Bypass conveying

However, this mode of flow usually is limited to conveying distances of L < 500 m. The Group D materials that possess wide size distributions (especially a considerable amount of fines) and/or unusual particle shape (e.g., crushed coal, petroleum coke, crushed bath, rice hulls) usually are not suited to low-velocity conveying. In these cases, the options are dilute-phase or single-slug dense-phase (i.e., these materials usually are too coarse for bypass conveying). However, when long distances are involved, dilute-phase may be the only practical option. 

For the general purpose of minimizing air flow, transport velocity, wear and power, the fluidized dense-phase mode of flow is preferred for long-distance applications. Efficient blow tank feeders, rotary-screw compressors, refrigerated dryers and stepped-diameter pipelines also are recommended. For products that are not suited to fluidized dense-phase, the possible modes of flow include dilute-phase (suspension flow) or bypass conveying (Wypych, 1995a). 

If the pump is protected using a diaphragm-type pressure switch, then the pump will be switched on automatically. If a combination of roots pump and roughing pump is to convey highly volatile substances such as liquids with a low boiling point, then it is advisable to use a roots pump which is equipped with an integral bypass line and a valve which will respond to a pre-set pressure. Example Roots vacuum pumps RUVAC WAU / WSU. 

The STh receives also direct excitatory input from the cerebral cortex, especially from the frontal cortical areas the primary motor cortex, with a minor contribution of prefrontal and premotor areas (see for review Nambu et al., 2002). Cortical afferents from the primary motor cortex in rodents and cats are composed of collaterals of the pyramidal tract or of corticostriatal fibers (reviewed by Hamani et al., 2004). The hyperdirect pathway is a cortico-STN-pallidal pathway, which conveys excitatory input from the motor-related cortical areas to the GP bypassing the striatum, and therefore with shorter conduction time. According to the model of the hyperdirect pathway, the activity of the cortico-STh-pallidal route could result in a wide inhibitory effect on motor programs, with adjustments of signals through the direct cortico-striato-pallidal pathway (Nambu et al., 2002). 

The parts of the packaging line between stations (open conveyer) should be covered so that the goods once passed through the automatic checks cannot, as far as is practical, be handled by operators again. This is because it has been reported that up to 70% of product mix-ups and adulteration in the whole British industry are caused with the supply company deliberately bypassing systems. 

BYPASS - A pipe or duct, usually controlled by valve or damper, for conveying a fluid around an element of a system. 

Given pump and motor losses and the use of a standard pump size / gear box larger than necessary, a drive motor / VSD combination of some 5 kW should be adequate for the purpose required. It is intended that the motor should be run in constant torque mode and, as such, stall when the required torque / pressure has been built up. The amount of offset required and when it should be applied / removed would be controlled by using winder conveyance position and sheave load measurements, that most modern Blair winder control systems have available to them. The pump would only be operational if the associated bypass valve were energised to block. This would enable suitable control of rope whip conditions under all operating modes. 

The saturated steam from the reactor vessel is conveyed to the admission valves of the high pressure cylinder via the four steam lines. After expansion through the HP unit, the steam passes through a steam moisture separator unit and a steam reheater, on its way to the admission valves of the three (or four) low pressure turbine cylinders. A special "steam bypass" line, from the steam lines to an intermediate extraction point, provides a means for temporary increases of the steam flow to the turbine cylinders - for power control purposes. 

Chemical hoses must be designed for a specific service. Hoses are required to convey compressed gases, slurries, petroleum products, solvents, bulk chemicals, such as acids and caustics, and a full array of other chemicals that may exhibit flammable, toxic, corrosive, cryogenic, or other harsh properties. Chemical hoses are used for loading and unloading trucks, tank cars, barges, and ships. They may also operate to bypass equipment that has been taken out of service. 

Figure 8.8 Dense phase conveying system using a bypass line to break up plugs of solids...

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