Square Buna O-Ring cords are used in sealing applications where a standard circular cross-section O-Ring may not be suitable. The square profile can offer additional sealing surface area in comparison to round O-Rings, making them a suitable choice for certain static (non-moving) applications. They can also be used when the sealing groove has a square or rectangular shape.
A key advantage of O-Ring cord is that it can be cut to the exact length required and joined to make a custom size O-Ring. This is particularly useful for large or non-standard sizes, where a pre-made O-Ring would not be available. However, a joint in an O-Ring is a potential point of failure, so this approach is typically used for less critical applications, or in situations where the operational conditions are not excessively demanding.
Keep in mind that the effectiveness of an O-Ring seal is highly dependent on the application conditions, including pressure, temperature, the type of fluid being sealed, and the mechanical design of the sealing groove. The decision to use a square Buna O-Ring cord, or any other type of O-Ring, should be based on a careful consideration of these factors.