Low Closure Force

Compressive Force Load

The simple way to decrease the closure force of an O-ring is to:

(1) Decrease the O-ring cross section: Looking at the Compressive Load tables (listed in the eHandbook) for O-rings, we can compare the values for a .103” cross section to that of a .070” cross section. At 20% squeeze, the range for a .103” cross section is approximately 9 to 18 pounds per linear inch of O-ring. For the same amount of squeeze on a .070” O-ring, the range is roughly 5-18 pounds per linear inch of O-ring circumference. 

(2) Decrease the designed squeeze: For the same example of a .070” cross section, if we decrease the squeeze to 10%, we see the compressive load drops to a range of 2 to 5 pounds per linear inch. 

The challenge many designers have with decreasing the O-ring cross section is that the O-ring groove needs redesigned to accommodate the smaller thickness. Many times it is easier to change the seal than the hardware.

The issue with decreasing the seal compression is that this can compromise the O-ring’s life due to increased compression set. Testing shows the optimum amount of seal compression for static seal is generally in the 25% range.

By dropping much below this suggestion, the seal cross section is not fully energized for optimum resilience. Such a change may be favorable for reducing the load needed to compress or install, but it potentially accelerates compression set in the seal.

There are alternate seal options for reducing the compressive load force including Low durometer O-rings, Hollow Profiles, Lip Seals and Diamond Seals.