Masoneilan 4700P/4800P Pneumatic Valve Positioner
Overview
The Masoneilan 4700P and its high-capacity sibling the Masoneilan 4800P are pneumatic valve positioners from Baker Hughes that make a control valve stroke in proportion to a pneumatic signal from a controller. Both use a precision feedback cam, which Baker Hughes describes as providing accurate positioning, fast response and customised control characteristics, and both fit rotary and reciprocating actuators. Because the positioner is entirely pneumatic, it needs no electrical power and no electrical certification of its own, which keeps it simple to install and maintain in remote and hazardous process areas.
Seven Star LLC is a trusted supplier for Masoneilan and supplies the Masoneilan 4700P family to refineries, gas plants, power stations and water utilities in the Sultanate of Oman and across the GCC. Our instrumentation team in Muscat can match the model code to the actuator and valve, confirm whether the standard-capacity 4700P or the high-capacity 4800P is the right choice for the stroking speed required, and supply the Baker Hughes instruction manual so that installers have the correct mounting and calibration data.
Operating Principle of the Masoneilan 4700P
The Masoneilan 4700P works on the force-balance principle. The pneumatic signal pressure acts on a diaphragm, and the force it creates is opposed by a feedback spring. When the signal changes, the diaphragm assembly moves and the pilot plug follows it against the pilot spring. The pilot is essentially a three-way sliding valve: its plug connects the output circuit either to the air supply or to the exhaust port, so the pressure sent to the actuator rises or falls.
The cam closes the loop. It carries the movement of the valve plug to the feedback spring, and the valve keeps moving until the spring force exactly balances the force of the instrument signal on the diaphragm. In the new balanced state the valve is positioned in a programmed relationship to the signal. The profile of the cam defines that relationship, which is why the same positioner can deliver linear, split-range linear or equal percentage behaviour simply by selecting a different lobe, and why custom characteristics are available on special order.
Engineering Design of the Masoneilan 4700P
The instrument is built around a cast body with a snap-on cover, and the internal materials are chosen to resist corrosion in harsh environments. All adjustments are fully enclosed, the pilot valve is the only moving component in the pilot housing, and it can be removed without disassembling the rest of the positioner. Zero is set with an adjustable spring button and turnbuckle assembly, and a damping adjustment stabilises the travel speed of the actuator. The numbering system tells the installer what has been supplied: the first digit separates standard capacity (7) from high capacity (8), the second gives the signal span of 3-15 psi or 6-30 psi, the third gives rotary or reciprocating mounting, and the last letter P marks the pneumatic version.
A feature specific to the pneumatic family is reversible action. The Masoneilan 4700P can be changed from direct to reverse acting without additional parts by interchanging the supply and exhaust connections and changing the cam lobe and lever arm orientation, so the control signal can either open or close the valve. The direct-acting 4700P can also be fitted with an optional molded nylon bypass valve with an O-ring seal. Turning it to the bypass position isolates the positioner so that the valve can be driven directly by the instrument signal while the pilot is cleaned.
Key Features
These characteristics explain why the Masoneilan 4700P remains a standard accessory on Masoneilan actuators and valves:
- Multi-lobe cam with field-changeable linear, split-range linear and equal percentage characteristics, with custom profiles on request.
- Force-balance design with no electronics, so no power supply, wiring or electrical approval is needed on the positioner itself.
- Reversible action on the pneumatic models, allowing the same hardware to be used for air-to-open or air-to-close service.
- Optional concealed nylon bypass valve on the direct-acting 4700P so that control can continue manually during pilot cleaning.
- Damping adjustment to stabilise actuator travel speed on large or fast actuators.
- Fully enclosed adjustments and corrosion-resistant internal materials for harsh process environments.
- Split-range operation for sequencing two valves from a single controller signal.
- Mounting arrangements for Masoneilan Type 87/88 actuators, Camflex II, V-Max, MiniTork II and butterfly valves.
Industrial Applications
The Masoneilan 4700P is chosen where a robust, low-maintenance positioner is wanted on pneumatic actuators: refinery and gas plant control valves, steam and condensate service in power stations, cooling water and utility systems, and process lines in petrochemical complexes. Baker Hughes notes that the family is intended for industrial compressed air or natural gas supply, and that natural gas installations are Zone 0 or Division 1 installations. Typical Omani sites include the Sohar and Duqm industrial zones and the oil and gas fields inland, where the lack of electronics is an advantage in hot, dusty conditions.
In Oman and the GCC, Seven Star LLC supplies the Masoneilan 4700P alongside the valves and actuators it controls. It mounts directly on Masoneilan Type 87/88 spring-diaphragm actuators and on rotary valves such as the Masoneilan Camflex II 35002 rotary control valve and the Masoneilan MiniTork II butterfly control valve. If your loop receives a 4-20 mA signal, ask us about the electropneumatic 4700E and 4800E versions instead.
Technical Specifications
The table gives the published data for the Masoneilan 4700P and 4800P as listed in the Baker Hughes instruction manual. Please refer to the current manual for mounting data and parts lists.
| Parameter | Specification |
|---|---|
| Model | Masoneilan 4700P (standard capacity) and 4800P (high capacity) pneumatic positioners |
| Signal span | 3-15 psi or 6-30 psi |
| Action | Direct or reverse (reverse by changing connections, cam lobe and lever arm) |
| Characteristics | Linear, split-range linear, equal percentage, custom on request |
| Mounting | Rotary or reciprocating; 87/88 actuators, Camflex II, V-Max, MiniTork II, butterfly valves |
| Air consumption | 0.3 scf/min at 25 psig (4700P); 0.5 scf/min at 25 psig (4800P) |
| Supply pressure influence | Less than 0.25 percent stroke change per psi |
| Maximum supply rating | Dictated by the actuator, never above 100 psig |
| Pneumatic connections | 1/4 inch NPT (4700P); 3/8 inch (4800P) |
| Deadband and hysteresis | Less than 0.2 percent of span |
| Repeatability | Within 0.2 percent of span |
| Conformity | Plus or minus 1 percent of span |
| Weight | 1.6 kg (4700P); 1.9 kg (4800P) |
| Optional accessory | Nylon bypass valve with O-ring seal (direct-acting 4700P only) |
Related Masoneilan positioners and accessories include the Masoneilan 4700E/4800E electropneumatic positioner, Masoneilan SVi1000 digital valve positioner, Masoneilan 78 air filter regulator and Masoneilan BR400 volume booster relay.
Request a Quote for Masoneilan 4700P
To request pricing or technical support for the Masoneilan 4700P or the 4800P, send a formal RFQ to the Seven Star LLC instrumentation division stating the actuator type, valve action, signal span and mounting. We can confirm the model code, advise on availability and lead time and provide the Baker Hughes instruction manual from this page. In Oman and the GCC, Seven Star LLC delivers genuine products with manufacturer documentation and local engineering support.
- Instruction Manual Masoneilan 4700P/4700E and 4800P/4800E Positioners 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.