Measurement of a mechanical seal is a systematic process. Sometimes, it is impossible to cross-reference a seal. What should be done to assure that the right seal is received for the pump?

Experts say that it is vital to supply the information as accurately as possible. The two major rotating components of a seal are the spring and seal head.

The seal head should be removed from the spring to measure it accurately. The inside diameter needs to be measured on the back side of the seal head. It is the end that fits towards the spring.

Thus, you will arrive at the seal size diameter. Remember, it is either the sleeve size where the seal fits over or the shaft size.

In the majority of the seals, the front side has a black carbon face which runs against the stationary portion (known as the seat) of the mechanical seal assembly.

Now you need to measure the spring length while it separates from the head of the seal. The next step is to measure the outside diameter and thickness of the seat or stationary.

What is next after finding the size of the seal?

Other than finding out the sizing of the seal, now it is time to know about the material the seal is made from. You are supposed to get the following information as well:

  • Is the rotating seal face made from carbon? If it is black, then it is most likely carbon.
  • The elastomer or rubber part of the seal is made from Nitrile (Buna-N or NBR). The exception is a process where the liquid is either some harsh chemical or high-temperature liquid.
  • The seat or stationary of the seal is made from which metal? Is it some white and hard material? Or is it made from metal?
  • What is the shape of the seat and stationary parts in the mechanical seal you are measuring? Does it contain an O-ring? Or does it have a rubber piece which fits into the seal like a cup? They are called cup mount type and O-ring mount type.

Once you have all the information mentioned above, you will be assured of getting the perfect seal assembly. It will fit right and function correctly.

If it is possible, you can send the entire seal assembly so that the seal supplier can measure it and send the right replacement. However, it can happen if you have a spare seal to run the operations well.

Leak-Pack is ISO 9001:2008 certified company and one of the best mechanical seals suppliers, manufacturers and exporters in India, providing solutions to all types of leakages by manufacturing Mechanical Seals and Sealing Components as per customer’s drawings, samples or requirements. To know more about Mechanical Seal call on +91-(2739) 271592 or email at

Read More: 

  1. Why Mechanical Seal Leak?
  2. What Is A Mechanical Seal In A Pump?

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