Bubble tubes

Viscosity can also be determined from the rising rate of an air bubble through a Hquid. This simple technique is widely used for routine viscosity measurements of Newtonian fluids. A bubble tube viscometer consists of a glass tube of a certain size to which Hquid is added until a small air space remains at the top. The tube is then capped. When it is inverted, the air bubble rises through the Hquid. The rise time in seconds may be taken as a measure of viscosity, or an approximate viscosity in mm /s may be calculated from it. In an older method that is commonly used, the rate of rise is matched to that of a member of a series of standards, eg, with that of the Gardner-Holdt bubble tubes. Unfortunately, this technique employs a nonlinear scale of letter designations and may be difficult to interpret. 

Bubble-Tube Systems The commonly used bubble-tube system sharply reduces restrictions on the location of the measuring element. In order to ehminate or reduce variations in pressure drop due to the gas flow rate, a constant differential regulator is commonly employed to maintain a constant gas flow rate. Since the flow of gas through the bubble tube prevents entiy of the process liquid into the measuring system, this technique is particularly usefiil with corrosive or viscous liquids, liquids subjec t to freezing, and hquids containing entrained solids. 

Carbonate ionophore I [ETH 6010] (heptyl 4-trifluoroacetylbenzoate) [129476-47-7] M 316.3, b 170°/0.02 Torr, d 0.909. Purified by flash chromatography (2g of reagent with 30g of Silica Gel 60) and eluted with EtOAc/hexane (1 19). The fractions that absorbed at 260nm were pooled, evapd and dried at room temp (10.3 Torr). The oily residue was distd in a bubbled-tube apparatus (170°/0.02 Torr). Its IR (CHCI3) had peaks at 1720, 1280, 940cm and its sol in tetrahydrofuran is 50mg/0.5mL. It is a lipophilic neutral ionophore selective for carbonate as well as being an optical humidity sensor. [Anal Chim Acta 233 41 1990.]... 

Bubbles, in fluidized beds, 11 805-806 Bubble size control, 11 805 in fluidized beds, 11 819, 821 Bubble size distribution, 12 14 in foams, 12 11 Bubble tear-offs, 20 229 Bubble tray absorbers, 1 27, 29 design, 1 83-86 Bubble-tube reactor, 25 194 Bubble tube viscometer, 21 739 Bubble two-phase theory of fluidization, 11 805-806... 

If it is difficult to provide a level tap in the base of tbe vessel (for mechanical design reasons, for example in a glass-lined vessel) a bubble tube can be sus-... 

Wet test meter, bubble tube, rotameter, and manometer Assorted spare parts pumps, fuses, orifices, etc. 

Figure 6. Schematic of apparatus measuring Os uptake. Ozone was generated by the flow of the carrier gasses over UV lamps, as in (10). The scrubs (1 and 2) are bypass tubes filled with activated charcoal used to decompose O3. Valves A, B, and C provide different paths for the gas flow. The bubble tube contained 50 ml of solution and has been previously described (24).

Figure 7. Trace of an Os uptake measurement. The uptake of Os by the instrument (see Figure 6) and by a solution in the bubble tube is measured by the UV spectral absorption difference. The ppm of (Os) concentration was calculated based on an extinction coefficient of 138 atm (22). Scrub out refers to a valve change resulting in the removal of the indicated scrub from the system. Linolenic acid (100 fxM, final concentration in 0.5 ml acetone) is added where indicated 0.5 ml (-j-). The total solution in the bubble tube is 50 mM Tris-Cl pH 8.2 (50 ml). An injection of acetone alone provided the control trace (—).

Level a tool of varying length (made of wood, plastic, or a metal beam) that contains calibrated air bubble tube or tubes, used to ensure that work is vertically plumb or horizontally level (Note Newer leveling devices make use of laser technology and electronics and may be handheld devices that do the same job.) hand level, laser level... 

Figure 13 shows the flow rate stability versus ambient air temperature. The samplers were operated in an environmental chamber over a temperature range of 0°C to 70°C. A heat exchanger was connected to the sampler inlet to ensure that the temperature of the inlet air was the same as the ambient air temperature. The sampler flow rate was monitored with a bubble tube outside the chamber. 

