do sump pumps have built in check valves

Zoeller 007921, Model 131 (M98) Replacement Cast Iron Effluent Sump Pump, .5 HP, 115 Volts, 1 Phase, 9.4 Amps, 1-1/2 NPT Discharge, 72 GPM Max, 23 ft Max Head, 9 ft Cord, Automatic

Zoeller 131 (M98) Replacement Effluent Pump

This submersible pump is designed for use in residential or light commercial dewatering applications and can be used to transfer groundwater or effluent. This replacement pump can be used in M98 sink drain pump system (131-0001). This durable cast iron pump includes a powder coated epoxy finish to prevent corrosion and is designed to provide great heat dissipation from the motor, ensuring a long service life. As with every Zoeller pump, each one is 100% pressure-tested, submerged and run to ensure quality and reliability for years of trouble-free performance.

Features

Replacement pump for 131-0001 sink drain pump system, Corrosion resistant powder coated epoxy finish, Durable cast iron switch case, motor, pump housing and base, Stainless steel screws, guard, handle, arm and seal assembly, Float operated submersible (NEMA 6) 2-pole mechanical switch, Stainless steel float guard and switch arm, and a solid, buoyant polypropylene float, Watertight neoprene ring between motor and pump housing, Motor - Permanent split capacitor, 60 Hz, 1725 RPM, oil-filled, hermetically sealed, automatic reset thermal overload protection, Engineered plastic, non-clogging vortex impeller, Bearings - Upper & lower oil fed cast iron, Carbon and ceramic shaft seal, No screens to clog, Passes ½" spherical solids, 1½" NPT discharge, On point - 9½", Off point - 3", Maximum temperature for effluent or dewatering 130° F, 9 ft UL listed standard cord, Entire unit pressure tested after assembly

Note: Image is illustrative and may not reflect details of actual product.