Pneumatically Actuated Valves - Block-form flow regulators | Hafner

Hafner Flow Regulators in Block Form

Hafner D / DR series are compressed air flow regulators with block-type bodies, designed for in-line installation in pneumatic circuits. Typical applications include cylinder speed control, flow restriction in pilot lines, and balancing actuation times in automation machinery. The range covers both bidirectional and unidirectional versions.

D and DR Series Versions

• D 501: G 1/8”, bidirectional regulation, up to 450 l/min, pressure range 0.5–10 bar.
• D 801: G 1/4”, bidirectional regulation, up to 1150 l/min, pressure range 0.5–10 bar.
• D 101: G 3/8”, bidirectional regulation, up to 1450 l/min, pressure range 0.5–10 bar.
• DR 501 / DR 801 / DR 101: unidirectional regulation with free flow in the reverse direction, for single-direction speed control.

According to Hafner technical data: aluminium body, suitable for compressed air, temperature range -10…+50 °C, flow rates specified at P1 = 6 bar, ΔP = 1 bar.

Bidirectional vs. Unidirectional Regulation

The D series throttles flow in both directions, suitable for general flow limitation in circuits.

The DR series regulates flow in one direction and allows return via a check function, used for controlling cylinder speed in one stroke without delay on the return.

Selection Criteria

Selection should consider:

• Required flow rate and cylinder actuation time
• Connection thread: G 1/8”, G 1/4”, or G 3/8”
• Regulation in one or both directions
• Available air pressure
• Installation location (near valve or actuator)
• Requirement for stable setting after commissioning

Maintenance

Inspect for contamination at the throttling point, setting stability, thread leakage, and air cleanliness. In circuits with variable pressure, verify final cylinder speed under actual operating conditions.