What is PTFE packing?
PTFE valve packing is one of the most commonly used types of valve packing. It is used to seal valve stems and other parts of liquid-transporting machines. PTFE has excellent resistance to several aggressive chemicals and can safely come in contact with potable water.
What is Valve stem packing?
Valve stem packing is a self forming packing material. It forms to all surfaces and irregularities such as scratches and pits. It is made from 100% virgin PTFE and has a high tensile strength. The products are self lubricating and eliminates valve stem wear.
What is live load packing?
Live-Loaded packing is a methodology for maintaining steady pressure on a specific gland force that is caused by thermal cycling, pressure surges, packing relaxation, wear or extrusion. EGC has developed a data sheet for all valves providing assistance in accumulating the right dimensions and company data.
What is graphite packing?
Graphite packing is a highly resistant sealant used in systems with valves, faucets, and stuffing boxes, as well as other machines with watertight mechanical parts. It can be applied either to static valve stems or to moving joints.
Why do valve packs leak?
Valve packing is a component in a valve that forms pressure seal between the inside of the valve and the outside of the valve, keeping the process fluid from leaking out. Over time, the packing will wear in, relax, or loosen up with process temperature, or even seasonal ambient temperatures, and begin to leak.
What is a single PTFE V-ring valve?
The single PTFE V-ring arrangement uses a coil spring, as in the easy-e valves, and meets the 100 ppmv criteria, assuming that the pressure does not exceed 20.7 bar (300 psi) and the temperature is between -18C and 93C (0F and 200F). This packing arrangement offers very good seal performance with the lowest packing friction.
Does packing friction affect packing selection?
In the past, packing selection was primarily based on process temperature; that is, PTFE was selected for temperatures below 232C (450F) and graphite was selected for temperatures above 232C (450F). Considerations now include the effect of packing friction on process control, hysteresis, seal quality, and cycle life.
What is the difference between graphite packing and PTFE packing?
Compared to PTFE packing systems, graphite packingsystems operate at higher stress levels and have higherfriction values for a given level of sealing. To combatthis, most graphite systems incorporate a smallamount of PTFE which acts primarily as a lubricant.