Solenoid Valves - Double 3/2-way valves | Hafner

Hafner Double 3/2 Solenoid Valves

Hafner double 3/2 solenoid valves integrate two independent 3/2 functions within a single body/base. These are specified for pneumatic circuits requiring two separate air commands in a compact installation footprint, such as signal control, actuation of small single-acting cylinders, or combined supply and exhaust operations.

Available Configurations

The range includes MMD 231 / 232 / 233 304 models with a nominal orifice DN 3, flow rate 230 l/min, operating pressure 3…8 bar, and coil power consumption 0.6 W.

• MMD 231 304: double 3/2, NC & NC
• MMD 232 304: double 3/2, NC & NO
• MMD 233 304: double 3/2, NO & NO

NC / NO Selection Logic

Selection is based on the required default position without electrical supply:

• NC: output remains closed when de-energized.
• NO: output remains open when de-energized.
• NC & NO: suitable when two functions require opposite rest states.

Correct selection impacts circuit behavior during power loss, machine stop, or emergency shutdown.

Industrial Applications

Commonly used in:

• pneumatic panels with space constraints
• packaging and assembly machinery
• control of small single-acting cylinders
• blow-off and ejector control
• PLC auxiliary commands to pneumatic devices

Comparison with 5/2 Valves

A 5/2 valve typically controls a double-acting cylinder. The double 3/2 valve provides two independent 3/2 flows, enabling control of two separate functions or specialized pneumatic logic requiring isolated supply and exhaust paths.

Maintenance Considerations

Routine inspection should include air quality, leakage at ports, coil voltage, valve response, and base connection integrity. An air filter upstream of the pneumatic circuit is recommended for consistent operation.