Material selection for titanium pump seals
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Generally, titanium pumps are preferred for transporting media with high free chlorine levels and concentrated sulfuric acid. It is also very important to choose the appropriate material for the pump’s mechanical seal; the proper selection of the mechanical seal material determines its reliability. Very high requirements are placed on mechanical properties and chemical stability. The quality of mechanical seals depends to a large extent on the properties of the materials used. When selecting and using such seals, it is important to note that the commonly used materials include small cylindrical springs; these springs are made of nickel or nickel alloys. Hastelloy C (HAS-C) can be used as an alternative material, but stainless steel cannot be used. In sealed friction pairs, it is common to use silicon carbide (SiC) for both the moving and stationary rings; silicon nitride (Si3N4) can also be used. Materials of the same hardness should be selected for these rings. The stationary ring is of a monolithic design, while the moving ring is embedded-type – that is, the SiC ring is embedded in Ti-0.15Pd alloy or in TA2 or TA3. TA2 and TA3 are often used as materials for the mechanical seal frame. HAS-C alloy is used for positioning and fixing screws, and fluororubber is used for the sealing rings.
Generally, titanium is not suitable for use with concentrated sulfuric acid; however, it can be used with sulfuric acid of a certain concentration if it contains an appropriate amount of chloride ions. Without oxidizing components such as chloride ions, it can only be used at 10% and below 60 degrees. For your reference.
:The spring consists of multiple small cylindrical springs. According to available information, springs are not as good as bellows-type mechanical seals – is that correct?
Yes, but it’s better to use Krane or imported bellows. Domestic technology is too poor
I came across another source stating that for long-term operation, a secondary impeller seal is suitable, while for machinery that is started and stopped frequently, a mechanical seal is better. May I ask what type of seal the secondary impeller seal belongs to? Is it a dynamic seal? What’s its price?