Masoneilan 5A Series Double-Acting Cylinder Actuator for Camflex II
Overview
The Masoneilan 5A is a double-acting cylinder actuator from Baker Hughes for Camflex II rotary valves. The instruction manual describes it as offered for globe rotary valves, with high capacity and excellent seat leakage performance in both directions, and notes that quick removal and replacement of valve components during maintenance saves valuable plant downtime. Double-acting air cylinders can be mounted on Camflex valves of 6 in. and larger, and they are usually used instead of the standard spring-diaphragm actuator when the valve pressure drop is high or the available air pressure is insufficient.
Seven Star LLC is the trusted supplier for Masoneilan in the Sultanate of Oman and supplies the Masoneilan 5A with Camflex II valves and as a conversion or replacement actuator for existing installations. This page is based on the Baker Hughes instruction manual rather than a numerical datasheet, so we confirm cylinder, lever and yoke details from your valve serial number before quoting.
Operating Principle of the Masoneilan 5A
The Masoneilan 5A actuator piston operates only by compressed pneumatic air and no spring is used. One side of the piston is loaded with air at a constant pressure through the positioner, while the output pressure of the operating instrument is exhausted through accessories, so the piston is driven positively in both directions. The piston stem is joined by a rod end bearing and clevis to a lever on the Camflex shaft, converting the linear stroke of the cylinder into rotation of the eccentric plug. The manual states that the actuator always closes the valve when the actuator stem is retracted into the cylinder.
If a safer actuation system is required when the air source is lost, the valve is fitted with an air volume tank and a transfer valve that operates to give the desired action. The manual notes that the direction of operation can be changed, either valve closed when air pressure increases or valve open when it increases, by connecting the air tubing to the other side of the cylinder, and it adds that verification of the Camflex valve shaft mechanical stress is mandatory according to the shaft material and service temperature.
Engineering Design of the Masoneilan 5A
The Masoneilan 5A cylinder always mounts on the left side of the yoke and is fixed with four cap screws and lock washers. Within that rule, it can be installed vertically or horizontally relative to the pipe according to surrounding obstacles, but the manual states that mounting positions are limited to two. A matching mark on the yoke and lever with the valve fully closed makes it easy to reassemble in the same position, and a travel indicator dot shows plug position through the front cover.
The manual’s parts list runs up to reference 107, including the piston cylinder, piston cylinder stem, rod end bearing, inner and outer O-rings, stop ring, limit stop, handwheel shaft and plate, handwheel lock, Lo-dB plate and adaptor. Handwheels can be installed on both sides of the yoke, with the larger wheel opposite the actuator, and can be removed by taking off the retaining ring. A handwheel may also be locked in place as a valve limit stop.
Key Features
These are the points that explain when the Masoneilan 5A is chosen for a Camflex II:
- The Masoneilan 5A double-acting piston copes with high pressure drop and low air supply pressure on larger Camflex valves.
- With no springs, the Masoneilan 5A gives positive actuation in both directions and good seat leakage performance.
- A volume tank and transfer valve provide a defined air-failure action when required.
- Operation can be changed between air-to-close and air-to-open by reconnecting the air tubing.
- On this actuator, handwheels on either side of the yoke can double as an adjustable valve limit stop.
- Matching marks on yoke and lever speed up reassembly and mounting-position changes.
- Quick removal and replacement of valve components reduces plant downtime.
- The manual defines preventive maintenance of O-rings, piston rod, piston and cylinder bore surfaces.
Industrial Applications
The Masoneilan 5A suits larger Camflex II valves in services where a spring-diaphragm actuator would be too large or too weak, for example high differential pressure on liquid or gas lines in refineries, gas processing and power plants. In Oman such cases occur in the production and processing facilities near Sohar and Duqm, and in utilities where plant air is limited and a cylinder with a volume tank is the practical answer.
In Oman and the GCC, Seven Star LLC supplies the Masoneilan 5A with the Masoneilan 35002 Camflex rotary control valve and with variants such as the high capacity and low-noise Camflex II models. Our engineers help decide whether the Masoneilan 5A cylinder actuator or a larger diaphragm actuator is the better fit, and can supply seal kits and O-rings for the cylinder.
Related published Masoneilan pages: Masoneilan SVI3 digital valve positioner and Masoneilan Type 51/52/53 piston actuators.
Technical Specifications
Preventive maintenance of the Masoneilan 5A centers on the cylinder: check the shaft for damage such as O-ring wear, look for burrs and surface roughness in the O-ring groove, check the piston rod and piston for sliding-part damage, and inspect the cylinder bore for scoring. Before any work the valve must be isolated to release process pressure and the supply and signal air shut off. Adjustment of the actuator stem and lever is done with the lever and plug fully closed and the stem retracted, because tight shutoff and full stroke depend on it.
| Parameter | Specification |
|---|---|
| Model | Masoneilan 5A Series double-acting cylinder actuator |
| Valve | Camflex II rotary globe valve, size 6 in. and above |
| Action | Double-acting piston, no spring; closes valve when stem retracts |
| Mounting | Left side of yoke; two positions only (vertical or horizontal to pipe) |
| Fail-safe provision | Air volume tank with transfer valve |
| Handwheel | Optional on both sides of yoke; usable as limit stop |
| Adjustment | Lever and plug fully closed, stem retracted; clevis pin and rod end bearing set |
| Key spares | Piston cylinder, piston stem, rod end bearing, inner and outer O-rings, limit stop |
Related Masoneilan products include the Masoneilan 35002 HC Camflex II high capacity valve, Masoneilan 35002 GR Camflex II globe replacement valve and Masoneilan Camflex II 35002 valve seal and packing kit.
Request a Quote for Masoneilan 5A
To request pricing or technical support for the Masoneilan 5A, send a formal RFQ to the Seven Star LLC instrumentation division with the Camflex II valve size and serial number, the pressure drop, the air supply pressure and the fail-safe action you need. We can confirm the configuration, advise on availability and lead time and supply the Baker Hughes manual linked on this page. In Oman and the GCC, Seven Star LLC supplies genuine actuators with manufacturer documentation and local engineering support.
- Instruction Manual Masoneilan 5A Cylinder Actuator Instruction Manual Download
Masoneilan control valves and actuator series
The globe valve listing centers on the 21000 series, including the cryogenic version with extension bonnet, and the 41005 cage-guided series in high pressure, API 6A and VRT anti-cavitation executions. The 80385 and 80386 are three-way combining and diverting valves. Rotary products include the 35002 Camflex II and the 37002 MiniTork II butterfly control valve. Actuators cover spring-diaphragm, cylinder and rack-and-pinion designs, among them the 5A cylinder actuator for Camflex II. Masoneilan also makes pressure regulators, SVI digital valve positioners and displacer-type level instruments, and offers Lo-dB trim for noise control.Where Masoneilan valves are used
Throttling duty on steam, hydrocarbons, gas and water is the daily work of these valves: feedwater and steam conditioning in power plants, separator and compressor loops in gas processing, high pressure drop letdown, cryogenic service in LNG and air separation, and general flow, pressure and level control in refineries and chemical plants.Ordering Masoneilan valves and spare parts: what we need
For spare parts the serial number is decisive, since the factory record behind it lists trim, materials and actuator. Send a clear nameplate photo with serial number, model number, size and pressure class. For a new valve add the process data: fluid, inlet and outlet pressure, temperature, minimum, normal and maximum flow, required leakage class, fail position, air supply and control signal.Browse Masoneilan products by category: Control Valves, Valve Actuator, Regulators, Valve Positioner, Level Transmitter.
Reviews
There are no reviews yet.