Masoneilan 4700E/4800E Electropneumatic Valve Positioner

Overview

The Masoneilan 4700E is the electropneumatic version of the Baker Hughes cam positioner, built for control loops that deliver a 4-20 mA signal rather than a pneumatic one. Together with its high-capacity counterpart the Masoneilan 4800E, it takes the current signal from the controller, converts it to pressure with an integral current-to-pressure module and uses the same precision feedback cam as the pneumatic models to position rotary or reciprocating control valves. The result is a positioner that accepts a standard electronic signal while keeping the mechanical position feedback that Masoneilan customers rely on.

Seven Star LLC is a trusted supplier for Masoneilan and supplies the Masoneilan 4700E to oil and gas, power and process customers across the Sultanate of Oman and the GCC. Our instrumentation division in Muscat checks the signal span, mounting, actuator action and hazardous area rating before quotation, because the electropneumatic models have constraints, such as the absence of reverse action, that must be understood at the specification stage.

Operating Principle of the Masoneilan 4700E

The Masoneilan 4700E combines two stages. In the first, an I/P module converts the 4-20 mA input into a pneumatic signal. In the second, that pressure acts on the positioner diaphragm, where it is balanced against a feedback spring in the same way as in the pneumatic 4700P. Any change of signal moves the diaphragm assembly and the pilot plug, which connects the output either to supply air or to exhaust, and the valve moves until the cam-driven feedback spring balances the force from the signal.

Because the signal is converted before it reaches the diaphragm, the valve position is still determined by the mechanical cam. Selecting a cam lobe gives a linear, split-range linear or equal percentage relationship between current and travel, and cams supplied on butterfly valves maintain the inherent characteristic of the valve. Baker Hughes states that the electropneumatic 4700E and 4800E are not available with reverse action; if an application needs an electropneumatic positioner with reverse action, a pneumatic 4700P or 4800P with an external I/P transducer must be used instead.

Engineering Design of the Masoneilan 4700E

Electrically, the Masoneilan 4700E presents a nominal 170 ohm input resistance, accepts wire up to AWG 14 on its terminals, and is normally supplied with a 1/2 inch NPT conduit entry, with M20 as an option. The loop controller must be able to drive 4-20 mA with at least 5 Vdc of output compliance, and Baker Hughes warns that a voltage source must never be used because it can cause permanent damage. The electrical parts are isolated from ground, with internal and external ground terminals available where installation codes require grounding.

The pneumatic side follows the 4700 and 4800 numbering: the first digit gives standard capacity or high capacity, the second digit 0 denotes the 4-20 mA signal, the third digit gives rotary or reciprocating mounting and the final letter E marks the electropneumatic type. The instrument has a cast body and a snap-on plastic or metal cover over the enclosed zero, span and damping adjustments. The Masoneilan 4700E weighs 2.1 kg and the 4800E 2.4 kg, and the maximum supply pressure is dictated by the actuator but never above 100 psig.

Key Features

The following points distinguish the Masoneilan 4700E from the pneumatic versions and from smart digital positioners:

• Direct 4-20 mA input with an integral I/P module, so no external transducer or tubing is needed on the valve.
• Mechanical cam feedback with field-changeable linear, split-range linear and equal percentage lobes.
• Hazardous area versions with flameproof and intrinsically safe marking under ATEX certificate ITS-I21ATEX29368X, plus FM and CSA approvals.
• Terminals for wire to AWG 14 and a 1/2 inch NPT conduit entry, with an M20 entry as an option.
• Zero, span and damping adjustments are enclosed behind a snap-on cover, protected from the environment.
• Split-range operation so that two valves can share one 4-20 mA signal.
• Standard capacity (4700E) and high capacity (4800E) versions for different actuator volumes.
• Direct-acting operation, with reverse action available only on the pneumatic 4700P and 4800P.

Industrial Applications

The Masoneilan 4700E suits loops where the control system provides an analogue current output and the plant wants a proven mechanical positioner rather than a software-configured one. Typical uses include steam and feedwater control valves in power plants, hydrocarbon process valves in refineries, and utility service in petrochemical and gas plants. Where the area is classified, the approvals listed in the Baker Hughes manual cover flameproof, intrinsically safe and non-incendive installations, so the correct version must be selected for each zone and gas group.

In Oman and the GCC, Seven Star LLC supplies the Masoneilan 4700E with the valves it controls, including the Masoneilan Type 87/88 actuators and Masoneilan Type 51/52/53 piston actuators. When a plant wants HART diagnostics instead of a mechanical cam, we can propose the Masoneilan SVI3 digital valve positioner. Our team will review the loop details and recommend the right option for facilities in Sohar, Salalah and Duqm.

Technical Specifications

The table summarises the published data for the Masoneilan 4700E and 4800E. Refer to the Baker Hughes instruction manual for approvals, drawings and parts.

Related Masoneilan positioners and accessories include the Masoneilan 4700P/4800P pneumatic positioner, Masoneilan 4411 I/P transducer and Masoneilan SVi1000 digital valve positioner.

Request a Quote for Masoneilan 4700E

To request pricing or technical support for the Masoneilan 4700E or the 4800E, send a formal RFQ to the Seven Star LLC instrumentation division stating the actuator, signal span, hazardous area classification and cable entry. We can confirm the correct 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.