A non-rising stem (NRS) gate valve is a type of valve where the handwheel and stem stay in a fixed position. The stem turns in place. The gate inside moves up or down. This design makes the valve compact. It is a good choice for places with limited space.
How It Works
Unlike a rising stem gate valve, the stem does not move up. The NRS valve has a threaded stem. The gate has a matching internal thread. When you turn the handwheel, the stem rotates. This rotational motion moves the gate. The gate moves up to open the valve. It moves down to close it. The stem stays put. This is a simple and effective mechanism.
Key Benefits
NRS gate valves offer several benefits. They are space-efficient. The stem does not extend, which saves vertical space. This is helpful for underground or tight areas. The stem is protected from damage. It stays inside the valve body. This prevents exposure to dust or moisture. Installation is cost-effective. You do not need extra room. They are also reliable for a tight shutoff. This makes them good for water and fire systems.
Typical Applications
NRS gate valves are used in many places. They are often found in municipal water lines. These are usually buried underground. They are also used in fire protection systems. Marine and shipbuilding projects use them. So do industrial pipes with height limits. AWWA C509/C515 standards prefer NRS gate valves for buried use.
Limitations
NRS valves have some drawbacks. The stem threads can wear out. They are in contact with the fluid. This can lead to corrosion. It is hard to know the valve’s position. You cannot tell if it is open or closed. There is no visible indicator. These valves are not for throttling. They are best for full open or full closed use. They do not regulate flow well.
Post time: Aug-20-2025