Masoneilan 12830 Pneumatic Two-Position Differential-Gap Level Controller
Overview
The Masoneilan 12830 is a two-position pneumatic level controller. Baker Hughes lists it as a two-position differential-gap controller. Instead of an output that follows level continuously, it drives its output between two extremes and lets the level wander inside an adjustable band, the differential gap, before it switches back. This on-off style suits filling and emptying a tank, where a valve is either open or closed and a steady proportional output is not needed.
Seven Star LLC supplies the Masoneilan 12830 to process plants in Oman and the GCC. Because the gap width and position depend on the process, we ask for the vessel arrangement, specific gravity, displacer range and valve action, and supply the Baker Hughes manual so installers can set the gap correctly.
Operating Principle of the Masoneilan 12830
The sensing end matches the other 12800 models: a displacer on a torque tube moves a reversing arc, control link and control arm, and the arm positions a flapper against a nozzle. The difference is in the feedback. Baker Hughes states that the differential-gap controller is identical to the proportional controller except that the positions of the proportional bellows and bellows spring are reversed, which turns negative feedback into positive feedback.
With positive feedback, once the flapper begins to cover the nozzle the bellows pushes it further and the output is driven to one extreme. The level must then move a certain distance the other way before the flapper uncovers the nozzle. That distance is the differential gap, set by the position of the differential-gap clamp along the proportional spring, while the control setting fixes the middle of the gap.
Engineering Design of the Masoneilan 12830
The mechanism drawing of the Masoneilan 12830 lists the differential-gap clamp and differential-gap scale in place of the proportional band clamp and scale. Air supply is the one setting that differs: 18 psi for a 3-15 psi output range on differential-gap control, against 20 psi on proportional and proportional-reset controllers, and 35 psi for 6-30 psi output.
Air Piping for the Masoneilan 12830
The supply to the filter regulator must be clean, dry and held between 50 and 125 psi gauge, and the manual says to blow out all pipe, tubing and fittings before connecting. Where several controllers are grouped, a brass supply header of at least 1/2 in. is usual, with each connection made on the top or side of the header and never the bottom, and a shutoff valve and filter-regulator for each controller. Output air goes to the control valve in 1/4 in. brass or 3/8 in. O.D. copper tubing, which must be air-tight.
Direct and Reverse Action on the Masoneilan 12830
The controller leaves the factory set for the action specified, and the manual asks the installer to check it against the application. If a rise in level should close an air-to-close valve or open an air-to-open valve, the action is direct; if it should open an air-to-close valve or close an air-to-open valve, the action is reverse. The arrow on the reversing arc must point toward the displacer, the control link goes in the matching slot, and the control setting scale and knob plate must read D or R accordingly.
Setting the Gap on the Masoneilan 12830
With the displacer hanging free and supply at 18 psi, set the control link index to the specific gravity, the control setting index at 5 and the differential-gap index at 100 percent. Turn the alignment micrometer slowly until the output changes to 0 psi (direct action) or 18 psi (reverse action) and lock it at the point where the change just occurs. The desired gap is then dialled on the differential-gap scale. Finally admit process liquid and adjust the control setting to position the gap within the instrument range.
Converting a Proportional 12800 to the Masoneilan 12830
The change needs only a different bellows tubing assembly and, if desired, a differential-gap scale, because the proportional bellows assembly and the bellows spring assembly simply swap positions. Once both units are removed, the bellows slides into the position the spring held and the spring into the position the bellows held, new tubing links the bellows to the air manifold, the output gauge is refitted and the mechanism is aligned for differential-gap control with the supply at 18 psi.
Key Features
- Two-position control with an adjustable differential gap rather than a continuous output.
- Gap width is set on the differential-gap scale and gap position by the control setting index.
- The Masoneilan 12830 uses the same displacer, torque tube and reversing arc as the other 12800 models, so mounting and piping are unchanged.
- Direct or reverse action is chosen with the control link and arc slot.
- Runs on instrument air alone; level and interface service are both possible.
Industrial Applications
Two-position control suits duties where a valve fills or drains a vessel between two levels. The Masoneilan 12830 can manage a transfer tank or drain vessel with a pneumatic on-off valve, and the gap prevents the valve from chattering around a single set point. It is a mechanical alternative to an electrical level switch and solenoid at refineries, gas plants and utility systems in Sohar, Duqm and Salalah that still run pneumatic equipment.
Seven Star LLC can add the valves it operates, such as the Masoneilan 10000 series double-port valve and the Masoneilan Type 51/52/53 piston actuators.
Related published Masoneilan pages: Masoneilan Type 87/88 spring-diaphragm actuators.
Technical Specifications
Published data for the Masoneilan 12830 from the 12800 Series instruction manual.
| Parameter | Specification |
|---|---|
| Model | Masoneilan 12830 two-position differential-gap level controller |
| Control mode | Two-position with adjustable differential gap |
| Output and supply | 3-15 psi range on an 18 psi supply; 6-30 psi range on 35 psi |
| Gap adjustment | Differential-gap clamp on the proportional spring, read on the differential-gap scale |
| Gap position | Control setting index within the instrument range |
| Alignment start values | Control setting index 5; differential-gap index 100 percent |
| Alignment output | 18 psi direct action or 0 psi reverse action at zero level |
| Field conversion | Reverse the proportional bellows and bellows spring; new bellows tubing assembly |
Related Masoneilan level instruments include the Masoneilan 12800 Series pneumatic level controller, Masoneilan 12400 Series digital level transmitter, Masoneilan 12810 proportional-reset level controller, Masoneilan 12820 pneumatic level transmitter and Masoneilan 12840 pneumatic-set level controller.
Request a Quote for Masoneilan 12830
For pricing on the Masoneilan 12830, send an RFQ to the Seven Star LLC instrumentation division stating the displacer range, mounting type, specific gravity, required gap and valve action. We confirm the model, advise on availability and lead time and provide the Baker Hughes instruction manual from this page, backed by Seven Star LLC as trusted Masoneilan supplier in Oman and the GCC.
- Instruction Manual Masoneilan 12830 Level Controller 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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