In submersible pumps, mechanical seals are critical for preventing water leakage and ensuring stable operation. At the core of the mechanical seal are two key components: the rotary ring (dynamic ring) and the stationary ring (static ring). The materials used for these sealing surfaces directly impact the pump’s performance, durability, and maintenance cycle.

This article explains the most common materials used in submersible pump seal rings, their advantages and disadvantages, and how to choose the right combination for different working environments.

What Are Rotary and Stationary Rings in a Mechanical Seal?

A mechanical seal in a submersible pump typically consists of a rotating ring (rotary ring) mounted on the shaft and a fixed ring (stationary ring) attached to the pump housing. These two rings are in close contact, forming a tight sealing surface that prevents fluid from leaking out while the pump is running.

Common Seal Ring Materials: Pros and Cons

1. Carbon (Graphite)

Pros:

• Excellent self-lubrication

• Low friction coefficient

• High temperature and corrosion resistance

• Good sealing performance

Cons:

• Brittle and prone to breakage

• Not ideal for fluids containing abrasive particles

Typical Use: 

• Often used for stationary rings, sometimes also for rotary rings

2. Silicon Carbide (SiC)

Pros:

• Extremely hard and wear-resistant

• Excellent chemical resistance (acid/alkali)

• High thermal conductivity for better heat dissipation

• Ideal for high-speed and high-temperature conditions

Cons:

• Brittle; can be damaged by mechanical shock

• Higher cost

Typical Use: 

• Used for both rotary and stationary rings in demanding applications

3. Tungsten Carbide (WC)

Pros:

• Very high hardness and mechanical strength

• Resistant to abrasion and impact

• Long service life, even in harsh conditions

Cons:

• Heavy and expensive

• It may not resist corrosion as well in acidic environments

Typical Use: 

• Preferred for rotary rings in abrasive or high-pressure applications

Recommended Material Pairings by Application

Choosing the right combination of seal ring materials is essential to match the specific application conditions:

How to Choose Seal Ring Materials for Submersible Pumps

Here are a few practical tips when selecting seal ring materials:

1. Match the Medium

• Clean water or light chemicals: Carbon + Tungsten Carbide

• Acidic/alkaline fluids: Silicon Carbide + Silicon Carbide

• Sandy or particle-laden water: Tungsten Carbide + Carbon or SiC

2. Consider Working Conditions

• High-speed, high-temperature: Favor materials like Silicon Carbide

• Intermittent household use: Lower-cost combinations are usually sufficient

3. Balance Performance and Cost

• While Silicon Carbide offers excellent performance, it is more expensive and sensitive to installation errors.

• Carbon offers great sealing at a lower cost but is best suited for less abrasive environments.

Conclusion

Choosing the right seal ring materials for submersible pumps is key to achieving long-term performance and reliability. Each material has its strengths and weaknesses, and selecting the appropriate combination depends on the fluid type, pump environment, and application frequency.

For reliable submersible pumps with premium seal materials, consider STREAM Submersible Pumps — available in a wide range of models and customizable configurations to meet domestic, agricultural, and industrial needs.