Ring valves

Ring valves are typically used for slow speed, high pressure process compressors. Instead of individual poppets, these valves use conccntnc rings, which open and close the valve ports. 

Plate valves are typically used for high speed separable compressors. Plate valves are similar to ring valves with the rings connected by ribs. Instead of individual elements opening and closing, all valve ports o[)en and close at the same time. 

Figure 11-77. Cut-away view of ring valve. Courtesy of Dresser-Rand Company.)...

Iron Cylinders, liners, pistons, rings, valves, valve guides, gears, shafts, clutch plates, antifriction bearings, rust... 

Lubricator connection Guide bushing Upper seat ring Valve plug —... 

The rigidity, hardness, and dimensional stability of cemented carbides, coupled with their resistance to abrasion, corrosion, and extreme temperatures, provide superior performance in fluid-handling applications such as seal rings, valve stems and seats, and nozzles. 

Processing PCTFE is by the conventional methods (extrusion, injection, etc.) processing temperatures are high, and any degradation of PCTFE can cause severe corrosion and environmental problems. Applications include wire and cable insulation, electronic flexible printed circuits, packaging material (transparent film and sheet), pharmaceutical industry in particular strip and blister packs for tablets and capsules, etc. In the chemical industry, used as gaskets, 0-rings, valve seats, chemical tank liners, etc. 

Use is made of screw tip valves, popularly called non-return valve, ball check valve, or sliding ring valve. They are used in reciprocating injection and injection blow molding machines (IMM and IBMM) to control the melt flow in one direction (Chapter 4). There is also the smearhead for IMM, IBMM, and extruder. Back flow will not occur... 

Backup ring Seal ring Valve plug... 

The most common cyclic process for thermoplastics is injection molding. Modern machinery is of the reciprocating screw type. In this process, the screw rotates and loads a metered dosage of polymer toward the tip. A ring valve at the tip of the screw prevents backflow during forward movement of the screw during the injection part of the cycle. The molten polymer flows... 

An alternative to the check ring valve is a smear head (Fig. 6.33), which is based on the use of a small clearance in the diameter over significant land length. This design restricts the back flow of the melt during... 

Figure 6.32 Schematic of a combination of a check ring valve and an adapter. ...

The poor corrosion resistance of borides may be partially overcome in composites with SiC if the microstructure allows passive oxidation kinetics. In combination with SiC the borides retain their high electrical and thermal conductivity and thus suitable thermal shock resistance. SiC-TiB2 composites have been extensively developed for wear parts in machinery such as sliding rings, valves, valve seats, roller and ball bearings, plungers, and rocker arm pads. 

Front discharge ball check less expensive than sliding ring valve. 

A screw melt seal or valve, similar to a check ring valve, but designed differently. Uses a roundball to seal off the melt so it does not flow back over the screw flights during the injectirm cycle. 

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