Single Spring Mechanical Seals

Single spring mechanical seals are versatile and widely used sealing solutions in pumps and other rotating equipment, known for their simple design, compact size, and cost-effectiveness. They use a single, strong coil spring to provide the necessary axial force to keep the primary sealing faces in contact, compensating for wear and minor shaft misalignment.
Key Features and Benefits
Simple and Compact Design: The straightforward single spring configuration makes these seals mechanically simple, easy to install in limited gland space, and generally more affordable than complex cartridge or multiple-spring designs.
Cost-Effective: Their simple design translates to lower manufacturing costs, making them an economical choice for general-purpose applications.
Versatility: Available in various materials (stainless steel, carbon, ceramics, etc.) and configurations to handle a wide range of fluids, temperatures, and pressures in general industrial uses.
Tolerance for Solids (in certain designs): Some single spring designs, particularly the non-clogging open coil types, are more tolerant of viscous or mildly abrasive fluids compared to seals with multiple, small springs that might clog with debris.
Common Types and Construction
Single spring mechanical seals are typically classified by how the spring is exposed to the process fluid and whether the design is "balanced" for high pressure or "unbalanced" for standard pressure:
Pusher Seals: The most common design, where the secondary sealing element (an O-ring or wedge) is pushed along the shaft by the spring to maintain contact with the primary seal face as wear occurs.
Metal Bellows Seals: In this type, the single coil spring is often placed externally (away from the process fluid) for protection, or the bellows itself acts as the spring/secondary seal combination. They are ideal for high-temperature applications where elastomers might degrade.
Balanced vs. Unbalanced Designs: Unbalanced seals are standard for low-to-moderate pressures, while balanced designs modify the pressure on the seal faces to operate efficiently and with less wear in high-pressure environments.
Applications
Single spring mechanical seals are ideal for general-purpose applications involving clean, non-hazardous fluids:
Water and Wastewater Treatment: Used in a wide range of pumps for handling clean water, treated sewage, and other non-abrasive fluids.
HVAC Systems: Employed in pumps handling hot and cold water for heating and cooling circuits.
General Industrial Use: Found in pumps and mixers across various manufacturing processes for handling general oils, mild chemicals, and solvents.
Food and Beverage (Specific Designs): Hygienic designs with FDA-compliant materials are available for use in less demanding food processing applications.