Figure 14 shows the altitude effect on the sampler flow rate. This test was performed in a vacuum chamber. The flow rate was monitored with a bubble tube which was mounted in the chamber and operated by remote control. Each data point is an average of 18 pieces of data three samplers and three flow rates which were monitored while both increasing and decreasing the vacuum. 

Different methods used for calibrating samplers include rotometers, wet-test meters, pressure gauges across fixed orifices, mass flow meters, hot wire flow meters and bubble tubes. Each of these calibration devices requires an appropriate correction factor. Some of the devices measure mass flow rather than volumetric flow. Sampling requires volumetric flow calibration. 

Most of the calibration devices require original calibration by a primary standard. A bubble tube is the only device mentioned that is a primary standard(8). It can be checked with simple laboratory tools. 

If the bubble tube is connected to the inlet side of the pump, no corrections are required. This requires the sampler bubble tube shown in Figure 15. If a standard laboratory type bubble tube is connected to the exhaust side of the pump, the volume of air which has gone through the sampler pump becomes additionally humidified by the soap solution in the bubble tube causing an increase in the volume. Connecting a bubble tube to the exhaust side of the pump can cause errors in the range of 1 to 3% if the proper correction is omitted(9). 

MC/ilM Analvsi s of air for the n resenee of TNT is conducted by drawing the air from one point in the room through two sintered glass bubbling tubes setup in series and contg ca 150 ml acetone, at a rate of 0.5 1/sec, for a period about 1 hr. After a partial concn of acetonlc soln by evapn at temp below 82°, the voi of concentrate is measured and 1 ml is withdrawn for test. 

Sample Preparation. The three primary resoles selected for inclusion in this study were synthesized in laboratory glassware in 4000 gram batches, using 99+% commercial phenol, ion-exchanged (low formic acid content) 50% aqueous formaldehyde, reagent grade 50% aqueous sodium hydroxide, and tap water. The three resins, coded A, B, and C, were allowed to react to the same apparent bulk viscosity as measured by the Gardner-Holdt bubble tube method. In addition to the same final viscosities, the resins also were synthesized from identical mole ratios F/P = 2.0, Na/P = 0.71. 

Total radiation Ultrasonic Strain gauges Bubble tube Ultraviolet (uv) spectroscopy... 

Fig. 40. Production diagram of oligoethylsiloxanes by the continuous technique 1-4, 9, 14, 17 - batch boxes 5, 21 - agitators 6, 36- reactors 7, 10, 11, 19, 26 - coolers 8 - forehydrolyser 12, 18, 23 - settling boxes 13 - neutraliser 15, 20, 24, 29, 40 - collectors 16 - hydrolyser 22 - heat exchanger 25 - distillation tank 27, 30, 33 - receptacles 28 - flusher 31 - purification apparatus 32 - nutsch filter 34 - pressure container 35 - circulation tube 37 - bubble tube 38 - separator 39 - trap 41 - container...

The circulation and bubble tubes are vertical apparatuses with vapour jackets. The reactors are vertical cylindrical apparatuses with spherical welded bottoms and removable lids (with cylindrical baskets" with cationite KU-23 or askanite. The reactors are fashioned with capacitance moisture indicators. To moisturise cationite or ascanite, the apparatus is filled with live steam. The separators are vertical cylindrical apparatuses with conical bottoms and removable spherical lids. The reactors and separators operate under 0.02 MPa. 

The jackets of the circulation and bubble tubes are filled with vapour the inner part of the bubble tubes is filled with air (1.5-5 m3/h) and heated to 100-115 °C. Circulation is made possible by the difference in the density of the liquid in the circulation and bubble tubes created by air in them. 

A11 solvents used should be deoxygenated by passing a stream of nitrogen through the solvent with a fritted bubbling tube for i hr. 

All solvents, methanol, chloroform, absolute ethanol, and u-hexane are dried over 4A molecular sieves and degassed by passing a stream of nitrogen through the solvent with a filtered bubbling tube for hr and then cooling to 0° before use. 

---