Poppet valve

Fig. 36. (a) Single poppet valve (b) combined inlet—outlet axial plate valve. 

G. E. Hundleby, Development of a Poppet-Valved Two-Stroke Engine—The Flagship Concept, SAE 900802, Society of Automotive Engineers, Warrendale, Pa., 1990. 

The poppet valve (see Figure 3-13) consists of multiple, same-size ports and sealing elements. The advantage of the valve is that has a high flow efficiency due to the high lift used and the streamlined shape of the sealing element. The disadvantage is that the valve is not tolerant of... 

Figure 3 13. Cutaway of a poppet valve. Courtesy of Dresser-Rand)...

Poppet valves are typically used for low compression ratio applications, such as pipeline booster compressors. As the pressure differential increases across each of the individual poppets, they lift and allow gas to pass through the flow openings in the stop plate. 

Figure 11-16. Cut-away view of poppet valve. [Couflesy of Dresser-Rand Company.)...

A variety of fast-acting valves are available, inclnding slide gate, flap (bnt-terfly), and float (poppet) valves. Slide gate and flap type valves are actn-ated (closed) npon a signal from a detector (sensor) in the pipeline between two items of interconnected process eqnipment. The detector sends a... 

Bauer has studied losses in compressor cylinder performance associated with valve losses as they relate to overall efficiency. Bunn examines poppet valves for retrofitting cylinders. 

A pendulum hangs in a conical grooved bore. A spring tends to move the pendulum and the poppet valve upwards when the circulation stops. If the tool... 

When the circulation is started, the poppet valve travels slowly down, generating one pressure pulse when passing each restriction. The measurement range in the standard tool is of 2.5° (also 7° ranges, 1° increments, max. 17°). 

Figure 10.34 Schematics of a poppet-style nonreturn valve a) full view, and b) a cutaway view showing the flow paths for the poppet valve in the closed position. The poppet valve is forced forward during plastication to allow flow from the screw channels to the tip. The poppet is forced back during the injection step, preventing polymer from flowing back into the screw channels (QSO valve schematic courtesy of Jeffrey A. Kuhman of Glycon Corporation)...

Figure 5.20 Poppet valves of PTFE for high purity applioations. (Courtesy Mace Products and DuPont Companies.)...

VALVE, POPPET - A device that controls the rate of flow of fluid in a line or opens or shuts of the flow of fluid completely. When open, the sealing surface of the valve is moved away from a seat. When closed, the sealing surface contacts the seat to shut of the flow. Poppet valves are used extensively as pneumatic controls and as intake and exhaust valves in most internal combustion engines. 

Since the columns must be interchangeable, the full set of connections must be provided on them all, and this involves a fairly extensive set of control valves. Since the start of one feed corresponds precisely with the cessation of another, it is convenient to employ multi-port valves, and various mechanical designs are available. These may be manually operated or may be driven by motors controlled by time switches if operating on a constant time cycle and with constant flow rates. A poppet valve assembly of this type is shown in Fig. 3.5. If each cycle must be unique to cope with variations of feed concentrations, etc., it is possible in some processes to control the motorized valve assemblies by means of automatic analysers on the effluent, eluent and wash streams. Instrumentation of this type can only be installed after very thorough development trials with process solutions under a wide variety of anticipated operating conditions, if reliable operating results are to be obtained. 

The uranium trioxide feed passes to the reduction reactor by means of a reciprocating feeder. The dioxide product is metered in a suitable vessel after withdrawal from the reactor. A special type of poppet valve is used on these lines conveying solids. 

The complexity of injection molding equipment is illustrated with the choice of nonreturn valves which prevent flow of melt back to the screw. There are two basic types ball check, and ring check, and their variations. Valve selection extends further, to include general-purpose three-piece, four-piece, and five-piece valves free-flow valves castle valves smear valves and spring (poppet) valves [12]. 

For example, for one machine equipped with plastic poppet valves (i.e., compressor cylinder valves designed for high capacity but low compression ratios), valve losses as measured by a Beta Scan were reduced from 25% to 10% when the compression ratio was reduced from 1.42 to 1.28. This occurred even though the gas volume moved through the compressor increase by 50%. 

A fixed soot blower, shown in Exhibit 7-26, is mounted directly on the convection section wall and is hard-piped as shown. A retractable soot blower, illustrated in Exhibit 7-27, allows the lance to be removed from the convection. seaion during operation. Some of the principal components are the support channel, the gear-driven carriage, the poppet valve (used to control the flow of the cleaning medium), and the lance with nozzles. Exhibit 7-28 depicts a soot blower in operation. As the lance enters the heater, the blowing medium cuts a path through the deposits until the lance reaches its apex. The lance then reverses rotation and is indexed so that on the retraction path it cleans surfaces not covered on insertion. The reversed rotation and indexing allow the soot blower to peel and strip all deposits efficiently and with less chance of heater tube erosion. 

Figure 12.3 Poppet valve liquid injector. Drawing by M. Mackay, 1988, Rapra Technology)...

Figure 12.4 Arrangement of poppet valve injectors to avoid slip layers.

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