National Stock Number
4320-00-201-8540
National Stock Number (NSN) 4320-00-201-8540, or NIIN 002018540, (ring,wearing) was assigned March 28, 1973 in the Federal Logistics Information System (FLIS). This NIIN is Available for Manual Assignment. This NSN does not replace any other NSNs.
There are 4 manufacturer part numbers associated with this NSN. 2 of those part number(s) are considered obsolete. The manufacturer part numbers were originally supplied by 3 suppliers. Today, 2 suppliers are listed as Active suppliers for this NSN. Of the active suppliers, only one supplier is deemed design controlled or valid supply parts. ISO Group has several sources of supply for this NSN.
This part number has not been procured by the US Government in over 5 years.
This NSN is somewhat common among different platforms, belonging to 5 different weapons systems.
Based on a planned procurement review by the Primary Inventory Control Activity (PICA) on Jan 01, 2013, this NSN's acquisition method was noted as: Suitable for Competitive Acquisition. (Potential sources shall include dealers/distributors.) The data or the rights to use the data needed to purchase this part from additional sources are not owned by the Government and it has been determined that it is uneconomical to purchase them. Valid AMCs: 1, 2, 3, 4 and 5.
This NSN is assigned to Item Name Code (INC) 22534. [A CYLINDRICAL ITEM WITH OR WITHOUT FLANGE(S), DESIGNED TO BE INSERTED IN A PUMP CASING OR SECURED TO THE IMPELLER OF A CENTRIFUGAL PUMP. IT IS USED FOR THE PURPOSE OF PROVIDING A CLOSE RUNNING CLEARANCE BETWEEN THE IMPELLER AND CASING IN ORDER TO PREVENT OR OVERCOME LEAKAGE DUE TO EROSION. IT MAY ALSO BE USED AS A DIFFUSER RING IN THE SUCTION AND DISCHARGE THROATS OF VALVES.]. This item does not have a nuclear hardened feature or any other critical feature such as tolerance, fit restriction or application. There is no data in the HMIRS and the NSN is in an FSC not generally suspected of containing hazardous materials. NSN 4320002018540 contains an unknown precious metal.
This NSN is associated to Schedule B 8413919520: parts, nesoi, of pumps for liquids. The Schedule B End Use is listed as industrial engines. NAICS classification category 333911: pump and pumping equipment manufacturing.
This information was last updated on Aug 01, 2025.