A fluid handling system for a particle processing instrument includes a pump, a pulse attenuator, a pressure transducer, and a pump controller. The pump may be configured to supply a pulsed flow of fluid having a first pulse characteristic to the pulse attenuator. The pulse attenuator may have a single, undivided, volume, fluid inlets, fluid outlets, and a pressure sensor port. The pulse attenuator may supply an outlet flow of fluid having a second pulse characteristic different from the first pulse characteristic. The pressure transducer may be in fluid communication with the pressure sensor port and in control communication with the pump controller. The pump controller may be in control communication with the pump to maintain a substantially constant nominal pressure within the pulse attenuator by controlling the pump motor.