Masoneilan 4700/4800 E (electropneumatic) and 4700/4800 P (pneumatic) (pneumatic) are reliable positioners developed by Baker Hughes, designed to deliver precise positioning, rapid response, and tailored control characteristics for control valves through the use of a precision feedback cam. These positioners are compatible with both rotary and reciprocating actuators. In the case of rotary actuators, the cam is directly affixed to the shaft, while for reciprocating actuators, a robust turnbuckle and lever assembly connects the stem motion to the cam.
The key features of the Masoneilan 4700/4800 positioners include:
This cam allows for field-changeable control characteristics, including linear, split-range linear, and equal percentage options. Custom characteristics can be ordered upon request.
The zero setting of the positioner can be easily adjusted using the adjustable spring button. Additional zeroing can be achieved through the turnbuckle assembly on linear motion actuators.
The Masoneilan 4700/4800 positioners are built for premium performance, with internal components made from corrosion-resistant materials to withstand the most challenging environments.
All adjustment mechanisms are fully enclosed to safeguard them from environmental factors.
The action of the positioner can be reversed without the need for extra components (applicable to 4700P/4800P only). Both direct and reverse actions utilize the same mounting orientation.
The pilot valve is the sole moving part within the pilot housing and can be easily removed without disassembling other components of the positioner. An optional bypass valve module is available for the 4700P pneumatic direct acting positioner, allowing for maintenance isolation while the valve continues to operate directly with the instrument signal. This bypass module is mounted on the rear of the positioner to prevent unauthorized access.
The bypass valve, constructed from molded nylon and featuring an O-ring seal, allows for uninterrupted automatic control while the pilot valve undergoes cleaning. This bypass valve is strategically located at the rear of the unit to deter any unauthorized access. It is exclusively available on the direct action 4700P pneumatic positioner.
Damping Adjustment For the 4700 model, the speed of actuator travel can be modified as needed to ensure stable performance.
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