Remote signal transmission and range setting of electromagnetic flowmeters
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The electromagnetic flow meter selected has a pipe diameter of DN50. The range specified in the manual is 0.71~70.65 m3/h, with a remote signal of 4~20 mA. The flow rate of the pump actually used is 30 m3/h. Therefore, how should the range corresponding to the remote signal of 4~20 mA be set on the DCS control side? Should it be set to 0~30 m3/h or 0.71~70.65 m3/h?
First, set the electromagnetic range to 0–35, with an output of 4–20； Set the DCS range to 0–35 again
From a design perspective, it’s not 0~30 m3/h
I think: it should be set between 0 and 70.65 m3/h； Rather than 0.71~70.65 m3/h, and certainly not 0~30 m3/h.
The range of the flow meter should be consistent with that of the DCS; generally, this range is an integer that is greater than or equal to the maximum flow rate.
The last edit to this post was made by qugd on 2010-6-30 at 09:21. The data provided in the manual states that the accurate measurement range for an electromagnetic flowmeter with a DN50 size is 0.71~70.65 m3/h. In other words, its measurement capability can be set by the user or determined at the factory within this range; within this range, the analog signal output can be adjusted as needed, allowing for any setting within the specified limits. Users can choose a suitable value within this range; values such as 0~30, 0~50, 0~18.75, etc., are all acceptable. Modern intelligent electromagnetic flowmeters allow for free setting within their measurable range; the interval between the set values only needs to meet the minimum required interval. When configuring the DCS, the setting for this point can be the same as that of the flow meter. Based on the data, it seems that the poster is using an electromagnetic flowmeter from Yokogawa.
For this issue, you just need to set the range of the electromagnetic flowmeter at the site to match the range set in your DCS; however, the maximum range must not exceed the maximum capacity of the flowmeter itself. It has nothing to do with the flow rate of your pump.