Ball Valve With Drain Port
Figure 1: Ball valve with drain port
Ball valves with a drain port use this feature to drain fluids or debris from the system. They are often used in applications where it is necessary to completely drain the system or remove residual fluid after shutting off the valve. This article explores the features, selection criteria, and applications of ball valves with drain ports.
Table of contents
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What is a ball valve with drain port
A ball valve with a drain port helps release unwanted or excessive fluid from a pipeline. The valve allows for easy draining of the contents of a pipeline or tank without having to remove the entire valve. The valve accomplishes this by one of the following mechanisms:
- Using the handle: Rotating the ball valve by 90 degrees will open or close the valve. If the handle is perpendicular to the pipe, the inlet port is closed, and the outlet port is vented to the environment via the drain port.
- Using a drain tap: Certain ball valve models have a separate tap to operate the drain port. The valve can be closed using its handle, and the tap is opened to release residual fluid from the drain port that is connected to the outlet port. However, ensure the valve is completely closed before opening the drain port to avoid any unintended leakage or discharge of fluid.
A ball valve's drain port is typically smaller than the main valve port, so the residual fluid may take some time to drain out completely.
Applications
A ball valve with a drain port is typically used under two circumstances:
- Depressurize compressed air systems: When the handle is perpendicular to the pipe, the inlet port is closed, and the valve depressurizes the piping system through the venting borehole. As a result, the pressure inside the piping system is reduced to a safe level, making it easier and safer to carry out maintenance or repair work on the system.
- Removing water from a line: Water left in the spigot or valve can freeze and expand during winter, which can cause the pipes to burst and result in costly damage. To winterize a residential outdoor spigot using an indoor ball valve with a drain port, first, turn off the valve to stop water flow to the spigot. Then, open the spigot to allow any remaining water in the line to drain out. Finally, open the drain port on the ball valve to drain any water trapped inside the valve.
Read our ball valve applications article for for details on the various applications of ball valves.
Selection criteria
While ball valves with drains can be used for normal shutoff applications, they may not always be necessary or cost-effective for all applications.
- Standard ball valves are often less expensive and simpler in design, making them suitable for applications where the added features of a ball valve with a drain are not needed.
- A ball valve with a drain port has an additional opening that can increase the risk of leaks or contamination if improperly used.
The normal ball valve selection process is the same for ball valves with a drain (connection ports, material, temperature/pressure). Additional criteria to consider are:
- Drain port size: The drain port should be large enough to accommodate the expected flow rate of the drained media from the system. If the flow rate is too high for the size of the drain port, it can lead to backpressure or other issues that can compromise the effectiveness of the valve. Also, if the valve is installed in a tight space or in a location where access is limited, a smaller drain port may be required to ensure the valve can be properly installed and maintained.
- Working of the drain port: Choose an appropriate ball valve depending on whether the valve handle or a separate tap operates the drain port.
- End connections: The end connections of the valve must match the type of pipes being used in the system. The most common end connections are threaded, flanged, and welded. Read our article on ball valve connection types for more information.
- Accessories: The drain port of a ball valve can be fitted with various accessories, like a hose connection or a cap, to prevent debris from entering the valve when it is not in use.
FAQs
What is a ball valve with a drain port used for?
A ball valve with a drain port controls fluid flow in a pipeline while providing a convenient way to drain the system.
What are the benefits of using a ball valve with a drain port?
The main benefit of using a ball valve with a drain port is that it provides a convenient way to drain the system without additional valves or fittings. Additionally, it allows for easy maintenance and repair of the system.