may, if great precautions are taken, be traced by the alteration in surface tension. Another difficulty lies in the high contact angles formed by liquid metals with almost all non-metallic surfaces, which are due to the very high cohesion of metals compared with their adhesion to other substances. 

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