Masoneilan models 4700E/4800E (electropneumatic) and 4700P/4800P (pneumatic) are field-proven positioners from GE Oil & Gas that use a precision feedback cam to provide accurate positioning, fast response, and customized control characteristics for control valves. These positioners can be used with either rotary or reciprocating actuators. On rotary actuators, the cam is mounted directly on the shaft. When mounted on reciprocating actuators, a simple, rugged turnbuckle and lever assembly couples stem motion to the cam.
The main features of the models 4700P/4700E and 4800P/4800E positioners are:
One Multi-lobe Cam The cam provides field-changeable linear, split-range linear and equal percentage control characteristics. Custom characteristics are available on special order.
Zero Adjustment Adjustment of the positioner zero can easily be accomplished by means of the adjustable spring button. Further zeroing can be performed through the turnbuckle assembly on linear motion actuators.
Corrosion-resistant Materials Premium performance is the standard on the models 4700P/4700E and 4800P/4800E positioners. Internal components are manufactured of corrosion-resistant materials for protection against the harshest environments.
Fully Enclosed All adjustments are fully enclosed for protection from the environment.
Simplicity Positioner action can be reversed without additional parts (4700P/4800P only). The same mounting orientation is used for both direct and reverse action.
Easy to Maintain The pilot valve is the only moving part in the pilot housing. It is easily removed without disassembling any other part of the positioner. An optional bypass valve module is available for use on the model 4700P pneumatic direct acting positioner. Where operating parameters allow, it permits the positioner to be isolated for maintenance while operating the valve directly with the instrument signal. The bypass module is mounted on the back of the positioner to discourage tampering.
Optional Bypass A molded nylon bypass valve with an O-ring seal permits continued automatic control during the cleaning of the pilot valve. The bypass valve is concealed in back of the unit to prevent tampering. The bypass is available only on the direct action 4700P pneumatic positioner.
Damping Adjustment On model 4700, actuator travel speed can be adjusted as required for stable operation