The NSSA option is recommended when a pump must be operated on a continuous duty basis OR when the differential pressure requirement is over 125 PSI on a continual duty basis. The NSSA option can be specified for normal pump duty as well. In these applications, a 3-fold increase in pump life would be expected. Included in the NSSA option is a gear set fabricated from aircraft quality steel, and idler gear shafts made from Tungsten Carbide. The NSSA option is automatically included in the MCAT series 3-inch flange mount truck pump as standard equipment. Not available for D-series or E-series pumps. The NS option is identical to the NSSA option BUT does not include the upgraded Tungsten Carbide idler gear shafts. The NS option is recommended for systems where higher than normal differential pressures may be encountered on an intermittent basis. The SUPERSEAL option is provided as standard equipment on all D-series, E-series and MCAT-series pumps. The SUPERSEAL utilizes a thermoplastic seal ring that continually seats itself EVEN in conditions of high vapor concentrations. Because of the unique shaft seal assembly design, the seal ring actually rotates at one-half shaft speed, greatly increasing productive seal life. All Smith mechanical shaft seal assemblies are dynamically tested in an external testing apparatus at the factory and are shipped in the as tested state. All seal components are preassembled onto the pump shaft for ease of replacement in the pump should it ever be necessary. Specify the L option for increased pump capacity. Available for models MC-1044, MC-1044H, MC-2, MC-3, MC-4 and MC-5, the L-option will boost capacity by 25% at the same rated motor speed.