Manually-operated valves with slide valve or level

Order Manual Directional Control Valves with Toggle Lever or Slide Valve

Manually operated directional control valves control pneumatic flows directly at the machine. In applications such as robotics, textile industry, printing presses, and plastics processing, they primarily serve for targeted venting of the outlet line, for supplying or interrupting the inlet air, and as a simple actuator alternative to electro-pneumatic valves. In this category, you will find Legris valves in 3/2 and 2/2 configurations, available as 3/2 inlet directional control valves, 3/2 exhaust directional control valves, as well as with toggle lever or manual slide valve. The selection is based on operating pressure, flow rate (Cv or Kv), connection type, and sealing material.

Design Principles and Types

Manual directional control valves are constructed as toggle lever or slide valves. Toggle lever valves use a lever with a defined detent point, which can be returned to the neutral position by spring pressure or can be locked in the actuated position. Manual slide valves have an axially displaceable slide or cone that mechanically opens or closes the channels. Both designs are available in inline or angle housing. Inline housings allow direct line entry along the flow axis, while angle housings save installation space and facilitate installation in confined machine setups.

Materials, Surfaces, and Corrosion Protection

Housing materials range from technical thermoplastics (PA, POM) to die-cast aluminum, brass, or stainless steel for higher stress or more aggressive media. Thermoplastic housings reduce weight and cost, are chemically resistant to oil- and water-based media, and are suitable for standard applications. Aluminum housings offer higher mechanical strength and better heat dissipation. Brass and stainless steel are used in corrosive environments or where increased hygiene requirements apply. Surfaces can also be anodized, nickel-plated, or passivated to minimize corrosion and reduce friction in the actuation mechanism.

Connections, Standards, and Seals

Typical connection types include threaded connections according to ISO/EN (G BSPP), NPT for international applications, as well as push-in fittings or quick-connect couplings for hoses. For modular valve islands or installation in pneumatic distributors, standard drilling patterns according to ISO 15407 or ISO 5599-1 often exist. Seals are critical components: NBR (nitrile) covers standard applications up to 80–90 °C and is oil-resistant; FKM (Viton) is suitable for higher temperatures and aggressive media; EPDM is used for steam and water applications. For particle-free or food-grade applications, PTFE seals are used. When ordering, pay attention to the appropriate seal design for the ambient temperature and medium.

Performance and Specification

Key parameters include switching function (2/2, 3/2), flow cross-section (Kv or Cv), maximum switching frequency, permissible operating pressure, and leakage rate. A 2/2-way valve offers a simple open/close function, suitable for shut-off and safety tasks. A 3/2-way valve additionally allows for venting (exhaust) or switching between two states (inlet/exhaust). For fast piston cycles in robotics, a high switching frequency and a large Cv value are crucial; in printing presses with finely dosed venting, low leakage rates and finer seals are more relevant.

Installation Position, Mounting, and Ergonomic Operation

The installation position influences seal wear and actuation effort. Toggle lever valves are more tolerant of dirt and provide clear tactile feedback, while manual slide valves allow for slimmer operating profiles and integrate better into linear slide guides. Mounting flanges, fastening lugs, or threaded studs facilitate direct attachment to machine frames. For operators with frequent actuation, an ergonomic lever design with a large actuation travel and lockable detent is recommended.

Safety Aspects and Maintenance Requirements

Manually operated valves do not serve as safety components in the sense of PL or SIL, unless they are explicitly designed and certified for this purpose. Maintenance intervals depend on actuation frequency, ambient dirt, and medium. Replaceable seal kits and easily accessible repair elements reduce downtime. When used in dusty environments, an additional protective cap for the actuator is recommended. Spare parts should be compatible with the original series; documented service instructions and material specifications facilitate quick repairs.

Practical Examples of Structured Application

Example 1 — Robotics: In a pick-and-place cell, a 3/2 inlet directional control valve with toggle lever controls vacuum generation via a suction nozzle. During setup times, the operator manually switches off the inlet air via the lever to allow workpiece changes without vacuum. Due to frequent actuation, a lever with spring return was chosen, combined with NBR seals for oil resistance in the gripper area. Example 2 — Textile Industry: In the thread feeding of a weaving loom, a 2/2 manual slide valve prevents "snatching" by targeted venting of the nozzle line during maintenance work. The valve is designed in stainless steel with EPDM seals to ensure long-term resistance to cleaning agents and moisture. Example 3 — Plastics Processing / Injection Molding: For nozzle cleaning, an angle 3/2 exhaust directional control valve is installed, which quickly and completely vents the drain line. The design with a brass housing and PTFE seals minimizes abrasion and ensures chemical resistance to cleaning fluids. A large flow passage (high Kv value) accelerates the venting of large volumes. Further practical examples and technical background can be found under Application Examples and detailed technical pages under Technology.

Selection Criteria for Purchase

Choose the valve according to functionality (2/2 vs. 3/2), actuation type (toggle lever vs. manual slide valve), connection standard, material combinations, and seal design. Check operating pressure and temperature range, leakage rates, and compatibility with existing quick-connect fittings. For series machines, models with modular replacement seals and documented interchangeability are recommended to minimize maintenance times.

• Quick check before ordering: Switching function, connection size/thread, material/seal, Kv value, installation dimensions, and mounting options

Procurement and Delivery Information

Order valves with clear specifications of connection thread, nominal flow, and sealing material. Stocked variants are often plastic or aluminum housings with NBR seals; special designs in stainless steel or with FKM seals require longer delivery times. When retrofitting existing systems, check compatible connection and drilling pattern standards; otherwise, modular installation via adapters or quick couplings is recommended.

Frequently Asked Questions (FAQ)

1. Which seal is suitable for my application?

For oil and hydraulic proximity, NBR; for high temperatures and aggressive chemicals, FKM (Viton); for water and steam applications, EPDM; PTFE for high demands on chemical resistance and cleanroom environments. Choose the seal according to the medium and operating temperature.

2. When do I need a 3/2-way valve instead of a 2/2-way valve?

A 3/2-way valve is necessary when, in addition to allowing flow through a line, targeted venting or switching between two states is also required. For pure shut-off tasks, a 2/2-way valve is sufficient.

3. How does the actuation type affect maintenance and service life?

Toggle levers offer robust, tactile operation and are more resistant to contamination; manual slide valves have more compact designs but can stress seals faster with improper operation. Maintenance intervals primarily depend on switching frequency and environmental conditions; replaceable seals reduce downtime.