Masoneilan 78-80S Transfer Valve with 08-80S Three-Way Transfer Valve
Overview
The Masoneilan 78-80S is a standard-capacity, three-way transfer valve of the set-pressure regulating type. Baker Hughes builds it by combining two functions in one unit: a pilot valve of the floating-ball type and a three-port valve. A companion model, the Masoneilan 08-80S, is the same valve without the pilot, so it is the plain three-way transfer valve. The two are designed to work together, because one 78-80S can carry the pilot function for several 08-80S valves, which saves piping when a skid or panel needs the same transfer action in more than one place.
Seven Star LLC is a trusted supplier for Masoneilan and supplies the Masoneilan 78-80S and 08-80S to maintenance and project customers in the Sultanate of Oman and the GCC. The pneumatic hardware around a control valve is often ordered late, and our Muscat team can confirm the set pressure, the port threading and the temperature option so that the valve arrives ready to fit, with the Baker Hughes instruction manual for the installers.
Operating Principle of the Masoneilan 78-80S
The Masoneilan 78-80S compares a signal pressure with a set pressure that is dialled in on the adjust knob. While the signal is higher than the set pressure the valve connects the IN port to the OUT port. When the signal falls below the set pressure, or reaches zero, the valve cuts off IN and connects OUT to the EXH port instead. The change of state is therefore a clean pressure-dependent switch between supplying a downstream circuit and exhausting it.
The floating-ball pilot is what gives the valve its set-pressure behaviour. A ball temporarily floats to transfer the pilot part, and Baker Hughes notes that the valve may emit a light beating tone at the moment the set and signal pressures become equal. This is described as normal and it stops when the transfer is complete. If the valve is used as a lock-up valve, a blind plug is fitted in the EXH port so that the outlet is not vented.
Engineering Design of the Masoneilan 78-80S
The body of the Masoneilan 78-80S is anodized die-cast aluminium alloy (ADC 12), with a chromated housing, spring case and bottom cap in the same alloy. The piston and plug sit in the body, a stainless steel exhaust orifice and a stainless steel ball serve the pilot, and the diaphragm is NBR and polyester. The adjust knob and the spacer are molded in VALOX 420, and the springs, lock screw and screws are stainless steel or spring steel. Two SUS304 stainless steel filters are fitted in the body.
The pilot part has two air connections, one marked SIG and the other SIG OUT. The signal pressure is connected to SIG, and SIG OUT is used to pass the signal on to the pilot port of an 08-80S. The IN, OUT, EXH and signal ports are threaded Rc 1/4, with an NPT 1/4 option. Installation notes in the manual call for clean pipes, mounting as close to the actuator as possible with air flowing toward the IN and OUT marks, and signal pressure that is not taken from near the IN side of the body, which could cause fluctuation and hunting.
Key Features
The following points describe how the Masoneilan 78-80S is used in practice:
- It combines a floating-ball pilot valve and a three-port valve in a single compact unit.
- The set pressure range of 100 kPa to 700 kPa is adjusted with a knob and secured with a lock screw.
- One Masoneilan 78-80S can drive several 08-80S valves by connecting its pilot output to their signal ports.
- The OUT-to-exhaust path has a higher flow coefficient than the supply path, which helps the downstream circuit vent quickly.
- With a blind plug in the EXH port the valve can serve as a lock-up valve.
- Hysteresis is limited to 34 kPa or less, which keeps the changeover point repeatable.
- Operating temperature extends from -30 degC to +83 degC, with an option of 0 degC to +100 degC.
- The instruction manual lists certification in several jurisdictions and ATEX compliance for use in regulated areas.
Industrial Applications
Transfer valves of this kind are used in pneumatic circuits that must switch automatically between two states when a signal pressure passes a set value. The Masoneilan 78-80S suits valve control packages, protection circuits and air manifolds around pneumatic final elements in oil and gas processing, power generation and water facilities, including installations at Sohar, Duqm and Salalah. It is selected where a mechanical, air-only changeover is preferred to an electrical one.
In Oman and the GCC, Seven Star LLC supplies the Masoneilan 78-80S with the equipment it protects, including the Masoneilan Type 87/88 actuators and the Masoneilan Type 51/52/53 piston actuators. For the same air line, the Masoneilan BR200 booster relay supplies extra volume, and our engineers will help you match the right transfer, lock-up or booster accessory to each valve.
Technical Specifications
The table lists the Baker Hughes data for the Masoneilan 78-80S and the 08-80S from the instruction manual.
| Parameter | Specification |
|---|---|
| Model | Masoneilan 78-80S (with pilot) and 08-80S (without pilot) |
| Type | Standard-capacity three-way transfer valve, set-pressure regulating type |
| Maximum operating pressure | Body 1.72 MPa; signal part 1.03 MPa |
| Set pressure range | 100 kPa to 700 kPa |
| Hysteresis | 34 kPa or less |
| Cv value | IN to OUT 0.8; OUT to EXH 1.3 |
| Connections | IN, OUT, EXH and signal ports Rc 1/4 (option NPT 1/4) |
| Operating temperature | -30 degC to +83 degC (option 0 degC to +100 degC) |
| Body and housing | ADC 12, anodized or chromated |
| Pilot ball | SUS440C stainless steel |
| Diaphragm | NBR and polyester |
| Recommended rubber renewal | Every five years |
Related Masoneilan accessories include the Masoneilan 78 air filter regulator, Masoneilan BR400 volume booster relay and Masoneilan 4411 I/P transducer.
Request a Quote for Masoneilan 78-80S
To request pricing or technical support for the Masoneilan 78-80S or 08-80S, send a formal RFQ to the Seven Star LLC instrumentation division stating the required set pressure, port thread, temperature range and quantity. We can confirm the model, 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 78-80S Transfer Valve 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.
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