What Are the Different Types of Spring Mechanical Seals

Single Spring Mechanical Seals

Single spring mechanical seals feature a single coil spring that provides the necessary sealing force. The spring is typically located behind the stationary sealing face, pushing it against the rotating face to create a tight seal. Single spring seals are known for their simplicity, reliability, and cost-effectiveness, making them a popular choice for many general-purpose applications.

These seals are suitable for a wide range of operating conditions, including moderate temperatures and pressures. They can handle shaft speeds up to 5,000 rpm and are compatible with various fluids, such as water, oils, and mild chemicals. Single spring seals are commonly used in pumps, mixers, and other rotating equipment found in industries like water treatment, chemical processing, and food and beverage production.

Multiple Springs Mechanical Seals

Multiple springs mechanical seals employ two or more coil springs to provide a more balanced and consistent sealing force compared to single spring designs. The springs are evenly distributed around the circumference of the seal, ensuring uniform pressure on the sealing faces. This configuration helps to compensate for any minor misalignments or shaft deflections, resulting in improved sealing performance and longer seal life.

Multiple springs seals are designed to handle more demanding operating conditions than single spring seals. They can withstand higher temperatures and pressures, as well as faster shaft speeds up to 10,000 rpm. These seals are commonly used in applications that require enhanced sealing capability, such as high-pressure pumps, compressors, and turbines in industries like oil and gas, power generation, and petrochemical processing.

Wave Spring Mechanical Seals

Wave spring mechanical seals utilize a unique spring design that consists of a wavy or sinusoidal profile. Unlike traditional coil springs, wave springs provide a nearly constant force over a wide range of deflection, ensuring consistent sealing performance. The compact design of wave springs allows for a smaller seal envelope, making them ideal for space-constrained applications.

Wave spring seals offer several advantages over conventional coil spring designs. They can accommodate larger shaft misalignments and deflections without compromising sealing effectiveness. Additionally, the constant sealing force provided by wave springs helps to minimize wear on the sealing faces, extending seal life. These seals are suitable for high-speed applications up to 15,000 rpm and can handle moderate to high temperatures and pressures.

Metal Bellows Mechanical Seals

Metal bellows mechanical seals feature a thin, flexible metal bellows that replaces the traditional spring mechanism. The bellows is welded to the stationary sealing face and provides the necessary sealing force through its elastic deformation. Metal bellows seals offer excellent sealing performance and are designed to handle extreme operating conditions.

The all-metal construction of these seals makes them resistant to high temperatures, often exceeding 400°C (752°F). They can also withstand high pressures and aggressive chemicals that would deteriorate elastomeric seals. Metal bellows seals are commonly used in demanding applications such as high-temperature pumps, steam turbines, and chemical reactors in industries like refining, power generation, and chemical processing.

Difference Between Types of Spring Mechanical Seals

Seal Type	Spring Design	Temperature Range	Pressure Range	Speed Limit	Key Features
Single Spring	Single coil spring	Moderate	Moderate	Up to 5,000 rpm	Simple, reliable, cost-effective
Multiple Springs	Two or more coil springs	Moderate to high	Moderate to high	Up to 10,000 rpm	Balanced sealing force, improved performance
Wave Spring	Wavy or sinusoidal profile	Moderate to high	Moderate to high	Up to 15,000 rpm	Constant force, compact design
Metal Bellows	Thin, flexible metal bellows	High (>400°C/752°F)	High	Varies	Extreme temperature and pressure resistance