Line of internal gear pumps is designed for refrigeration ammonia recirculation applications. The cast iron, positive-displacement pumps offer safe, reliable operation for longer life under high pressure conditions. Safety is achieved by a double-mechanical dynamic shaft seal located between bearings for minimum possible shaft run-out, with a pressurized barrier fluid system, and O-ring type static seals where components are joined. Reliability is provided by slow speed operation and low differential pressures. Series 4924A includes a return-to-tank (RTT) pressure-relief valve (PRV) as a standard feature for routing ammonia from any overpressure situation back to the tank. A flush line with valve carries ammonia from behind the rotor to the reservoir, pressurizing the barrier oil to the same pressure seen by the seal inside the pump. The oil level can be maintained using a sight glass with frost shield for visual inspection in cold installations.
Viking Pump Inc.