It was during the Renaissance Period when bedding as we know it today was designed. Whilst the poor continued to sleep on hay-covered platforms, the wealthy owned mattresses stuffed with down and wrapped in luxurious materials. Their four-poster beds were covered in embroidered canopies and contained pull-out trundles for maids and personal valets to sleep on. Mattresses were suspended from the bedframes using ropes or straps. They were covered by smart linen sheets and wool blankets. The beds grew more and more lavish for the most wealthy. They became so expensive they were passed down through the family for generations. Reported to spend most of his day in bed, Louis XIV became so obsessed with bedding that he bought 413 beds for the Palace of Versailles. It is understood that he held court daily from his bed.
Unthinkable in the list of seals are oil seals, which provide a seal against splashing oil. The most important oil seals are used for rotating shafts and valve stem seals. Oil seals are intentionally never completely sealed to lubricate the seals and prevent wear.
In conclusion, oil seals are critical components in ensuring the proper functioning of machinery and equipment. By selecting the right seal based on material, design, size, and operating conditions, users can prevent oil leaks, reduce maintenance costs, and prolong the life of their equipment. With a wide range of options available, it is essential to choose a high-quality seal that meets the specific requirements of the application.
FKM or FPM, which is in well-known brand Viton™, can withstand higher liquid temperatures of up to 180 ˚C. FKM is highly resistant to strong acids and bases, as well as to synthetic oils and greases. Glycol-based oil and grease, however, can also damage FKM.
Ultimately, oil seals are devices that help to exclude dust and dirt, etc., while at all times retaining the lubricant in the piece of equipment.
From this kind of standard immersion testing, one would expect that bisphenol-cured VDF/HFP/TFE fluoroelastomers would not give good service life as oil seals. Similar tests with other elastomers, such as HNBR, silicone, and acrylic rubbers, show less loss of elongation. However, it is found that, in actual service, FKM shaft seals6 have much longer service life than seals of the other elastomers. In a Japanese study of FKM lip seals, rear crankshaft seals from high-mileage automobiles (70,000–280,000 mi ie, 110,000–450,000 km) were collected and examined. No serious oil leakage was found when the seals were removed from the engines. Some deposits were found around the seal lip and on the garter spring holding the lip against the shaft. No surface cracks were found on the seal lip, and only minor crazing on the crankcase side of the flexure portion of the seal in some samples. The seal compositions were not noted, but most were probably VDF/HFP/TFE elastomers with 68–69% fluorine content.
To increase the pressure around the shaft and maintain the seal’s integrity, certain lip seals have an extra spring looped into the flexible rubber part.
