When shopping for lip seals, you may come across single and double lip seals. All lip seals are ring-shaped seals that protect against leaks. They are commonly used around rotating shafts where they fill the open space and prevent fluids or gases from leaking.
They are known as “lip seals” because they feature a grooved lip at the bottom. This grooved lip allows for a more secure fit. So, what’s the difference between single and double lip seals?
What Are Single Lip Seals?
Single lip seals are characterized by a single sealing edge. When placed around a rotating shaft, this sealing edge will create a barrier. Fluids or gases won’t be able to penetrate the sealing edge.
What Is a Double Lip Seal?
Double lip seals, as you may have guessed, have two sealing edges. They feature a similar design as their single lip counterparts. Rather than one sealing edge, though, double lip seals have two sealing edges. This extra sealing edge provides additional protection against leaks and external contaminants, including dust, dirt and moisture.
Differences Between Single and Double Lip Seals
While they are both ring-shaped seals that protect against leaks, single and double lip seals aren’t the same. Single lip seals feature a single sealing edge, whereas double lip seals feature two sealing edges.
Single lip seals are typically used in sealing applications where the primary concern is lubricant retention. Rotating shafts often feature lubricant to reduce friction. Single lip seals are used to contain this lubricant.
Double lip seals can also retain lubricant, but they offer better protection against external contaminants than single lip seals. With double lip seals, the primary sealing edge or lip retains the lubricant, and the secondary sealing edge or lip protects against external contaminants.
Because they only feature one sealing edge, single lip seals typically cost less than double lip seals. They cost less to produce, resulting in a lower cost for consumers.
Single lip seals also offer reduced friction. The sealing edges of seals create friction. With only one sealing edge, as opposed to two, single lip seals offer reduced friction, which translates into lower energy consumption.
One of the primary advantages of double lip seals is their ability to protect against external contaminants. Single lip seals are typically used to retain lubricant or other fluids. They feature a single sealing edge that prevents lubricants and fluids from leaking out of a rotating shaft. Double lip seals, on the other hand, are typically used to protect against the intrusion of external contaminants. They can still retain lubricants and other fluids, but double lip seals also prevent external contaminants from reaching a rotating shaft.