- Automation & ControlView all 1,841 products
- AC Drives
- PLC & I/O Cards
- Industrial Communications
- Vibration Monitoring
- Automation Accessories
- Controllers & Data Acquisition
- Isolator & Barrier
- CCTV & Security
- Safety Switches & Guard Locking
- Encoders
- HMI Displays
- Industrial Computers
- Servo Drives
- Motor Soft Starters
- Pneumatic Cylinders
- Machine Vision
- Automation Software
- Robotics
Brand: Flowserve
Flowserve Valtek VL Spring Cylinder Linear Actuator
Description
Valtek VL spring cylinder linear actuator: what the VL series is
The VL is the standard pneumatic spring cylinder linear actuator on Flowserve Valtek control valves. Instead of a diaphragm, it uses a piston in a cylinder. The positioner sends supply air to both sides of the piston, which gives stiff, precise movement and a fast response, while a spring inside the cylinder drives the valve to its fail position if air is lost. Seven Star LLC supplies VL actuators in Oman and the GCC as an independent supplier in Muscat. The VL is a family sized by piston area in square inches, so the correct size and spring are chosen from the valve data.
The maker states that VL actuators have been in service for more than 30 years, and the cylinder is described as compact and light. It can be fitted with the Logix, XL and Beta positioners from the same maker.
VL technical specifications
| Parameter | Specification |
|---|---|
| Manufacturer / part number | Flowserve Valtek / VL spring cylinder linear actuator (variants VL, VL-C, VL-UHC, VL-ES) |
| Actuator type | Pneumatic linear spring cylinder actuator, double-acting piston with fail-safe spring |
| Operating pressure | Up to 150 psi (10.3 bar) without a pressure regulator |
| Minimum operating pressure | As low as 30 psi (2.1 bar); limited on some sizes by valve size |
| Standard sizes | 25, 50 and 100; larger sizes through 600 for special applications |
| Stroke | Up to 24 in; size 25 has a 1.5 in (38 mm) stroke |
| Cylinder and piston (VL) | Painted anodized aluminum cylinder, anodized aluminum piston |
| Yoke | Phosphated and painted ductile iron |
| Actuator stem | 416 stainless steel |
| Seals and bushings | Buna-N O-rings; bronze Oilite bushings |
| Spring | Alloy steel; field reversible failure mode |
| Accessories | Positioners, handwheels, limit switches, solenoids, flow booster, air filters, position transmitter |
How the VL cylinder actuator works
The VL is a double-acting cylinder with a return spring. The positioner modulates air to the top and bottom of the piston, and the small air volume under the piston gives the actuator a stiff, spring-like response. That stiffness helps the valve resist the flow forces that otherwise push the plug around, so a high pressure drop can be handled without plug slamming. The spring does not set the control position; it provides the failure action, driving the valve to the fail position on air loss. The maker states that a spring bench set is not needed, and the failure mode is reversed in the field without extra parts.
VL variants: VL, VL-C, VL-UHC and VL-ES
| Variant | Construction | Intended use |
|---|---|---|
| VL | Aluminum cylinder and piston, ductile iron yoke, Buna-N O-rings | Standard actuator for Valtek control valves; two parts to remove for internal access |
| VL-C | Carbon steel cylinder and piston replace aluminum; deep-drawn cylinder on sizes 25 and 50, tie-rod construction on size 100 and larger | Where aluminum is not acceptable |
| VL-UHC | As VL with quad seals, plug stem jam nut, thrust bearing and special springs | Up to 2 million full-stroke cycles with periodic soft-goods replacement |
| VL-ES | Carbon steel cylinder, external spring cans | Longer strokes or unusually high spring thrust |
VL-C cylinders are offered in sizes 25, 50, 100, 150, 200, 300 and 400. Check which variant is installed before ordering a spare, because internal parts such as pistons and seals differ between variants.
