Masoneilan 12800 Series Pneumatic Level Transmitter/Controller

Overview

The Masoneilan 12800 Series is a family of pneumatic level controllers and transmitters from Baker Hughes that control or transmit the level in a tank holding one or two fluids, the second case being interface service. Each instrument is driven by a displacer and torque tube, needs no electrical power and delivers a 3-15 psi or 6-30 psi pneumatic output, so it can operate a control valve directly or send a level signal to a pneumatic receiver. Baker Hughes lists it as a current Masoneilan product for refining and petrochemical applications, and its operating manual was reissued in 2022 under the Baker Hughes brand from the earlier Masoneilan document.

Seven Star LLC is a trusted supplier for Masoneilan and supplies the Masoneilan 12800 Series to refineries, gas plants and petrochemical facilities across the Sultanate of Oman and the GCC. Our instrumentation team in Muscat helps customers select the correct controller mode, chamber arrangement, displacer length and materials, and provides the Baker Hughes instruction manual from this page for installers.

Operating Principle of the Masoneilan 12800 Series

The Masoneilan 12800 Series uses a level measuring element that converts the change in liquid level into a small mechanical movement. A displacer hangs from a torque arm, and as level rises the buoyant force reduces the load on the torque tube, which rotates a reversing arc. The arc carries a link to a control arm, and the movement positions a flapper against a nozzle. A pneumatic relay amplifies the resulting nozzle pressure into the output signal, with a ratio such that about 3.5 psi change at the nozzle gives a 12 psi output change, which is the full 3-15 psi span.

The reversing arc also serves as the means of choosing direct or reverse action and as the adjustment for specific gravity. Setting the control link index to the specific gravity of the liquid, or the specific gravity difference in interface service, makes a unit change in level produce the same primary motion for any liquid in range. The standard controller and displacer can be used with gravities, or gravity differences, as low as 0.1. A proportional bellows and spring then feed back a share of the output pressure so that the output is exactly proportional to the level movement across the chosen proportional band.

Engineering Design of the Masoneilan 12800 Series

The Masoneilan 12800 Series comes in five Baker Hughes model numbers that share the same measuring element but differ in the unit that converts motion into pressure. The 12800 is a proportional controller, the 12810 adds reset action to give proportional-reset control, the 12820 is a pneumatic level transmitter, the 12830 is a two-position differential-gap controller and the 12840 is a proportional controller whose set point is positioned pneumatically. Duplex instruments are also possible, with two separate controller mechanisms in one case actuated by a common torque tube and adjusted individually.

Mechanically, chamber-type models are mounted vertically on the side of the vessel, with the mid-range mark at normal level, equalising lines of the same size as the chamber connections and block valves in each line. Internal displacers hang inside the vessel, with a guide bracket or a stilling well where liquid is in motion or turbulent. According to Baker Hughes, measuring ranges run from 14 to 120 inches (355 to 3,048 mm), with flanged connections from ANSI 150 to 2500 and DIN PN 10 to 100, screwed 1 1/2 and 2 inch NPT-F and welded options. Body materials are carbon steel, stainless steel or chrome-moly, the displacer is stainless steel and the torque tube is Inconel or stainless steel.

Key Features

The following characteristics explain why the Masoneilan 12800 Series remains in use where a self-contained, air-only level instrument is wanted:

• Pneumatic operation from instrument air alone, with no electrical supply or wiring at the instrument.
• Five modes in one family: proportional, proportional-reset, transmitter, differential-gap and pneumatic-set controllers.
• Level and interface service, with specific gravity adjustment on the reversing arc.
• Direct or reverse action selected by the link position in the reversing arc, with a chart relating level, valve action and slot.
• Adjustable proportional band, with reset rate in repeats per minute on the 12810 and a differential-gap scale on the 12830.
• Remote set point on the 12840 from a 3-15 psi signal, where 3 psi corresponds to low level and 15 psi to high level.
• Range from 14 to 120 inches with chamber or internally mounted displacers.
• Estimated useful life of more than 25 years when annual inspection and routine maintenance are carried out, according to Baker Hughes.

Industrial Applications

Baker Hughes lists the Masoneilan 12800 Series for refining and petrochemicals, with applications that include distillation, hydroprocessing, reforming, cracking, secondary processes, blending, quenching, fractionation, charge gas compression and separation. In these services the controller holds the level of a separator, accumulator or column bottom by driving a control valve, while the transmitter version sends the level to a pneumatic receiver. In Oman, typical sites are refinery and gas processing units at Sohar and Duqm, including spare and replacement requirements for existing pneumatic loops.

In Oman and the GCC, Seven Star LLC supplies the Masoneilan 12800 Series with the valves that complete the loop. A level controller of this kind commonly operates a control valve such as the Masoneilan 41005 cage-guided control valve or the Masoneilan 10000 double-port control valve on a Masoneilan Type 87/88 spring-diaphragm actuator. Where a digital instrument is preferred, ask us about the Masoneilan 12400 Series digital level transmitter. Our engineers will confirm the mode, range and connection details for the Masoneilan 12800 Series.

Technical Specifications

The table summarises the published data for the Masoneilan 12800 Series from the Baker Hughes product page and instruction manual. The manual states that the clean, dry supply air must be held between 50 and 125 psi at the filter regulator.

Request a Quote for Masoneilan 12800

To request pricing or technical support for the Masoneilan 12800 Series, send a formal RFQ to the Seven Star LLC instrumentation division with the controller mode, measuring range, specific gravity or interface data, process pressure and temperature, and connection type. We can confirm the correct model, advise on regional stock 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.