Masoneilan Model 51 Double-Acting Actuator, Sizes 12 to 46 with Volume Tank Option
Overview
The Masoneilan Model 51 double-acting actuator is the spring-less member of the Baker Hughes 51/52/53 series. Air is applied to both sides of the piston, so the actuator moves the stem in either direction with full cylinder thrust and without the thrust loss a spring takes out of single-acting designs. The technical specification lists thirteen sizes: 12, 16, 16L, 20, 20L, 24, 24L, 28, 28L, 32, 32L, 40 and 46, with cylinder diameters from 305 mm to 815 mm, a maximum thrust of 388,400 N (87,316 lbf) on size 40 and strokes from 0.25 in. to 30 in. in 0.25 in. steps.
In Oman and the GCC, Seven Star LLC supplies the Masoneilan Model 51 double-acting actuator to refineries, gas plants, power stations and water utilities in Oman and the GCC. Because there is no spring, fail action is not built in; Baker Hughes offers an integral volume tank for sizes 12, 16, 20, 24L, 28L and 32L, and the buyer chooses between a tank, a separate air failure system or an override according to the valve’s safe position.
Masoneilan Model 51 Double-Acting Actuator: Thrust and Area by Size
| Size | Cylinder diameter | Piston type | Maximum thrust | Maximum stroke |
|---|---|---|---|---|
| 12 | 305 mm | Single | 50,232 N (11,293 lbf) | 4 in. (101.6 mm) |
| 16 | 386 mm | Single | 80,661 N (18,133 lbf) | 12 in. (304.8 mm) |
| 16L | 386 mm | Single | 80,661 N (18,133 lbf) | 30 in. (762 mm) |
| 20 | 488 mm | Single | 128,961 N (28,992 lbf) | 12 in. (304.8 mm) |
| 20L | 488 mm | Single | 128,961 N (28,992 lbf) | 30 in. (762 mm) |
| 24 | 386 mm | Double | 123,066 N (27,666 lbf) | 12 in. (304.8 mm) |
| 24L | 572 mm | Single | 177,054 N (39,803 lbf) | 30 in. (762 mm) |
| 28 | 488 mm | Double | 197,266 N (44,347 lbf) | 12 in. (304.8 mm) |
| 28L | 705 mm | Single | 269,307 N (60,543 lbf) | 12 in. (304.8 mm) |
| 32 | 574 mm | Double | 256,750 N (57,720 lbf) | 12 in. (304.8 mm) |
| 32L | 815 mm | Single | 359,904 N (80,910 lbf) | 12 in. (304.8 mm) |
| 40 | 705 mm | Double | 388,400 N (87,316 lbf) | 6 in. (152.4 mm) |
Size 46 appears in the stroke, dimension and weight tables (stroke up to 6 in.) but has no thrust line. “L” denotes the long-stroke or large-bore single-piston version. Thrust figures are Baker Hughes maxima and do not replace a valve thrust calculation.
Fail Action of the Masoneilan Model 51 Double-Acting Actuator
Without springs the Masoneilan Model 51 double-acting actuator cannot return a valve to a safe position on loss of air by itself. The optional integral volume tank stores air at supply pressure to push the piston to the fail position. Standard volumes are 4.3 US gal (16.2 L) for size 12, 6.5 gal for size 16, 9.8 gal for size 20, 14.2 gal for size 24L, 21.6 gal for size 28L and 28.8 gal (109.6 L) for size 32L. In the model code the option is “V”. The tank adds weight: a size 12 weighs 179 lb (81 kg) standard and 280 lb (127 kg) with the tank, and a size 16 weighs 386 lb and 578 lb. The adjustable travel stop is available only without a volume chamber.
