GRLO Throttle Valve

Festo GRLO Throttle Valve

Festo’s GRLO throttle valve is engineered to deliver adjustable, reliable control of compressed-air flow in automation systems, whether for cylinder speed regulation or system balancing. Built on a compact design platform, these valves allow both supply- and exhaust-side flow control (in the bidirectional versions) and support a wide range of pneumatic installations.

These valves are available in multiple configurations – including standard metal body, mini versions, and in-line installation styles – offering flexibility for diverse mounting and flow requirements.

⭐ Important: The GRLO throttle valve offers both-direction flow control, precise adjustment via a screw mechanism, and global compatibility thanks to its standardized port and thread options.

Design & Functionality

Throttle valves regulate piston or actuator speed by restricting flow of compressed air in one or both directions. In the GRLO series, a small adjustable annular gap inside the valve is turned via a slotted-head or knurled screw to set the desired flow rate. 

Festo offers various variants including:
• Standard double-ended flow control version (bidirectional)
• One-way (exhaust or supply) versions
• Mini versions for low-flow or tight-space applications
• In-line installation versions with push-in connectors or threaded ports

These valves are designed for high repeatability, low internal leakage, and long service life, even under varying loads or cycle rates. 

⭐ Important: With flow adjustability in both advance and retraction directions, the GRLO provides full control of motion speed and behaviour in pneumatic systems.

Total Crossed Beams

(Applied to the functional coverage of valve families)

Complete flow-control coverage is provided by multiple valve versions engineered for either uni- or bi-directional throttling. This enables full operational capability irrespective of installation orientation, cylinder type or stroke requirement.

Designed to maintain stable and consistent volumetric flow rates across a broad pressure range, helping ensure machine repeatability and smooth operation.

Beam Pitch Options

(Translated as: flow variants, actuation types, construction styles)

Wide variety of flow capacities, port/connection sizes, and body constructions offered in the GRLO family:

• Flow capacity from low-flow (mini versions) up to medium/high-flow standard versions 
• Connection types: threaded ports (M3, M5, G1/8, G1/4) plus push-in-connector options (QS-3, QS-4, QS-6) 
• Construction: metal bodies (standard) and polymer/mini bodies for lighter weight or tight-space use 
• Adjustment: slotted-head screw or knurled screw for fine flow tuning

⭐ Important: The broad selection of flow ranges, port sizes and construction styles ensures the valve can be tailored for everything from precision low-speed cylinder control to larger actuator speed regulation.

Intrinsic Synchronism

The internal spool and adjustable gap mechanism ensure consistent, synchronized control of flow with minimal variation or hysteresis. Optional mounting formats (inline, panel, manifold) improve stability when used in multi-valve assemblies or terminal installations.

Ensures repeatable flow behaviour, supporting high-precision motion control and accurate machine performance.

Operational Advantages

• Precise speed control for pneumatic actuators, both advance and retract
• Compact and robust design supports tight installations and harsh conditions
• Installation flexibility via multiple connection/interface options
• Low maintenance due to durable components and fine adjustment mechanism
• Standards-based connection- and porting layout enabling easy integration and replacement

Applications: Cylinder speed regulation, handling systems, packaging machines, actuator control, compressed-air distribution systems, automation plants.