O-rings have been used for many years to energize u-cup style seals with great success. Ever-increasing application demands in terms of pressure and temperature, however, have made o-ring energizers less practical than other (metal) type energizers. The primary problem with using o-rings in these HP-HT applications is the fact that the o-ring, over time, will take a compression set and lose its ability to energize the seal effectively. The illustrations to the right demonstrate this phenomenon. Seal 1 shows the o-ring as installed while Seal 2 shows the o-ring after it has been in service. The top and bottom surfaces of the o-ring are flattened out and the o-ring can no longer energize the seal. This will result in seal leakage.
Maudlin’s metal spring energizers however do not suffer from compression set even at the highest of application temperatures and pressures. The springs are designed to be installed short of their yield points and expand to keep the seals in contact with the hardware over a wide range of applications. This means that pressure cycles, multiple start/stop procedures as well as long storage times can all be handled without the worry of compression set.
Another, less know problem with o-ring energizers in high-pressure applications is their tendency to trap pressure behind the o-ring and get “blown out” of the spring groove. Maudlin’s spring energizers are designed to be non-pressure holding so that once installed they stay in place and only function to energize the seal.