Problem of frequent leakage in mechanical seals
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Here’s the situation: Our company has a pump used for pumping liquid alkali, and the fluid in question is a mixture of Na2CO3, NaHCO3, H2O, and NaAOH. The shaft seal often leaks, both internally and externally, and its lifespan is less than half a year. Is it due to an inappropriate design of the shaft seal, or is it because the material used for its components is not suitable? Dear sea friends, please offer some suggestions. Here are some working conditions; thank you. Shaft seal operating conditions: Shaft seal; Process fluid; Shaft seal brand: TYPE John Crane 5620PR; Process fluid temperature: 40 ℃; Double Mech. Seal; Tank pressure: 9.5 kg/cm2; Seal ring material: SiC—CBRAON; Shaft seal chamber temperature: 43 ℃; O-ring materials: EPDM on the inner side, VITON on the outer side; Lubrication method: Plan 53
It’s probably a problem with the sealing method; mechanical seals are not as good as magnetic seals.
If the actual operating conditions are the same as those provided by the poster, this seal should not leak.
Change it to a shielded pump – zero leakage.
Reply to 5# yehuaqi007: Although the investment is large, it solves the problem at its root, so it is worth studying. . .
We still have an alkali pump. The corrugated seal selected costs over 3,600 per set; it can last more than a year, which is pretty good.
I don’t think EPDM should be used
Can the inner O-RING be made of KALREZ6375 or CHEMRAZ505? These two materials should be resistant to corrosion. Also, the price is only 3600 – it’s very cheap. What is the shaft diameter? I’ll buy one. Everything related to 375 costs over 10,000.
It’s due to the incorrect selection of the O-ring material; feel free to contact me if there are any issues