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All you need to know about Single Spring Mechanical Seals


Mechanical seals have a long history that dates back to the early 20th century. They have been used in the processing and manufacturing industries to join machines and systems together so as to avoid leakages. Technically, there are different types and designs of mechanical seals. Their effectiveness often depends on the compression level, the design and make of the seal. The applications and procedure of handling the mechanical seals also affect the overall results.

Single spring mechanical seals have a single coil spring design and are used mostly for self-cleaning and non-clogging operations. They have higher resistance to pressure & heat and guarantee the best of long-term usage.

Single spring mechanical seals also come with a simple design. It has few parts and can be assembled or dismantled with ease. To take a variety of applications, this type of mechanical seal is available in two distinct types; Balanced and unbalanced designs.

Single spring varieties


There are three main varieties of this type of mechanical seals. All of them have a single spring and can be identified easily from the double mechanical seals. Depending on where you’ll buy your single spring seal, the naming can vary but the product will just remain the same. The three types are Type C, Type D, and Type E; other suppliers/ manufacturers would name these products as; Type 21, Type 2 and Type 1 respectively.




Single spring mechanical seals are used for a number of applications which include centrifugal pump application and rotary pump application. Some of the fluids supported include but not limited to; abrasive, viscous, crystallizing, non-corrosive and solidifying slurry.


Specification of each variety and their advantages


Type E


This type features a single coil spring with a large head on top of the spring. It has rubber bellows to seal the shaft and the rotating face can be made of different materials. Type E seals can either have stamped metals parts or machined parts. The machined or industrial seal is more expensive, durable and reliable as compared to their stamped counterparts. It also comes in both the balanced and unbalanced types - all fully repairable.


Type D


The Type D single spring seal has a slightly different design with the head sitting inside of the spring. This is intentionally designed so as to reduce the working length compared to that of type E. Type D like the other models have rubber bellows with a carbon rotating face. The coil spring fits over the retainer and both the balanced and unbalanced types are available- all fully repairable. The short working length is highly reliable and accommodating; it guarantees an enhanced seal capability, performance & life.


Type C


The Type C was developed as a combination of both the Type E and Type D. The head sits half inside and half above the spring. It features a single coil spring, rubber bellows, stamped metal parts, and carbon rotating face. The stamped parts are relatively cheaper hence this Type C is usually affordable. With a short operating height and complex design, it’s unbalanced and has limited repairs.


Overall advantages and disadvantages of single spring mechanical seals


Single spring mechanical seals are the most common and widely used types of mechanical seals. They are quite versatile, affordable and efficient compared to the double mechanical seals. This is, however, not to say that they don’t have their unique disadvantages.




They are common with many machines and most of them are repairable. This means that finding repair parts and replacement options is a bit easy.


The pumped liquid used with most single mechanical seals is cool and stable. They have good lubricity and doesn’t contain broke-down or rough solids.


It’s one of the most conservative gadgets among the other mechanical seals since it has the least number of parts.


It’s versatile and quite efficient. If the pumped liquid lacks the appropriate properties of a fixing liquid, you can comfortably add a helper liquid over the seal confront- and you’ll be good to go.




One of the devastating drawbacks of the single mechanical seals is that if the seal spills over, it can be hard to handle and resolve the problem. A disturbance on the framework, for example, can cause glimmering of the fluid.

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