Two valve arrangement

The usual method of promotion was to wipe the oleic acid onto the cleaned outside of the tube before the experiment commenced, although it was also found possible to add the promoter to the jacket steam line via a two-valve arrangement. Tests showed that the original wiped-on film remained effective for at least 8 hours, but some improvement in over-all heat transfer coefficient resulted from the use of additional promoter after 30 to 40 hours operation. 

A typieal TPG valve arrangement is the five valve system (Figure 6-41). The two expander inlet valves provide regenerator pressure eontrol, overspeed proteetion, and flue gas shut-off to the expander. The expander exhaust valve enables expander isolation. The full and partial expander bypass valves permit aeeurate eontrol of the FCC proeess when the expander is not in operation. 

Before this particular start-up, a double block valve arrangement was installed in the bottom discharge line. It was not realized, however, that the second valve created a dead space between the two block valves and that water was trapped between them. 

The correlations for sieve and bubblecap trays have no provision for multipass flow of liquid. Their basic data may have been obtained on smaller towers with liquid flow equivalent to two-pass arrangement in towers 8 ft dia. The sieve tray correlation should be adapted to multipass flow by comparison with results obtained by the valve tray correlation in specific cases. 

The primary system is intended to isolate the major equipment in order to prevent reverse flow and exhaust oxides in a gaseous state. It consists of a special restraint type valve (check) and two motorised shutdown valves, arranged in series. The system includes a low pressure detector on the main pipe that trips the sulphuric acid pumps, isolates the process and stops the helium flow into the reactor and heaters (emergency system EAS-200). 

Design for lift-assistance is associated with pressure recovery downstream of the valve seal. Generally, two approaches are adopted 1) a valve arrangement with huddling chamber as shown in Fig. 2(A) and 2) a valve arrangement with a deflector plate as shown in Fig. 2(B). Both approaches require extra disk area outside the sealing area on which the recovered pressure may... 

A typical AC system (Fig. 2.3) consists of two beds packed with AC and a valve arrangement to direct the flows. The stream of SLA is directed through the first bed until it is exhausted, or for a predetermined time, at which point it is switched to the second bed. The spent bed is then regenerated, usually with low-pressure steam, and the steam-solvent mixture is condensed. The regenerated bed is then cooled by blowing with atmospheric air before being put back on-stream. 

Figure 9.14 shows two valves which are arranged in series in the sense of reliability ( OR gate logical union). The valves are normally open. The undesired event in this case is the interruption of flow. This can occur if any one of the valves, V-1 or V-2, or both fail adopting the closed position ( fail closed ). 

Example 9.17 Application of the fault tree method to a pressure relief system A vessel is equipped with four valves, which are arranged in two trains with two valves each, as shown in Fig. 9.18. The trains serve to relieve the tank in case of overpressure. 

Two valves to regulate the hot gas flow through the test section were provided. They have a nominal width of KXK) mm and are arranged in the hot gas duct behind the bypass branch and before the bypass reentrance. There are also two smaller valves in the bypass line with a nominal width of 830 mm and also in the hot gas extraction line with a nominal width of... 

Coinjection n. A process similar in its results to coextrusion but accomplished by modifications of the injection-molding process. By means of various nozzle and valving arrangement, two or more materials, can be injected either simultaneously or sequentially to form an article with an outer shell of one material with certain desired properties, the shell filled with another material to attain other desired properties such as reduced cost. Coinjection, like coextrusion, basically means that two or more different plastics are formed into a composite or laminated structure. 

The feedwater lines enter the containment via two lines, each with inner and outer isolation valves, splitting up into four lines adjacent to the RPV for connection to four nozzles, at "mid-height" of the vessel. The nozzles and the internal removable feedwater distributers are of a special ABB Atom design that ensures a "thermal sleeve" protection against the "cold" feedwater for the RPV wall, and efficient distribution into the downcomer. The feedwater flow rate is adjusted to match the steam flow rate from the vessel, to keep the water level within close limits, by speed control of the feedwater pumps at high power operation, but valve arrangements enable flow rate control also at low reactor power levels in these situations the feedwater flow is routed via smaller nozzles that can easier withstand thermal transients. 

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