[Technical FAQ] What is the cavity relief hole in a valve ball?

The cavity relief hole in a valve ball, also known as a vented ball, upstream relief hole, or downstream relief hole, is a critical feature for pressure relief in ball valves. It allows for the release of pressure buildup caused by temperature fluctuations, ensuring the safe operation of the valve and system.

The cavity relief hole in a valve ball, known by various names such as vented ball, upstream relief hole, or downstream relief hole, plays a crucial role in ensuring the safe and efficient operation of ball valves, particularly in industries where temperature fluctuations can lead to dangerous pressure buildup.

In a vented ball design, pressure relief holes are drilled into the sphere of the ball valve. These holes provide a pathway for the release of pressure that can occur due to changes in temperature. Without this feature, the increase in cavity pressure could lead to potentially hazardous situations, especially in industries dealing with cryogenics, chlorine, hydrogen peroxide, and heat transfer fluids.

The upstream relief hole, if present, allows pressure to bypass the upstream seat and relieves expansion pressure in the ball and body cavity of a closed valve. This design effectively turns the valve into a uni-directional valve, ensuring that pressure relief occurs toward the direction of the high-pressure source.

Overall, the cavity relief hole, whether referred to as a vented ball, upstream relief hole, or downstream relief hole, is a critical feature in ball valves. It ensures the safety and efficiency of industrial processes by allowing for the controlled release of pressure buildup caused by temperature fluctuations.