globe valves-tuopu
[author：topsvalve] [date：10-10-23]
[heat：]
Globe valves are closmg-down valves m which the closure member is moved squarely on and off the seat. It is customary to refer to the closuremember as a disc, urespective of its shape.
By this mode of disc travel, the seat opening varies in direct proportion to the travel of the disc. This proportional relationship between valve opening and disc travel is ideally suited for duties involving regulation of f:low rate.hiaddition, the seating load of globe valves can be positively controlled by a screwed stem, and the disc moves with little or no friction onto the seat, dependmg on the design of seat and disc.The sealing capacity of these valves is therefore potentially high. On the debit side, the seatings may trap solids, which travel in the flowingfluid.
Globe valves may, of course, be used also for on-off duty, provided the flow resistance from the tortuous flow passage of these valves can be accepted. Some globe valves are also designed for low flow resistance for use in on-off duty. Also, if the valve has to be opened and closed frequently, globe valves are ideally suited because of the short travel of the disc between the open and closed positions, ttnd the inherent robustness of the seatings to the openmg and closmg movements.
Globe valves may therefore be used for most duties encountered in fluid handlmg systems. This wide range of duties has led to the development of numerous variations of globe valves designed to meet a particular duty at the lowest cost. The valves shown in Figure 3-2 through Figure 3-11 are representative of the many variations that are commonly used in pipelines for the controlof flow. Those shown in Figure 3-12 through Figure 3-14 are specialty valves, which are designed to meet a special duty, as described in the captions of these illustrations.
An inspection of these illustrations shows numerous variations in design detail. These are discussed in the following section.