U Cup Seals :
The Loaded Lip U-Cup is a very versatile seal because it can be used as a rod seal or piston seal. The energizer ensures constant pressure on the sealing lips. it is considered a multipurpose seal and is designed for significantly improved performance
Sam Engineers offers three styles of the Loaded lip U-Cup Seal :
- Deep Base, a
- "B" Style
In addition, we can supply Loaded Lip U-Cups in various types of elastomers to meet your specific requirements.
The Standard deign is usually symmetrical in cross section in which the height of the U-Cups is the same as the cross section.
The Deep Base (DB) U-Cup is the same basic design as the standard style except the height is taller
The "B" Style has a back beveled lip and generally the same height as the deep base, but functions with more lip interference. This design helps to ensure optimum sealing function. This style is particularly useful in high pressure conditions. In addition, the design of the "B" style loaded Lip U-Cup combines ease of installation with rugged construction for highly effective seal in heavy duty applications.
This series of sealants can be designed into the original equipment for significantly longer life than some of the other types of seals.
Design & Function :
The pressure range for this packing is from vacuum to 5,000 psi, based on machine parts being within J.I.C. Standard tolerance and the type of elastomer from which the seal is made. Also the temperature range is dependent upon the type of elastomer from which the seal is made.
The energizer keeps the lips of the seal pressed against the sealing surfaces thus allowing the Loaded Lip U-Cup to seal under low pressure.
You will notice from the chart below that the groove axial length is a few thousandths of an inch more than the height of the Loaded Lip U-Cup. This allows the seal to float and helps it seal under slight side loads.
Loaded Lip U-Cups give longer wear life because of a larger lip contact area than the live contact area of other conventional packings.
Although the loaded Lip U-Cups have exceptional resistance to abrasion, no seal should be expected to give long service when operating on poorly finished or pitted surfaces, scored cylinders or rods. The finish on both the rod and cylinder should be 10 rms to 16 rms. This finish not only smooth enough to keep the packing from tearing, it allows seepage and thus lubricates the seal.
Additionally there are other considerations when designing Loaded Lip U-Cups. Following are some cases.
In the back-to-back piston application as in a double acting piston, there is a need for the energizer to be removed to prevent pressure forming in between the seals. For these situations, it is recommended that the "B" style Loaded Lip U-Cup be used.