Tapering glass tubes

Variable-Area Flow Meters. In variable-head flow meters, the pressure differential varies with flow rate across a constant restriction. In variable-area meters, the differential is maintained constant and the restriction area allowed to change in proportion to the flow rate. A variable-area meter is thus essentially a form of variable orifice. In its most common form, a variable-area meter consists of a tapered tube mounted vertically and containing a float that is free to move in the tube. When flow is introduced into the small diameter bottom end, the float rises to a point of dynamic equiHbrium at which the pressure differential across the float balances the weight of the float less its buoyancy. The shape and weight of the float, the relative diameters of tube and float, and the variation of the tube diameter with elevation all determine the performance characteristics of the meter for a specific set of fluid conditions. A ball float in a conical constant-taper glass tube is the most common design it is widely used in the measurement of low flow rates at essentially constant viscosity. The flow rate is normally deterrnined visually by float position relative to an etched scale on the side of the tube. Such a meter is simple and inexpensive but, with care in manufacture and caHbration, can provide rea dings accurate to within several percent of full-scale flow for either Hquid or gas. 

A 50 c.c. burette B closed by a rubber stopper, traversed by two glass tubes, one of which communicates through the clipped rubber tube p" with the side tube of the Mariotte s bottle A. At its lower end the burette is connected with a clipped rubber tube p terminating in a tapered glass tube passing through a rubber stopper. 

Procedure. To the solution of aniline in a 3-ml tapered glass tube add the Na I followed by chloramine-T. Agitate the tube for 1 min then adjust the pH to 11 with NaOH (indicator paper). Extract the labeled aniline with three 1-ml portions of chloroform and evaporate the combined chloroform extracts to dryness under a stream of dry nitrogen. The residual product is dissolved in 100 /aI of 0.1 M HCl. 

These ampoules have the form of a small ovoid balloon. They are terminated by a tapered glass tube, and their capacity is a little greater than one cc. 

The most important area meter is the rotameter, which is shown in Fig. 8.22. It consists essentially of a gradually tapered glass tube mounted vertically in a frame with the large end up. The fluid flows upward through the tapered tube and suspends freely a float (which actually does not float but is completely... 

Typical designs are rising float in a tapered glass tube (for transparent fluids) rising float in a metal tube (for toxic/dangetous fluids). Inquiry sheet shorrld merrtion the following ... 

A. 3-Amino-2,4,6-tribromohenzoic acid. The bromination apparatus consists of a 2-1. three-necked standard-taper flask A, equipped with a Trubore stirrer and attached by rubber stoppers and glass tubing to two filter flasks, B and C, as shown... 

In a crystal-pulling procedure using a tri-arc furnace (Fig. 2), a resistor box, a d.c. power supply (300 A, 80/40 V) and a set of water-cooled power cables are used to bring power and water to the electrodes. The upper part of the furnace is equipped with three equally spaced copper cathodes, to which are fixed W-Rh electrodes. The upper part (cathode) is separated from the lower part (anode) by a transparent quartz glass tube. In the bottom of the furnace there is a tapered opening for a water-cooled copper hearth containing the boride melt. All parts of the furnace are also water... 

Connect a short length (12 cm.) of glass tubing equipped with a male standard-taper joint to the flask and immerse flask in a boiling water bath until the volume of the liquid is reduced to about 5 ml. Avoid prolonged heating after the alcohol has evaporated and run the next step as soon as possible. It is undesirable to hold this alcoholic solution overnight. 

The lower part of the barrel of the dropping funnel should be bent in such a way as to offset it from the path of the thermocouple to permit adjustment of the latter. The checkers used a 8-mm. glass tube bent for offset and fitted at the upper end with a nitrogen inlet and a standard-taper ground joint to permit at-tachment of funnels of various sizes. 

Following is a brief description of the manipulation in making these bulbs Take a piece of soft glass tubing about 5mm diam and heat to redness in a hot tapered flame. Remove from, the flame and draw out a capillary about... 

A new system for grafting copolymerization was described by Kojima and collaborators (126), in 1971, involving tri-n-butyl borane and water, at 37° C, for 2 hrs, in a taper joint glass tube. This system was inefficient when organic solvents like cyclohexanone, n-hexane, tetrahydrofurane, and toluene were used instead of water. 

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