Mechanical seal Basic, Summaries of Mechanical Engineering

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Mechanical Seals in the Pump Industry

We will cover this subject in three webinars:

1. Introductory (today)
2. Advanced
3. Installation, service and failure analysis

Shaft Seals For most pumps a decisive element for the quality of the pump during its lifetime is a good and robust shaft seal.

Lubricating film Lubricating film (≈1 μm ) Lubricating film too thick Lubricating film too thin

Lubricating film The six “MUST” of the lubricating film

• be always present
• be stable
• be clean, free of abrasives
• have reasonable viscosity
• have controlled temperature
• have acceptable pressure

Shaft Seal Types Stuffing Box Mechanical Seal

Packing vs Mechanical Seals Packing

• Seals with visible leak
• Constant monitoring for adjustments
• Shaft wear or use sleeve
• Special handling not required
• Low initial cost Mechanical Seals
• Seals with invisible leak
• Minimal monitoring and no maintenance
• Virtually no shaft drag
• Handle with care
• High initial cost

Mechanical seal Anatomy

• The Hardware The essential elements of a mechanical seal:
• The Primary Sealing Element
• The Secondary Sealing Elements

Secondary Sealing Elements The Secondary Sealing Elements

• Dynamic Seal
• Static Seal

Hardware

The Hardware

• Drive Elements
• Load Element
• Adaptive Elements

Mechanical Seal Classification Mechanical seals are typically divided into two categories: by Arrangement and by Design. Mechanical Seals Arrangement Design Single Dual Balance Loading Flexible Head Springs Inside Mounted Pressurized^ Unbalanced^ Pusher^ Rotating^ Mono-Spring Outside Mounted Non pressurized (^) Balanced Non-Pusher (^) Stationary Multi-Spings Wave Spring

Arrangement Classification Single Inside Mounted Single^ Outside^ Mounted Cartridge Seal Dual Tandem (^) Dual Face-to-Face Dual Back-to-Back

Single – Outside Mounted

Shaft Seal Housing Process Fluid Drive Collar Set-Screw Drive Pin Multi-Spring Rotating Ring O-Rings Stationary Ring Static Gasket Seal Gland

Cartridge – Cartridge Seal

Shaft Seal Housing Process Fluid Drive Collar Set-Screw Drive Pin Multi-Spring Rotating Ring O-Rings Stationary Ring Static Gasket Seal Gland Barrier Fluid Seal Sleeve