Basically, stop valves are those that completely hinders the flow of liquid through a pipe. They’re especially useful in industrial applications and plumbing to stop water flow (cold or hot) to plumbing fittings, such as faucets, toilets, dishwashers, and icemakers.
Stop valves allow preventive maintenance, such as drain cleaning, filter change, and replacing the entire instrument or design.
They have various types, but the most common are globe valves and gate valves. Both are commonly used in refrigeration systems and piping.
Globe valves are structured with a stem that moves up and down to control the flow inside the valve. They will disrupt flow all the time but will shift into their position fast.
They are linear motion valves and have valve disks that can be completely detached from the flow path, or they can completely close the flow.
During the opening and closing of globe valves, the disks will move perpendicularly to the seat. This mechanism develops the round space between the seat ring and the disk that will slowly shut off as the valves close.
Gate valves are commonly used in various operations that are ideal for both above and underground installations. They only restrict flow when they’re in use, but it takes time for them to shift into position and have high chances of leaking.
Gate valves are structured for fully opened and closed services. They are attached in pipelines and should only be used as confining valves. They must not be used to control or regulate water flow. The procedure of gate valves is done by doing an either clockwise to open (CTO) or clockwise to close (CTC) rotating manner of the stem.
They are commonly used when there is minimal pressure loss and when a free bore is required. When they are entirely open, gate valves do not obstruct the flow, which will result to minimum pressure loss. This structure allows the use of a pipe-cleaning pig.
They are multi-turn valves, which means using them will be done through a threaded stem. The valve has to turn several times, which hinders water hammer results.