What’s the difference between a Parbak rubber backup ring and a PTFE backup ring?
PTFE backup rings come in three varieties – solid, spiral wound, and split. Solid PTFE backup rings are extremely difficult to install. Since PTFE is not resilient, the backup rings must be “reformed” after being installed in the groove to return them to their original dimensions. Spiral wound and split PTFE backup rings overcome this problem – they can be opened slightly during installation without deforming them. However, they leave a sharp edge that can damage the O-ring. Parbak rubber backup rings eliminate all of these problems. Because they are rubber, they can be stretched during installation and will snap back into position. Since they have no sharp edges, they cannot damage the seal during use. Please note that Parbak backup rings are not intended to provide a seal themselves – they provide additional support in high pressure applications.