Adjustable Travel Stops and Strokes of the Masoneilan Model 51 Double-Acting Actuator
A single adjustable stop, up or down but never both, can be supplied on sizes 12 to 32. A size 16 at 2.5 in. stroke can have an up stop adjusting valve opening from 0 to 100 percent and a down stop from 0 to 50 percent; at 6 in. the up stop covers 50 to 100 percent. Size 12 supports strokes up to 4 in., sizes 16, 20, 24, 28 and 32 up to 12 in., sizes 40 and 46 up to 6 in., and sizes 16L, 20L and 24L up to 30 in. For the L sizes, 40 and 46 the stop can be developed on demand.
Air Connections of the Masoneilan Model 51 Double-Acting Actuator
Standard air connections are 3/4 in. NPT on the top plate and yoke on every size, with 1/2 in. or 3/4 in. NPT at the separator plate depending on size. The standard yoke offers spud diameters from 2.25 in. to 7.25 in., and stem sizes run from 0.5 in. (size 12 only) to 1.63 in. (sizes 24 and above). The split-clamp positioning gap SB is 125 mm on size 12, 109 mm on size 16 and 115 mm on sizes 20 to 46.
Materials of the Masoneilan Model 51 Double-Acting Actuator
Standard construction of the Masoneilan Model 51 double-acting actuator uses nitrile (Buna-N) O-rings and rod scraper, a graphite-PTFE guide ring and a PTFE-on-steel guide bushing. Options include low-temperature service to −46°C or −50°C with low-temperature steels, and high-temperature service to +100°C with high-temperature nitrile. The piston sits in a separate cylinder chamber, so dynamic seals can be replaced without dismantling the whole assembly, and the series conforms to the European Pressure Equipment Directive.
Key Features
- Masoneilan Model 51 double-acting actuator in thirteen sizes from 12 to 46
- Full thrust in both directions, up to 388,400 N
- Strokes from 0.25 in. to 30 in.
- Integral volume tank option for fail action on sizes 12 to 32L
- CM or DM handwheel and a single adjustable travel stop
Industrial Applications
Choose the Masoneilan Model 51 double-acting actuator when the process needs thrust in both directions and fail action is handled by a tank or the control system: large control valves and on-off duties in refineries, gas plants, power stations and water utilities. The complete family is on the Type 51/52/53 piston actuator page.
Related Masoneilan actuator pages: Masoneilan Model 52/53 spring-return actuators, Masoneilan 50 Series soft goods kits and Masoneilan 51/52/53 manual override.
Related published Masoneilan pages: Masoneilan 10000 Series double-port valve and Masoneilan Type 87/88 spring-diaphragm actuators.
Technical Specifications
The table lists the data Baker Hughes publishes for the Masoneilan Model 51 double-acting actuator.
| Parameter | Specification |
|---|---|
| Model | Masoneilan Model 51 double-acting actuator (cylinder type, no springs) |
| Manufacturer | Masoneilan (Baker Hughes) |
| Sizes | 12, 16, 16L, 20, 20L, 24, 24L, 28, 28L, 32, 32L, 40, 46 |
| Cylinder diameter | 305 mm (size 12) to 815 mm (size 32L) |
| Maximum thrust | 50,232 N (size 12) to 388,400 N (size 40) |
| Stroke | 0.25 in. increments up to 30 in. depending on size |
| Option code | V = integral volume chamber |
| Integral volume tank sizes | 12, 16, 20, 24L, 28L, 32L (4.3 to 28.8 US gal) |
| Air connections | 3/4 in. NPT top and yoke |
| Manual override | CM handwheel (12), DM handwheel (16, 20, 24, 28, 32) |
| Source documents | 51/52/53 Technical Specifications Rev. J (10/2024); 51/52/53 Instruction Manual Rev. E |
Request a Quote for Masoneilan Model 51 double-acting actuator
Send Seven Star LLC an RFQ for the Masoneilan Model 51 double-acting actuator with the valve model, stem size, required thrust and stroke, supply pressure and fail action, including any integral volume tank. In Oman and the GCC, we check the configuration against the Baker Hughes technical specification linked on this page and arrange delivery from Muscat.
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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