The essential principle of globe valve operation is the perpendicular movement of the disk away from the seat. Conventional globe valves may be used for isolation service. Although these valves exhibit slightly higher pressure drops than straight through valves (e.g., gate, plug, ball, etc.), they may be used where the pressure drop through the valve is not a controlling factor.
Globe valves are extensively employed to control flow. The range of flow control, pressure drop and duty must be considered in the design of the valve to avert premature failure and to assure satisfactory service. Valves subjected to high differential pressure throttling service require a specially designed valve trim.
The practical size limit for these valves is NPS 12. Large valves would require that enormous forces be exerted on the stem to open or close the valve under pressure.
Globe valves are extensively employed to control flow. The range of flow control, pressure drop and duty must be considered in the design of the valve to avert premature failure and to assure satisfactory service. Valves subjected to high differential pressure throttling service require a specially designed valve trim. Maintenance of globe valves is relatively easy since the disks and seats are readily refurbished or replaced. This makes globe valves particularly suitable for services which require frequent valve maintenance. Where valves are operated manually, the shorter disk travel offers advantages in saving operator time, especially if the valves are adjusted frequently.
Advantage and disadvantage of Globe Valve
The main advantage of this arrangement is that a globe valve opens more rapidly than a gate valve as the disc only needs to move a small distance from its seat to allow full flow. This is an advantage when there is frequent operation of the valve.
The disadvantage is that the fluid has to change course, increasing the resistance to flow and generating turbulence. This results in a higher pressure drop across a globe valve than a gate valve.