VL stroking times, stiffness and air supply
The maker publishes typical maximum-stroke times at 60 psi (4.1 bar) actuation pressure for two tubing sizes. These are stroking time only and exclude positioner response.
| Actuator size | Time, 0.25 in tubing | Time, 0.375 in tubing | Stroke |
|---|---|---|---|
| 25 | 1.2 s | 1.0 s | 1.5 in (38 mm) |
| 50 | 3.8 s | 3.0 s | 3 in (76 mm) |
| 100 | 11.5 s | 9.0 s | 4 in (102 mm) |
| 200 | not listed | 15.4 s | 4 in (102 mm) |
| 300 | not listed | 24.1 s | 4 in (102 mm) |
For a size 25 actuator with 150 psi supply and 1.5 in stroke, stiffness is 3,441 lb/in (603 N/mm) at 100% stroke and rises to 68,816 lb/in (12,052 N/mm) at 5% stroke, which shows how tightly the actuator holds position near the seat.
Where the VL fits and related Valtek parts
The VL is the actuator side of a Valtek control valve; the valve body, trim and positioner complete the loop. Common positioners are the Logix 3000 and Logix 500 digital series with HART, the Logix 3000 with Foundation Fieldbus, and the XL and Beta analog positioners. ValveSight software supports diagnostics. A PosPac transmitter can add a 4-20 mA position feedback signal. Compare the VL with Automax rack-and-pinion actuators, which suit quarter-turn valves rather than linear control valves.
Selection and ordering checklist for the VL
- Valve model, stem size and stroke length.
- Required thrust for shutoff and for maximum pressure drop, to select the actuator size and spring.
- Fail-safe action: fail open or fail closed (reversible in the field).
- Available instrument air pressure at the actuator, between 30 and 150 psi.
- Variant needed: VL, VL-C (no aluminum), VL-UHC (high cycles), VL-ES (long stroke or high spring thrust).
- Positioner and accessories: handwheel, limit switches, solenoid, flow booster, volume tank or lockup.
- Stroking time required, which affects tubing size and any booster.
Installation, commissioning and maintenance of the VL
Connect clean, dry instrument air and tube the positioner to both ports of the cylinder. Stroke the valve across its range, check the stem clamp and stroke plate, and calibrate the positioner. Maintenance is simple because the maker states that only two or three parts need to be removed to reach all internal parts, and there is no diaphragm to rupture. Wear items are O-rings, quad seals on the UHC and ES variants, and bushings. Keep seal kits for critical valves, and check the stem O-ring and bellows condition at planned outages.
Typical VL applications in Oman and the GCC
Valtek control valves with VL actuators serve throttling and on-off duty in oil and gas processing, refining, petrochemical and power plants. For these duties the high thrust and stiffness help in high-pressure-drop letdown, compressor recycle and steam service. High ambient temperatures and dust favor a cylinder that has no diaphragm, and the carbon steel VL-C is the choice where site rules prohibit aluminum parts. For frequent cycling duty, consider the VL-UHC.
Information to send with an RFQ for the VL
- Existing actuator nameplate: size, stroke and spring data.
- Valve model, size and trim data, and shutoff differential pressure.
- Fail action and supply air pressure.
- Positioner model and any accessories required.
- Ambient range and material restrictions such as no aluminum.
- Quantity and delivery location in Oman or the GCC.
Documents and quotation
The maker’s Valtek spring cylinder linear actuator brochure is attached on this page, with materials of construction and the variant descriptions. Use it to confirm which variant you have.
Send the VL size, stroke and air supply details to Seven Star LLC and we will prepare a quotation for Oman and the GCC.
Datasheets & Documents
- Catalog Flowserve Valtek Spring Cylinder Linear Actuator Brochure Download
Reviews (0)
About brand
Flowserve is the American flow control company for pumps, valves, mechanical seals and valve automation, known through brands such as Durco, Worthington, Byron Jackson, Valtek, Limitorque, Worcester, Logix and Argus. It was formed on 22 July 1997 by the merger of equals of Durco International and BW/IP, whose heritage reaches back to Simpson & Thompson (1790) and Byron Jackson (1872). Flowserve Corporation is headquartered in Irving, Texas, and listed on the New York Stock Exchange.
