Metal parts including the seal barrel, cartridge sleeve, springs, set screws, etc. Choose a low friction face combination to reduce unwanted heat at the lapped faces. Carbon vs.the hard fac e silicone carbide is probably your best choice Select rubber parts that include O-rings, and gaskets. Keep the seal springs out of the fluid. This will make the springs less likely to clog up with solid materials.
Springs are subject to chloride stress corrosion problems.
Be sure any dynamic elastomer moves to a clean surface. Do not let the elastomer move into any potential solids that could restrict its' movement and open the seal faces. Choose designs that keep the sealing fluid at the outside diameter of the seal face. Centrifugal force will then work with you to throw solids away from the lapped seal faces. Avoid spring loaded elastomers or rubber parts Spring-loaded elastomers cannot flex or roll.