Alkali leakage from the pump seal
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Hello everyone. The mechanical seal of the alkali pump in our company keeps leaking alkali (see picture). The pump has a flow rate of 18 cubic liters, a head of 15.6 meters, and a power consumption of 3 kW. The temperature of the alkali is around 40 degrees; the pipelines are equipped with heating systems. The leakage becomes particularly severe in winter. Is there any effective way to solve this problem? Thank you.
Leakage is just a phenomenon; when you carry out maintenance, what material are the sealing surfaces made of (is it cemented carbide against cemented carbide?), what do those sealing surfaces look like – are there any wear marks on them? What type of spring is used in the mechanical seal (a small spring or a large spring)? Is there any issue with the spring such as sticking or loss of elasticity? Are there any particles in the medium? Check whether the sealed flush tube is clogged; the small hole at this flush interface is only 3-4 mm in size, and particles can easily cause blockages. Since the head of your pump is not high, you can enlarge the hole to 6mm. If emergency cold water is available on site, the sealing scheme can be changed to PLAN11+62, with emergency cold water being used later to wash away the leaked alkali and prevent it from crystallizing between the shaft sleeve and the sealing ring.
What is the approximate concentration of the base? Is the severe leakage in winter a sign that it’s approaching saturation~alkali release? If possible, I would recommend using PLAN32 to directly rinse the sealing surface, so as to avoid water splashing around at the site caused by 62~~~
The materials for the stationary and rotating rings must be selected properly, and the sealing compression amount should not be too small; the compression amount of multiple springs can reach around 90% of the total length of those springs
This post was last edited by ali2277 on 2018-2-11 at 10:58. The selection of a mechanical seal for alkali pumps is crucial: it is necessary to ensure that the seal components are in a hard-to-hard contact configuration (alkalis have good self-lubricating properties, which improves wear resistance); large springs should also be used to prevent crystallization, and it is important to ensure that the self-cleaning holes do not get blocked. For pumps used with alkaline liquids, it is best to choose shielded pumps, as they are very durable! It ensures no leaks at the site, while also reducing the workload for workers!
Alkali crystallization causes the spring to lose its elasticity, resulting in alkali leakage. I just want to modify the existing pump so that it doesn’t leak; after all, the cost of replacing the pump is very high.
It is recommended to increase the sealing flush water to improve the service life of the seal.
Is this alkaline solution sodium hydroxide or sodium carbonate? The seal flushing method I use with sodium carbonate works very well; the best record I have is 2 years without having to replace the seal. However, sodium hydroxide does not work well with the same rinsing protocol. I am also looking for a rinsing solution using sodium hydroxide
It is recommended to switch directly to a sealless magnetic pump to solve the problem once and for all
Magnetic pumps can’t solve the issue of alkali liquid precipitation either; the wear on the isolation sleeve due to alkali liquid precipitation occurs very quickly.