Are all globe valves designed to lower to upper?
The lower to upper design is for small flow resistance and saving effort when opening valves. Besides, when it's closed, gasket between body and bonnet and packing around stem don't bear force, which can extend service life and reduce probability of leakage.
Usually, globe valves are designed to lower to upper, but in some case, it can be upper to lower design:
Usually, globe valves are designed to lower to upper, but in some case, it can be upper to lower design:
- 1. High pressure valves with diameter more than 100mm.
Due to poor sealing performance of large diameter valve, with upper to lower, the medium pressure works on the upper of disc when globe valve is closed, which can increase its sealing performance.
- 2. Two series globe valves connected on the bypass pipe, the second one is required to be upper to lower.
In order to prevent gasket and packing from being affected by medium and temperature for a long time, it requires the installation direction of the second valve to be upper to lower.
- 3. Boiler exhausts and vents globe valves.
Boiler exhausts and vents globe valves are only used during start-up. It's of low frequency of opening and closing, but the working fluid is often lost due to lack of tightness. For this reason, some power plant use the upper to lower design globe valves to improve tightness.