Seven Star LLC sources and supplies Flowserve pumps, seals, control valves, ball valves, actuators and positioners for process plants in Oman, working from the nameplate data and the manufacturer's documentation.
Flowserve company profile
| Formed | 22 July 1997, merger of Durco International and BW/IP |
|---|---|
| Heritage companies | Simpson & Thompson, later Worthington Simpson (1790); Byron Jackson (1872); Duriron foundry, later Durco (1912) |
| Headquarters | Irving, Texas, USA |
| Ownership | Flowserve Corporation, public company (NYSE: FLS) |
| Product families | API and ANSI process pumps, Durco and Worcester ball and plug valves, Durco TX3 triple-offset and Valtek butterfly and globe control valves, Limitorque electric actuators, Logix positioners, mechanical seals |
Milestones
- 1790: Thomas Simpson founds Simpson & Thompson, a predecessor of Worthington Simpson pumps.
- 1872: Byron Jackson is founded, a root of BW/IP.
- 1912: The Duriron foundry, later Durco, is launched.
- 1997: Durco International and BW/IP merge on 22 July to form Flowserve, listed on the NYSE as FLS.
Flowserve product families listed here
Flowserve pumps on this page are the Durco Mark 3 ANSI process pump and the ECPJ vertical sump pump built to API 610 type VS4. Sealing products are the ISC2 cartridge mechanical seal to API 682 and DuraClear barrier fluid for dual seal systems. Flowserve valves include the Valtek Mark One globe control valve, Argus floating and trunnion-mounted ball valves (EK71, FK79, FK76M) and Durco Microfinish ball valves. Automation is covered by Limitorque MX and L120 multi-turn electric actuators, the Rotadisk RD and RDF pneumatic actuator and the Logix 3800 digital positioner.
Where Flowserve equipment is used
Mark 3 pumps handle acids, caustic, solvents and utilities in chemical and petrochemical units. VS4 sump pumps drain pits and collection tanks. Valtek control valves and Argus ball valves are found in refining, gas processing, power and desalination, and Limitorque actuators operate gate and globe valves on pipelines, tank farms and water networks across the GCC.
Flowserve products we list
Ordering Flowserve parts: what we need
The serial number on the nameplate is the key to Flowserve records for a pump, valve or actuator. Please add the following by product type:
- Pumps: size and model, impeller diameter, materials, seal arrangement, and the part name and item number from the sectional drawing
- Mechanical seals: seal type and size, drawing or part number, materials code, pumped fluid and flush plan
- Valves: size, pressure class, body and trim materials, end connections, and the actuator and positioner model
- Limitorque actuators: unit size, order and serial number, supply voltage, wiring diagram number
Facts checked against Flowserve's SEC filings and published company histories, October 2026.
Browse Flowserve products by category: Control Valves, Pumps, Valve Actuator, Valve Positioner.
FAQ
Questions about the Flowserve Valtek VL Spring Cylinder Linear Actuator
Answers from our engineering team on installation, compatibility and integration.
01What supply pressure does the VL actuator need?
It handles up to 150 psi (10.3 bar) without a pressure regulator and can run on as little as 30 psi (2.1 bar). Some sizes are limited by valve size.
02What is the difference between VL, VL-C, VL-UHC and VL-ES?
VL-C swaps aluminum parts for carbon steel and VL-UHC adds quad seals and special springs for high cycle life. VL-ES uses external spring cans for long strokes or high spring thrust.
03How long is the stroke of a VL actuator?
Stroke goes up to 24 in. The size 25 unit has a 1.5 in (38 mm) stroke, and sizes 100, 200 and 300 are listed with a 4 in (102 mm) stroke in the stroking time table.
04Is the failure action of the VL adjustable?
Yes. The maker states that the failure mode is reversed in the field without extra parts. The spring provides the fail-safe action on loss of air.
05Which positioners work with the VL?
Logix 3000 and Logix 500 digital positioners, plus XL and Beta analog positioners, are listed by the maker. HART and Foundation Fieldbus versions exist.
Reviews
There are no reviews yet.