Flow-regulators

Air flow regulators are used in pneumatic circuits to control the air supply to, or exhaust from, pneumatic actuators, directly influencing valve opening and closing speed. Their use is primarily associated with quarter-turn rotary actuators, NAMUR-mounted valves, cylinders, and auxiliary automation circuits where controlled speed variation is required without changing supply pressure.

This category includes Hafner flow regulators with NAMUR interface for 3-way and 5-way valves. Types DRN 3 601 and DRN 3 611 are intended for 3-way NAMUR valves, with orifice 5, flow rate 650 l/min, operating pressure 0.5-10 bar, and NAMUR 1/4” interface. Type DRN 3 128 has orifice 8, flow rate 1500 l/min, operating pressure 0.5-10 bar, and NAMUR 1/2” interface. For 5-way NAMUR valves, types DRN 5 601 and DRN 5 611 are available, with orifice 5, flow rate 650 l/min, and operating pressure 0.5-10 bar.

Adjustment may be manual or screwdriver-operated, depending on model execution. Selection should consider required actuator speed, actuator chamber volume, instrument air pressure, single-acting or double-acting operation, exhaust configuration, and compatibility with the NAMUR mounting pattern of the valve or actuator. In practice, flow setting affects stroke time, dynamic response, and the balance between actuation speed and cushioning.

During installation, verify flow direction, air cleanliness, presence of moisture or oil carryover, proper seating on the NAMUR interface surface, and the effect of adjustment on total system response time. Excessive flow restriction can lead to delayed actuation, incomplete stroke, or unstable operation in valves with high breakaway torque. For maintenance planning, leakage at the interface, contamination of throttling passages, and repeatability of the adjustment setting should also be considered.