What is the purpose of using backup rings with O-rings in hydraulic systems above 1,500 PSI?

Using backup rings with O-rings in hydraulic systems, especially in applications where pressure exceeds 1,500 PSI, is critical for maintaining the integrity of the seal under high-pressure conditions. The primary purpose of backup rings is to prevent the O-ring from being extruded into the gap between the surfaces it is sealing during operation.

Under high pressure, the O-ring can experience significant forces that may cause it to deform and push out of its intended sealing position. This can lead to leakage and failure of the seal. Backup rings provide additional support and create a barrier that helps maintain the O-ring's position, ensuring it remains effective in sealing against hydraulic fluids.

While backup rings may have side benefits related to friction and overall system performance, their primary role focuses on preventing the O-ring from escalating into the sealing gap, significantly enhancing the reliability of hydraulic systems operating under high pressure.