Masoneilan 31/32 Spring Diaphragm Rotary Actuators

Overview

The Masoneilan 31/32 is the Baker Hughes family of pneumatic spring diaphragm rotary actuators for quarter-turn control valves. Baker Hughes designed it to provide high performance, reliability and long service life, and the technical specification highlights a field-reversible air action, a modular spring pack, a separate interchangeable yoke, a molded rolling diaphragm and a high-power manual override option. In the Model 31 increasing air pressure rotates the output counter-clockwise, and in the Model 32 it rotates clockwise.

Seven Star LLC is the trusted supplier for Masoneilan in the Sultanate of Oman and supplies the Masoneilan 31/32 with the rotary valves it drives, as well as replacement actuators for existing installations. Our Muscat team can confirm the spring range and yoke adapter from the serial plate so that a replacement bolts straight onto the valve.

Operating Principle of the Masoneilan 31/32

In the Masoneilan 31/32, air pressure acts on a molded elastomeric diaphragm with a fabric insert, pushing a piston rod against one or two springs. The rod works a lever inside the ductile iron housing, converting the linear stroke into quarter-turn rotation of the valve shaft. Because the rolling diaphragm and deep cases keep the effective area almost constant, the relationship between travel, air pressure and output torque is more linear than in a flat-diaphragm design, which helps a positioner hold position accurately.

Three standard spring ranges are achieved with two springs used individually or combined: 12-28 psi, 17-40 psi and 29-68 psi (83 to 193, 117 to 276 and 200 to 469 kPa). The air action can be reversed in the field without extra parts, so one stocked actuator can serve air-to-open or air-to-close duty. In the Model 36 version described in the instruction manual the spring-diaphragm design is replaced by a double-acting piston.

Engineering Design of the Masoneilan 31/32

The housing and cover are ductile iron, the shaft and clevis pin are 17-4 PH stainless steel, and the upper and lower diaphragm cases are pressed steel that combines low weight with high mechanical strength and protection if the actuator is over-pressurized. The diaphragm is Buna-N with a polyester insert, the indicator pointer is stainless steel and the front cover is polycarbonate. The yoke is a separate part, so it can be a cast yoke adapter for Masoneilan rotary valves or a fabricated universal mounting with coupling, key and shaft for other quarter-turn designs.

The optional hand-jack override is a right-angle gear with an 8 in. (203 mm) aluminum handwheel and a jack screw assembly, and it is available on every configuration. Integral travel stops, a ball bearing and an indicator dot complete the linkage of the Masoneilan 31/32, and a yoke and mounting parts are available for Masoneilan rotary valves. Baker Hughes lists the weights as 183 lb (83 kg) without override and 194 lb (88 kg) with it for the cast yoke adapter, and 186 lb (84 kg) and 198 lb (90 kg) for the fabricated universal yoke.

Key Features

These are the points that make the Masoneilan 31/32 practical for plant maintenance teams:

• On the Masoneilan 31/32, air action is field reversible without additional parts, which reduces the spares that must be stocked.
• A modular spring pack provides three standard spring ranges from two springs used singly or combined.
• A separate interchangeable yoke allows flexible mounting on Masoneilan rotary valves and universal mounting on other quarter-turn valves.
• The molded rolling diaphragm with fabric insert gives long life, high sensitivity and a linear travel-to-torque relationship.
• Pressed steel diaphragm cases protect the actuator in the event of over-pressurization.
• An optional right-angle manual gear override is available on all configurations.
• The Model 31/32/36 family is designed for 35002 Camflex, 36005 V-Max, 37002 MiniTork and 39003/39004 butterfly valves.
• Baker Hughes states an estimated useful life of 25 years or more with annual inspection and routine maintenance.

Industrial Applications

The Masoneilan 31/32 drives rotary control valves in refinery, petrochemical, power and water treatment plants where a robust enclosed actuator is preferred, and the field-reversible action is useful for fail-safe positions that may change during a plant revamp. In Oman it is relevant to the process and utility plants in the Sohar and Salalah industrial zones, where Camflex and butterfly valves are common and where maintenance teams value a single actuator that can be reconfigured on site.

In Oman and the GCC, Seven Star LLC supplies the Masoneilan 31/32 with the valves it operates, such as the Masoneilan 35002 Camflex rotary control valve, the Masoneilan 37002 MiniTork II butterfly valve and the Masoneilan 39004 high performance butterfly valve. We also advise on positioner and handwheel selection for the finished assembly, so the Masoneilan 31/32 arrives configured for the valve and its control loop.

Technical Specifications

The table lists the published data for the Masoneilan 31/32 from the Baker Hughes technical specification, Rev. A, 09/2020. Torque values are output torque at the stated air supply.

Related Masoneilan products include the Masoneilan 36005 V-Max control ball valve, Masoneilan 39003 high performance butterfly valve and Masoneilan 87/88 handwheel and limit stop options.

Request a Quote for Masoneilan 31/32

To request pricing or technical support for the Masoneilan 31/32, send a formal RFQ to the Seven Star LLC instrumentation division with the valve model and size, the spring range, the required fail-safe action, the air supply pressure and whether a manual override is needed. We can confirm the configuration, advise on availability and lead time and supply the technical specification and manual linked on this page. In Oman and the GCC, Seven Star LLC supplies genuine actuators with manufacturer documentation and local engineering support.