Definition of globe valve：
The opening and closing member (valve new) driven by the valve stem, along the valve seat (sealing surface) axis to do linear lifting movement of the valve is called a globe valve.
Globe valve is generally driven by the drive parts (handwheel, stem, valve body, valve cover, valve flap (closure) and packing assembly, and other major components. The handwheel is connected to the valve stem, and the valve flap is driven by the valve stem, so that the valve flap moves reciprocally along the direction of the valve seat axis, thus making the pipeline connected or cut off.
The globe valve is widely used, mainly for higher pressure and smaller caliber occasions, generally only produced to DN400 (NPS 16), the larger diameter specifications only for special pipelines. For example, a large oxygen pipeline, due to the existence of other valves friction is prone to static fire, so the use of a large-diameter stainless steel globe valve.
The working principle of the globe valve：
Globe valve stem generally do rotary lifting movement, handwheel fixed in the top of the stem. When the handwheel is rotated clockwise, the stem threads rotate down, the valve sealing surface and the valve seat sealing surface in close contact, and the shut-off valve closes; when the handwheel is rotated counterclockwise, the stem threads rotate up, the valve sealing surface and the valve seat sealing surface disengage, the shut-off valve open.
The advantages and disadvantages of the globe valve:
The advantages of the globe valve:
① Compared with the gate valve, the globe valve structure is simpler, usually only one sealing surface on the valve body and valve flap, small sealing area, saving valuable materials, low cost, and therefore better manufacturing process, easy maintenance.
②The seal surface wear and abrasion are light, good sealing. No relative sliding between the valve flap and body sealing surface when opening and closing (except for the conical sealing surface), so the wear and abrasion are not serious, good sealing performance, and long service life.
③Opening height is small, generally only 1/4 of the diameter of the valve seat channel, compact structure, saving installation space.
Disadvantages of globe valve:
①The length of the structure is large.
② large opening and closing torque, opening and closing efforts. When closing, because the direction of movement of the valve flap is opposite to the direction of the medium pressure, the force of the medium must be overcome, so the opening and closing torque is large.
③ large flow resistance. The media channel inside the valve is more tortuous, flow resistance, power consumption, especially in the hydraulic device, this pressure loss is particularly obvious. In all kinds of the cut-off valve the valve flow resistance of the largest.
④ Media flow direction is restricted.
Media flow through the shut-off valve, at the valve seat channel, can only be from the bottom up or down, so the media can only flow in one direction, and can not change the direction of flow.
⑤ In the valve closed, the sealing surface may be trapped between the solid particles in the fluid medium.
⑥It is inconvenient to install.