Masoneilan 7700P and 7700E Positioners for Varipak Valves
Overview
The Masoneilan 7700P and its electro-pneumatic sibling the 7700E are the positioners Baker Hughes fits to its 28000 Series Varipak microflow control valves. They use a force-balance mechanism: a pneumatic signal acts on a double diaphragm, and an opposing force from a feedback spring changes with the movement of the actuator lever. The valve is positioned where the two forces are equal. The 7700P takes the pneumatic signal directly, while the 7700E adds a Model 4000 I/P converter in the manifold block so that it can work from a 4-20 mA loop.
Seven Star LLC is the trusted supplier for Masoneilan in the Sultanate of Oman and supplies the Masoneilan 7700P and 7700E with Varipak valves and as replacements for existing units. Our Muscat engineers can confirm housing material, cable entry, mounting code and hazardous area marking from the nameplate.
Operating Principle of the Masoneilan 7700P
The Masoneilan 7700P is a single unit with different versions rather than a family of models. Housing material can be aluminum or stainless steel, and the mounting can be a single lever (28001) or an adjustable Cv arrangement (28002). Baker Hughes quotes performance as a percentage of the signal range: a start point (closed valve) of 2.0 percent or better and hysteresis at mid-stroke of 0.9 percent or better.
Calibration of the Masoneilan 7700P on site follows a simple routine: connect the pneumatic lines, supply air no higher than the pressure shown on the serial plate and never above 275 kPa (40 psi), and use the take-up screw (K116) to set the starting pressure, turning it until the piston rod just begins to move and the plug leaves its seat at a 3-15 psi or 6-30 psi signal. The locknut (K117) is then tightened. A positioner assembled on a valve is factory calibrated.
Engineering Design of the Masoneilan 7700E
In the 7700E, the Model 4000 I/P converter generates the pneumatic signal for the double diaphragm. The positioner is self-powered from the 4-20 mA signal with an input impedance of 170 ohms, and terminals accept wire up to AWG 14 with internal and external ground connections. The cable entry is 1/2 inch NPT or M20, and the manual identifies the two converter versions by part number sticker: 00-055100106-888 for M20 and 00-055100212-888 for 1/2 inch NPT. The housing is IP66 / Type 4X.
The ATEX markings under certificate ITS-I21ATEX29368X cover intrinsic safety (Ex ia IIC T6 Ga to 55 degC with 0.33 W, Ex ia IIC T4 Ga to 80 degC with 1.1 W, and Ex ia IIIC Da T90 degC) and flameproof (Ex db IIC T6, T5 and T4 Gb up to 55, 70 and 85 degC, and Ex tb IIIC T90 degC Db). Warnings state that the cover must not be opened when energized or when an explosive gas atmosphere is present, and that the cover seal and safety screw must be fitted before power is switched on. The flameproof version can be installed in flammable gas groups IIA, IIB and IIC in zones 1 and 2, or in dust group IIIC zones 21 and 22, with a maximum power of 0.8 W. Where cable glands use adaptors or reducers, the manual calls for taper threaded joints to ANSI/ASME B1.20.1 with five threads engaged on each part, cemented with a thread locker such as Loctite Freinfilet Fort or equivalent.
Key Features
These are the points that make the Masoneilan 7700P and 7700E worth specifying on Varipak valves:
- The Masoneilan 7700P uses a simple force-balance double-diaphragm design with few moving parts.
- The 7700E is self-powered from a 4-20 mA signal and needs no separate supply.
- On the Masoneilan 7700P housing is available in aluminum or stainless steel for different corrosion duties.
- Mounting options are single lever 28001 or adjustable Cv 28002.
- ATEX intrinsic safety and flameproof markings are provided for gas and dust zones 0, 1, 2, 20, 21 and 22 depending on version.
- Start point is 2.0 percent or better and hysteresis 0.9 percent or better of the signal range.
- Service temperature is -40 to +85 degC, with storage down to -55 and up to +90 degC.
- For the Masoneilan 7700P, tubing of 4 x 6 mm and a maximum air supply of 275 kPa (40 psi) keep installation straightforward.
Industrial Applications
The Masoneilan 7700P and 7700E position Varipak microflow valves, which are used where very small flows must be controlled precisely. In Oman the 7700E is the more relevant version for classified areas in refinery, gas processing and petrochemical plants around Sohar and Duqm, where an intrinsically safe or flameproof positioner is required.
In Oman and the GCC, Seven Star LLC supplies the Masoneilan 7700P with the Masoneilan 28000 Series Varipak valve, and our engineers can confirm which Masoneilan 7700P or 7700E version and mounting match the Varipak valve you order, including whether the 28001 single lever or 28002 adjustable Cv bracket is needed. Where a digital positioner is preferred we can compare the 7700E with the SVI family.
Related published Masoneilan pages: Masoneilan SVI3 digital valve positioner and Masoneilan 10000 Series double-port valve.
Technical Specifications
The table lists the published data for the Masoneilan 7700P and 7700E from the Baker Hughes manuals (7700P Rev. A; 7700E ATEX 2025).
| Parameter | Specification |
|---|---|
| Model | Masoneilan 7700P (pneumatic) and 7700E (electro-pneumatic, I/P 4000 module) |
| Principle | Force balance: double diaphragm against feedback spring |
| Housing material | Aluminum or stainless steel |
| Mounting | Single lever 28001 or adjustable Cv 28002 |
| Signal calibration (7700P) | 3-15 psi or 6-30 psi |
| Input signal (7700E) | 4-20 mA, self-powered; input impedance 170 ohms |
| Air supply | Per serial plate, not to exceed 275 kPa (40 psi); tubing 4 x 6 mm |
| Start point | 2.0 percent or better of signal range |
| Hysteresis | 0.9 percent or better at mid-stroke |
| Service temperature | -40 to +85 degC; storage -55 to +90 degC |
| Protection (7700E) | IP66 / Type 4X |
| Cable entry (7700E) | 1/2 inch NPT or M20; wire up to AWG 14 |
| ATEX certificate (7700E) | ITS-I21ATEX29368X; II 1GD (Ex ia) and II 2GD (Ex db, Ex tb) |
Related Masoneilan products include the Masoneilan 28000 MS Varilog microflow valve, Masoneilan 28000 HP high pressure Varipak valve and Masoneilan 4700E/4800E electropneumatic positioner.
Request a Quote for Masoneilan 7700P
To request pricing or technical support for the Masoneilan 7700P or 7700E, send a formal RFQ to the Seven Star LLC instrumentation division with the Varipak valve model, the signal type, the housing material, the cable entry and the hazardous area classification you need. We can confirm the numbering, advise on availability and lead time and supply the Baker Hughes manuals linked on this page. In Oman and the GCC, Seven Star LLC supplies genuine instruments with manufacturer documentation and local engineering support.
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.
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