How to use the Fisher valve positioner

Adjustment of Electric Valve Positioners

Calibration equipment preparation: Standard instrument DRUCK TRX-II industrial process calibration instrument, pressure module, manual low-pressure generating pump; two walkie-talkies; several adjustable wrenches; several Phillips and flathead screwdrivers; sealing tape for pipes.

Calibration personnel preparation: Operator A records real-time data and issues test instructions on the upper computer, Operator B performs on-site debugging, and Operator C makes on-site records.

Calibration steps: Connect the pressure module to the signal connection line of the DRUCK TRX-II. Turn on the power of the DRUCK TRX-II and set it to pressure test measurement mode.

1. Zero Position Adjustment

The purpose of zero position adjustment is to ensure that all components of the positioner are in the correct working position. The process of zero position adjustment is as follows:

⑴ Adjust the stroke of the actuator to the middle position, align the 0 position on the lever with the 0 position mark on the positioner housing, and then make the stroke pin perpendicular to the lever, ensuring that the full stroke value corresponds to the scale on the lever.

Note: When the valve stem stroke is less than 1 to 1/8 inches (29mm), the stroke pin must also be at the 1 to 1/8 mark.

⑵ Loosen the nozzle lock nut, turn the nozzle positioner clockwise to the end, and then turn it counterclockwise for 2 turns to secure it.

⑶ Remove all loads from the positioner and connect the positioner's output to the actuator's input.

⑷ Connect the input signal to the positioner, first input the middle value. For example: for the 3582 series positioner with a signal range of 3 to 15 psig (0.2 to 1.0 bar), input 9 psig (0.6 bar), and then supply air to the positioner.

Note: During normal operation, the baffle must face the nozzle, ensuring that the baffle does not move or twist.

⑸ Adjust the baffle to the zero position on the scale of the push plate, and the output pressure should also be the middle value. If not, loosen the baffle screws and adjust it to achieve the middle value, then tighten it.

⑹ Turn the baffle to the positive action quadrant scale of 10, and the output pressure should also be the middle value. If not, adjust the corrugated pipe bolt to achieve the middle value, then tighten it.

⑺ Turn the baffle to the negative action quadrant scale of 10, and the output pressure should also be the middle value. If not, adjust the push plate bolt to achieve the middle value, then tighten it.

⑸ Repeat to check if the baffle is facing the nozzle. If not, readjust the nozzle and baffle until the zero position is reached. Prepare for stroke adjustment.

2. Stroke Adjustment

⑴ Remove the load and connect the positioner output to the actuator input. Input the signal to the positioner and set it to the middle value.

⑵ Adjust the baffle to approximately the 6 position on the push plate scale (positive action quadrant or negative action quadrant), supply air to the positioner, and the actuator should move to its stroke's middle value. If not, first check if the joints are loose and if the cam is installed correctly. If the push plate is uneven, slight adjustments to the nozzle height can align the expected input signal value with the stroke starting point.

⑶ Input the lowest signal value to the positioner. For example, for the 3582 series positioner with a signal range of 3 to 15 psig (0.2 to 1.0 bar), input 3 psig (0.2 bar). Loosen the nozzle lock nut, adjust the nozzle until the actuator moves to its stroke's lowest point. Changing the position of the nozzle also changes the zero position reference point.

⑷ Input the highest signal value to the positioner. If the actuator stroke is less than the required stroke range, move the baffle to a slightly larger position on the push plate scale, and the actuator stroke will increase accordingly. Conversely, if the actuator reaches its stroke value before the output signal reaches the highest value, move the baffle to a slightly smaller position on the scale.

⑸ Repeat until the desired stroke value is reached. Each time the baffle position is changed, repeat ⑶ to provide the correct starting position.