Masoneilan 8007 Series Electro-Pneumatic Transducer (8007/8008)
Overview
The Masoneilan 8007 and its relay-equipped sibling the Masoneilan 8008 are electro-pneumatic transducers from Baker Hughes that convert a low-power direct-current signal into a proportional pneumatic signal. The output is either 207 to 1035 mbar (3 to 15 psi) or 414 to 2070 mbar (6 to 30 psi), as appropriate to the model, and the instruments are of the force-balance type. They are designed for plants where the controller speaks in milliamps but the final control element works on air.
The distinction between the two models matters at the specification stage. A signal from the Masoneilan 8007 is generally used by a pneumatic positioner or by a supply relay of the volume booster type, whereas the 8008 is fitted with its own relay so that the output can control a pneumatic valve actuator directly. Seven Star LLC is a trusted supplier for Masoneilan and supplies both versions to customers in Oman and the wider GCC, and our instrumentation team checks the signal range, action and approval code before quoting.
Operating Principle of the Masoneilan 8007
In the Masoneilan 8007, any change in the control input signal flowing through the coil changes the gap between a flapper and a nozzle. That alters the nozzle back pressure, which acts against the movement of the beam until equilibrium is restored. In the Masoneilan 8007 the output pressure is simply the pressure of the nozzle circuit, so the instrument acts as a pure signal converter with very low air consumption.
The 8008 adds a diaphragm relay between the nozzle circuit and the output. Supply air enters through a metering tube, and when the flapper blocks the nozzle the pressure in the nozzle circuit rises and moves the diaphragm unit toward the relay plug. That movement closes the vent to atmosphere and opens the supply orifice toward the output. A small bleed between supply and output keeps the plug slightly off its seat to speed up response, and a manual plunger can clear the orifice if necessary.
With direct action, any increase in the input signal increases the output air pressure. With reverse action it decreases it. The action is changed by reversing the connections of the signal leads on the terminal board, so no parts have to be exchanged.
Engineering Design of the Masoneilan 8007
The beam of the Masoneilan 8007 rests on a friction-free fulcrum formed by two beryllium copper flexure bearings. The nozzle has been designed so that vibration has little or no effect on transducer response, and this vibration tolerance is the feature Baker Hughes highlights in the series title. The coil windings are epoxy resin impregnated, and the input circuit can be adapted to DC current signals from most electrical controllers. Signal leads enter through a 1/2 inch NPT hole that accepts a cable gland complying with the relevant protection standard.
The pneumatic supply and output connections are tapped 1/4 inch NPT and sit on the manifold of the 8007 or on the relay of the 8008. Either can be fitted in any of four positions to simplify piping. Several mounting plates allow the transducer to be fitted to the yoke of Masoneilan actuators, and the transducer can be installed in several orientations without affecting its operation.
Key Features
The following points summarise what the Masoneilan 8007 series offers a maintenance or instrument engineer:
- Force-balance construction converts a DC current signal into a linear 3-15 psi or 6-30 psi air signal.
- The Masoneilan 8007 has no relay and is intended to feed a positioner or a volume booster supply relay.
- The Masoneilan 8008 has an integrated relay that lets the transducer drive a valve actuator directly.
- Direct or reverse action is selected simply by reversing the signal lead connections on the terminal board.
- A nozzle design that reduces the effects of vibration helps keep the output stable where the instrument is exposed to vibration.
- Manifold or relay can be turned to any of four positions to suit the piping layout.
- Low temperature versions are offered for operation down to -55 degC, and the 8008 then uses a silicon cloth-reinforced membrane.
- Series numbering covers weather-proof, flameproof and intrinsically safe versions, with ATEX and IECEx approvals.
Industrial Applications
A transducer of this type is the link between an electronic control system and pneumatic hardware. In oil and gas facilities, power stations and desalination plants the Masoneilan 8007 converts the output of a DCS or loop controller into the air signal that a pneumatic positioner expects, and the 8008 can stroke a diaphragm actuator without any additional positioner. Typical cases are retrofit projects where the controllers have been modernised but the field actuators remain pneumatic, as in many established plants around Sohar and Salalah.
In Oman and the GCC, Seven Star LLC supplies the Masoneilan 8007 together with the Masoneilan Type 87/88 actuators it mounts on and the Masoneilan BR200 booster relay that can amplify its signal. Installations that want a different electro-pneumatic converter can review the Masoneilan SVI3 digital valve positioner, and we will recommend the right instrument for the loop.
Technical Specifications
The table summarises the Baker Hughes data for the Masoneilan 8007 and 8008. Performance of a complete system depends on the valve, packing, actuator, transducer and fittings together.
| Parameter | Specification |
|---|---|
| Model | Masoneilan 8007 (without relay) and 8008 (with integrated relay) |
| Input signal | DC current; 216 ohm at 4-20 mA, 2753 ohm at 1-5 mA, 105 ohm at 10-50 mA |
| Output signal | 207 to 1035 mbar (3 to 15 psi); 8008 also 414 to 2068 mbar (6 to 30 psi) |
| Supply pressure | 1586 mbar (23 psi) for both models; 2413 mbar (35 psi) for 6-30 psi on the 8008 |
| Maximum steady-state consumption | 0.30 st.m3/h (8007); 0.45 st.m3/h (8008, 3-15 psi); 0.60 st.m3/h (8008, 6-30 psi) |
| Maximum instantaneous flow | 0.30 st.m3/h (8007); 4.30 st.m3/h (8008, 3-15 psi); 9.00 st.m3/h (8008, 6-30 psi) |
| Hysteresis | 0.8 percent of output span |
| Sensitivity | 0.5 percent of input span |
| Accuracy | Plus or minus 1 percent of full span |
| Supply pressure effect | 0.75 percent of output span per 100 mbar variation at 1586 mbar supply |
| Working temperature | Down to -20 degC; down to -55 degC optional |
| Connections | 1/4 inch NPT air; 1/2 inch NPT electrical |
| Net weight | 3.5 kg (7.7 lb) |
| Numbering | 800a-b: a = 7 without relay, 8 with relay; b = 055 weather-proof, 057 flameproof, 058 intrinsically safe |
Related Masoneilan instruments include the Masoneilan 4411 I/P transducer, Masoneilan BR400 volume booster relay and Masoneilan 4700P/4800P pneumatic positioner.
Request a Quote for Masoneilan 8007
To request pricing or technical support for the Masoneilan 8007 or 8008, send a formal RFQ to the Seven Star LLC instrumentation division with the model code, signal range, output range and area classification. We can confirm the numbering, advise on availability and lead time and provide the Baker Hughes fact sheet from this page. In Oman and the GCC, Seven Star LLC supplies genuine instruments with manufacturer documentation and local engineering support.
- Datasheet Masoneilan 8007/8008 Transducer Fact Sheet 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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