Becker Digital Natural Gas Positioner Instruction Manual | 13
© 2022 Baker Hughes Company. All rights reserved.
2. Introduction
The DNGP is designed specifically for the needs of the natural gas industry. By using solenoids to control
the actuator pressures, the DNGP eliminates the continuous bleed gas produced by I/P transducers and
bleeds no gas until the valve is called upon to move. The DNGP can even do this while maintaining a
pressure difference across the actuator. Additionally, the discharge can be directed downstream, and the
positioner can fail in last position on a loss of signal, DC power or power gas. Reliability and simplicity have
been engineered into the DNGP, while features that make the positioner versatile, easy to use, and fail
safe, have been retained.
Note: In order to reset fuses, F1 and F2 are resettable by cycling the boards on and off.
Principle of Operation
The solenoid operated electro-pneumatic positioner compares a 4-20 mA signal from a Remote
Transmitting Unit (RTU) to a 4-20 mA signal from a position transmitter. Depending upon the difference
between the two signals, the positioner energizes the open or close solenoid to drive the control valve
toward the desired position. If the signals are within an adjustable dead band, neither solenoid is
energized. The solenoid tubing is connected to the valve actuator through a variable orifice. This orifice
allows the valve speed to be increased or decreased. The faster the valve speed, the larger the positioner
dead band must be to prevent overshoot of the valve position. When the input signal falls within operational
deadband of either full open or full closed, and bypass enable is selected, the positioner continually
energizes the appropriate solenoid to provide a full pressure differential across the cylinder.
Scope of Manual
This manual provides information on the installation, adjustment, and maintenance of the DNGP-Digital
Natural Gas Positioner. For information concerning actuators, valves, and accessories, refer to the
instruction manuals provided with the specific product.
Technical Assistance
Only those qualified through training or experience should install, operate, or maintain Becker positioners.
If you have any questions concerning these instructions, contact your local Baker Hughes sales
representative, sales office, or manufacturer before proceeding.
Offices are listed on the back cover.
