Mechanical seal compression amount issue

Non-containerized, sealed cantilever pumps are not allowed. Multi-stage pump double supports are mostly of integrated sealing type ； Older devices do not have integrated sealing; the ring also needs to be removed before data can be measured.

Firstly, your question is too general. Secondly, the compression amount of the seal is a range; there’s no need to specify an exact value for it. Once the sealing disc is installed, you can immediately tell whether the compression amount is too large or too small. Generally, larger springs result in greater compression, while smaller springs (or multiple springs) usually require only about 3 millimeters of compression. If the pressure is high, then 4 millimeters should be used

The question is too general; it depends on what type of pump and seal is used

Generally, it has to be removed for measurement in order to determine the compression amount; it can also be done after the pump’s cover has been installed. Without installing an impeller, one person uses tools to press down on the shaft sleeve firmly, while another person uses a depth gauge to measure it, allowing for an approximate determination of the compression amount.

After removing the mechanical seal gland and when the spring returns to its normal state, measure the distance from the moving ring at the top of the spring to the bottom; then measure the distance from the stationary ring at the bottom of the spring. The difference between these two distances represents the compression amount.

You can also calculate the compression amount indirectly; generally, the force is 0.25 multiplied by the contact area, and then the spring can be determined based on that force

There should be specialized measuring tools; if manual measurement is used, the height can only be measured in its natural state, by pressing down with the hand before taking the measurement. The difference between these two values represents the degree of compression

Theoretically, when the pump is in operation, the spring of a non-equilibrium mechanical seal generally plays little role; the pressure within the sealing chamber itself is sufficient to keep the two sealing surfaces in contact, with only a slight degree of compression being required. Sometimes, leakage occurs due to insufficient spring pressure because the machining dimensions of the rotating/stationary ring seats are not up to standard; for example, if the radial dimension of the stationary ring seal is too loose, it is necessary to increase the spring compression so that the auxiliary seal can be compressed and deformed to provide a sealing effect. Many years ago, an experiment was conducted: efforts were made to place the spring of the mechanical seal outside the device, and the pump chamber was pressurized to over 10 kg of pressure; under such conditions, the seal was under such stress that the pump could hardly be rotated by hand. Once the spring was removed, however, there was no leakage at all.

You are referring to the spring compression amount, not the mechanical seal compression amount

It seems that for single-face mechanical seals, it’s possible to calculate the compression amount by measuring just one dimension, provided sufficient data is available