Flexible tubing pressure

Flexible Tube. The simplicity of design and the absence of seals and valves make the flexible tube or peristaltic pump a good choice for low capacity and low pressure appHcations in the pharmaceutical industry or wherever shear-sensitive or moderately abrasive fluids are pumped. Because of the continuous flexing of the tube, the tube material of constmction presents a challenge regarding life cycle. For the same reason, pressures are kept relatively low. 

Flexible tubing for high pressure service, equipped with stainless steel overbraid plus tube adapter end connections, is commonly available with a carbon black-loaded PTFE core tube to dissipate static. Numerous other designs of conductive and antistatic tubing are available for low pressure applications. The utility of conductive tubing in preventing fires during transfer of aromatic hydrocarbon liquids is described in [165]. 

Figure 10-8. Single-pass shell and tube Teflon tube heat exchanger, countercurrent flow. Tube bundles are flexible tube Teflon joined in integral honeycomb tubesheets. Shell-side baffles are provided for cross-flow. Standard shell construction is carbon steel shell plain or Teflon (LT) lined. Heads are lined with Teflon . Tube diameters range from 0.125-0.375 in. O.D. the temperature range is 80-400°F pressures range from 40-150 psig. (Used by permission AMETEK, Inc., Chemical Products Div., Product Bulletin Heat Exchangers of Teflon . )...

Flexible tubing for the conveyance of fluids (fluidised solids, liquids or gases) the constmction, which includes textile and/or wire reinforcement, varies according to the pressure and the type of fluid. 

Propelling unit(s), aimed to move the samples. They are generally peristaltic pumps, although their function can also be served by piston pumps and the pressure exerted by a gas or gravitational force. They are intended to set and keep several streams in motion— the flow-rate of such streams should be regulatable and maintained as constant as possible (normally accomplished by using flexible tubes that withstand the mechanical pressure to which they are subjected). 

Peristaltic pumps [Fig. 7.12(h)] move the liquid by squeezing a tube behind it with a rotor. Primarily they are used as metering pumps at low capacities and pressures in corrosive and sanitary services when resistant flexible tubes such as those of teflon can be used, and in laboratories. 

Hydrogenation at atmospheric pressure standard procedure. This method for effecting hydrogenation at atmospheric pressure employs the apparatus shown semi-diagrammatically in Fig. 2.63(a) it is supported on a suitable metal rod framework. The essential features are a long-necked hydrogenation flask A fitted to the apparatus with sufficient flexible tube to allow shaking, a series of... 

Tubing Type Manufacturer11 Durometer Flame Resistance Flexibility Maximum Pressure (psig)c Resilience Temperature Range (°C)... 

Some burettes have a tube for easier filling attached between the calibration lines and above the tip. Flexible tubing is attached to the tube used for filling the burette. There are two methods to stop liquid flow. One technique uses a pinch clamp on the flexible tubing, and the other has a stopcock on the side tube. The pinch clamp can lead to inherent errors as the pressure from the weight of the liquid in the burette causes a small expansion of the flexible tube. As the burette is emptied, this pressure decreases, and the amount of error decreases as well. If your work requires limited accuracy, these changes are well within tolerance. Alternatively, a stopcock can be used instead of a pinch clamp. There are no hydrostatic complications with the stopcock. 

If you have pressurized air in your lab, you can use a motorless hot air gun. These units are smaller than standard hot air guns and are typically about the size of small home hair dryers. Motoiiess hot air guns only require heating filaments because they do not have fans. To use one, a flexible tube is attached to an air supply and the hot air gun. If your lab does not have plumbed-in compressed air, or the location of your outlet is too far away from where you want to use the hot air gun, another option is to use a compressed gas tank of air. Do not use compressed oxygen or any flammable gas for the air supply. You could use an inert gas, such as nitrogen for your air supply, but it would be costly. 

A mixture of the appropriate 4-substituted phenyl isothiocyanate and (dialkylamino)carbonitrile was sealed in a flexible tube. The tube was placed in a reaction vessel and pressurized at 800 MPa for 20 h. The mixture was washed with i-Pr O (20 mL). A mixture of this residue and a solution of coned HCl (1 mL) in FtOH (to mL) was heated under reflux for 0.5 h and allowed to cool to rt. The precipitate that formed was collected, washed with acetone and dried under reduced pressure. The product was recrystallized from MeCN. 

Automation of the constant pressure apparatus is not as simple. In these systems the hydrogen pressure in the reactor is kept constant by changing the volume of the system as the gas is consumed. This can be accomplished manually by raising a leveling bulb filled with a liquid and attached to the bottom of a gas burette by a flexible tube. Automation of such systems has been achieved by the use of a motor-driven device to raise the bulb with the motor being regulated by... 

Tubular filters (Fig. 10) offer low cost construction and high hydraulic capacities. They are made with both rigid and flexible tubes. Celite is used on the rigid tube filters in the usual combination of precoat and body feed. With flexible tube filters, instead of body feed, an extra heavy precoat [25-30 lb (11.4-13.6 kg) filter aid per 100 ft (9.29 m ) filter area] is used. After filter pressure has reached a maximum, the precoat is bumped from the tubes, re-slurried, then re-deposited. This sequence is repeated until pressure is no longer reduced significantly, at which time the precoat is discarded and a new one applied. 

The selection of an "inert" or "non-reactive" liquid may depend on the particular applications of the glovebox. However, desirable properties ordinarily include low vapor pressure and viscosity, a broad liquid range, and compatibility with flexible tubing materials. For organometallic applications an additional consideration is poor ligating ability, since trace levels of a coordinating coolant might compete for an active coordination site. These criteria may be met by a variety of saturated hydrocarbons (such as decane or decahydronaphthalene) which can be prepurified by distillation at reduced pressure from sodium. 

Sealed autoclaves or bombs capable of withstanding pressure greater than 1 atm can also be used. In this case, the reactants, catalyst, and solvent are added to the bomb. The reactor is heated to the desired temperature and the alkylene oxide is metered in to maintain a pressure of approximately 10-15 psig. As the alkylene oxide reacts, the pressure drops and then additional alkylene oxide can be added from a steel cylinder connected by flexible tubing to the bomb with appropriate valving. The bomb can either be heated or cooled as desired and agitation may be provided by either a rocking mechanism or a sealed mechanical stirrer. 

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