[Q&A Question 124] 2016.08.22

I. Installation Precautions 　　1. The gas flow transmitter should be installed in a location that is easy to maintain, free from strong electromagnetic interference, severe mechanical vibrations, and thermal radiation effects； 　　2. Flowmeters should not be used in situations where flow is frequently interrupted, or where there are strong pulsations in the flow or pressure ； 　　3. When a gas flow transmitter is installed outdoors, it should be covered at the top to prevent rainwater from seeping in and direct sunlight from affecting its service life. The transmitter can be installed at any angle, provided that the flow direction of the fluid is consistent with the direction indicated on the transmitter ； 　　4. During pipeline construction, it is necessary to consider installing expansion joints or bellows to prevent severe stretching or breaking of the flow meter ； 　　5. The gas flow transmitter should be installed coaxially with the pipeline, and measures should be taken to prevent seals and grease from entering the interior of the pipeline ； 　　6. When an external power source is used, the flow meter must have a reliable grounding; it shall not share a ground wire with high-voltage electrical systems. During pipeline installation or maintenance, the ground wire of the welding system shall not be connected to the flow meter. 　　7. To avoid interfering with the normal flow of the fluid and to facilitate maintenance, bypass pipes should be installed, ensuring that there are straight pipe sections of at least 3DN in front and at least 1DN behind ； For 2D

Close the inlet and outlet valves, perform nitrogen purging, and contact the instrumentation team for handling

Contact the process personnel to disable the process interlocks and equipment interlocks, close the valves at the base of the pressure tapping pipes (at least two), and replace them

Disconnect the associated interlocks, close both the positive and negative pressure tapping valves, drain the gauge, replace the transmitter; once the new transmitter is functioning properly, re-enable the interlocks.

Steps: Disconnect the associated interlocks, close the double valves for the positive and negative pressure lines, drain the gauge, replace the transmitter; once the new transmitter is functioning properly, re-enable the interlocks.

Set the flow rate to manual control, close the primary hand valve of the transmitter, remove the transmitter and replace it, open the primary hand valve, check for leaks, and once the flow rate is stable switch to automatic mode

Activate the shutdown interlock for cut-off flow to maintain stable inlet pressure and outlet temperature; close the valve at the root of the flow meter, and coordinate with the instrumentation team!

1. Remove the transmitter 2. Release pressure at the drain port 3. Replace it

The hydrogen underreporting interlock must be removed first before the instrument can be replaced