L Series Compact Inline Directional Control Valves by Automatic Valve

Key Features and Engineering Design

L Series compact inline valves incorporate Automatic Valve's proven engineering principles in a space-efficient package. The solenoid pilot design uses full air line pressure to shift the valve spool, delivering fast response times with low electrical power consumption. Every solenoid is guaranteed against burnout, and weather-proof coils are hermetically sealed as integral, water-tight molded units designed to function reliably in rugged environments.

The bidirectional tapered Tee-Seal eliminates the sticking problems that plague conventional spool valves and has been validated to SAE specifications with rust and water injection every 864,000 cycles over a 20-million-cycle endurance test. Manual override capability allows operators to actuate the valve manually during electrical failure or for quick cycle testing. The external pilot supply is easily field-convertible, enabling vacuum service and other specialized applications.

Pressure controlled L Series valves provide an alternative actuation method for systems where electrical control is not required or not desired. These pneumatically piloted valves offer the same spool construction, seal technology, and mounting versatility as their solenoid counterparts, making them ideal for remote or intrinsically simple control architectures.

Specifications and Operating Conditions

L Series compact inline valves are engineered for broad environmental and operational versatility. Standard temperature models operate from -20 degrees F to 123 degrees F (-29 degrees C to 50 degrees C), high temperature models handle 0 degrees F to 180 degrees F (-18 degrees C to 82 degrees C), and low temperature models extend down to -40 degrees F (-40 degrees C to 50 degrees C). For temperatures below 40 degrees F, the air supply must be free of water vapor to prevent ice formation.

Operating pressure and flow capacity vary by series. The smaller L05 and L07 series handle lower flow ranges suitable for instrument and pilot applications, while the L20 and L21 series serve mid-range requirements. The L45 and L65 series deliver higher flow capacity up to Cv 9.5 for larger actuator control. All series accept filtered air as the flow media.

Solenoid options span DC voltages of 12V and 24V with power consumption options including standard and low-power variants, and AC options at 120V and 240V at 60 Hz. Electrical connections include DIN EN 175301-803 Form A and Form B connectors, M12 connectors, and molded coils with flying leads. Construction materials include aluminum valve bodies, Polyamide 66 solenoid housings, and Buna-N or Fluoroelastomer seal options for broad media compatibility.

Valve Functions and Series Selection

The L Series covers three primary valve functions across its six series to address virtually any directional control requirement. The 3/2 normally closed valve provides three-way, two-position control ideal for single-acting actuators, spring-return cylinders, and on/off pilot applications. Available in the L20, L21, L45, and L65 series with port sizes from 1/4 inch to 3/4 inch, these valves offer both solenoid pilot and pressure controlled actuation.

The 5/2 valve function delivers five-way, two-position directional control for double-acting actuators and cylinders. This configuration is available across the full range from L05 through L65, with port sizes from 1/8 inch to 1 inch and single or double solenoid actuation options. The 5/2 function represents the broadest selection within the L Series, with flow capacity reaching Cv 9.5 in the larger series.

The 5/3 valve function provides five-way, three-position control with closed center, open center, or power center configurations. These double solenoid valves maintain a stable center position when de-energized, offering fail-safe positioning and mid-stroke stop capability. Available in L07 through L65 series, the 5/3 function supports applications requiring precise position control and emergency stop compliance.

Manifold and Mounting Options

L Series compact inline valves support three primary mounting configurations: inline (individual valve), manifold, and bottom mount. Inline mounting provides the simplest installation for standalone valve applications, with threaded port connections for direct piping. Bottom mount configurations enable panel or subplate mounting for organized valve stations.

Manifold mounting is available for both 3/2 valves (L21 series, top mount) and 5/2 and 5/3 valves across multiple series. Manifold bases consolidate multiple valves into a single assembly, reducing piping complexity, minimizing leak points, and simplifying installation. Manifold accessories include end stations, blanking plates, and connection adapters that allow flexible system configuration.

The compact inline design of the L Series makes it particularly well-suited for applications with limited installation space. The lightweight construction reduces mounting stress and supports applications where vibration resistance is important. Downloadable CAD models are available for all L Series valves and manifold configurations, enabling seamless integration into machine design and plant engineering workflows.

Accessories and Electrical Connectors

Automatic Valve provides a comprehensive range of accessories for L Series compact inline valves. Electrical connectors are available in DIN EN 175301-803 Form A and Form B configurations, both with and without integral indicator lights. Prewired electrical connectors with 6-foot cables simplify installation by providing ready-to-connect wiring solutions. Lighted connector options include 6-48V AC/DC and 100-240V AC / 48-120V DC versions.

High-flow exhaust silencers are available to reduce noise from valve exhaust ports while maintaining adequate flow capacity. Silencer options include zinc-plated steel and stainless steel construction with port sizes matched to the valve series. Exhaust restrictor silencers provide additional flow control capability at the exhaust port. All silencers are designed with flow capacities at least as great as the exhaust capacities of the valves to prevent backpressure-related performance issues.

Additional accessories include manifold end stations, blanking plates, and adapter plates that support flexible system design. Automatic Valve's engineering team is available to assist with custom configurations and special application requirements through their Ferndale, Michigan headquarters and the ROSS Global Family's worldwide network of sales and support offices.

Frequently Asked Questions About L Series Compact Inline Valves

What port sizes are available for L Series valves?

L Series compact inline valves are available with inlet port sizes ranging from 1/8 inch to 1 inch, depending on the series. The L05 and L07 series start at 1/8 inch, the L20 and L21 series cover 1/4 to 3/8 inch, and the L45 and L65 series handle 1/2 inch to 1 inch ports. This range allows engineers to select the optimal valve size for their specific flow and pressure requirements.

What is the maximum flow capacity of L Series valves?

The maximum flow capacity of L Series compact inline valves is Cv 9.5 (9,300 Nl/min), achieved in the larger L45 and L65 series for 5/2 valve configurations. Smaller series offer proportionally lower flow capacities suited to pilot, instrument, and light-duty actuator applications.

Are L Series valves available in both solenoid and pressure controlled versions?

Yes, the L Series is available in both solenoid pilot controlled and pressure controlled configurations. Solenoid pilot versions use electrical actuation with weather-proof coils, while pressure controlled versions use pneumatic pilot signals. Both types share the same spool construction, Tee-Seal technology, and mounting interfaces.

What SIL rating do L Series valves achieve?

L Series compact inline valves are certified by SGS-TUV Saar per IEC 61508. They achieve Safety Integrity Level 2 (SIL 2) in singular application with hardware fault tolerance of 0, and SIL 3 with Performance Level e in redundant application with hardware fault tolerance of 1 or greater.

Can L Series valves be manifold mounted?

Yes, manifold mounting is available for L Series valves. The L21 series supports top-mount manifolds for 3/2 valves, and multiple series support manifold bases for 5/2 and 5/3 valves. Manifold accessories including end stations, blanking plates, and connection adapters enable flexible multi-valve system configurations.