How to properly measure a mechanical seal in a pump

You will need a caliper to take seal measurements.

A mechanical seal usually consists of two parts:

• Part with spring (movable), mounted on the shaft.
• Fixed ring, which is taken out of the pump housing (they often forget to pull it out, there are two of them in double seals). Fixed rings of different types and sizes can be attached to the same type of moving parts, so it is necessary to measure them. The seal marking on the movable part does not apply to the fixed ring.

There are seals (often put on motor pumps) when the fixed part comes with a spring, for example, Type R-6A, R-6b, R-6bg, R-6C, R-6sb / R-SB.

1. First of all measure shaft diameter. It is advisable to measure the shaft itself, but if it is not possible, then the inner diameter of the seal is at the narrowest point. In this case, the removed size should be slightly smaller than the shaft diameter, since the seal should fit snugly on the shaft.
2. Measure the seat for a fixed ring or the outer diameter of the ring itself, but be sure to with elastic band (sometimes they also forget to remove the elastic band from the case, and measure the graphite itself).
3. Measure the height of the fixed ring from the friction pair to the top of the rubber band.
4. Take the part with the spring and press it almost to the end. Measure the length. This measurement will not show the exact working length, but there will be a rough understanding.
5. Write down the specified dimensions, and you also need to determine the environment in which the seal operates and its temperature.

This data will help you quickly and correctly select a mechanical seal from the BTS Engineering range on the website.

How to choose the right mechanical seal on the site

1. According to appearance of the seal we are trying to determine the type from the catalog on the site. There are mechanical seals that are visually similar to each other, but with different sizes. In this case, you need to carefully check the dimensions of each type to the maximum match with the sample. Drawings for each type of mechanical seal are available on the website.
2. Pre-measure shaft diameter d1 at the place where the mechanical seal is installed. If it is not possible to do this, we measure the inner diameter of the seal at the narrowest point along the elastic band. The removed size should be slightly smaller than the shaft diameter, as the seal fits snugly against the shaft.
3. The part with the spring is pressed almost to the end. Measuring working length L3. This measurement will not be perfectly accurate, but it will provide an approximate understanding of the length.
4. Measuring outer diameter of the fixed ring D7, be sure to use an elastic band (sometimes they also forget to remove the elastic band from the case). If the ring is completely broken, measure the fitting diameter of the hole in the lid where the ring is mounted.
5. Defining a working page fixed ring height L4 - from the friction pair to the top of the elastic band.
6. Using the appearance, dimensions D7 and L4, we define fixed ring type according to the size tables (G6 or G60, G4 or G9, NG, etc.). All drawings show the dimensions with the elastic band on.
7. In accordance with the chemical resistance table, we select the necessary parameters mechanical sealing materials. At the same time, we take into account the liquid in contact with the seal, its temperature and the presence of solid parts.

If any of the above points cause some difficulties in the selection, please call or email us – and we will always be happy to help you choose the mechanical seal that best suits the needs and working conditions of your equipment.