why is negative range given to measure the steam drum level

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why is negative range given to measure the steam drum level..

Answer / sreekanth

Because of the wetleg compensation. In the drum the high
pressure is at the lower tap and Low pressure is at the
Upper tap. The wetleg is connected to the Upper Tap and the
DP across the taps will be -ve if there is no drum level.
so the range of the transmitter will be -XXX to 0 mmwc.

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why is negative range given to measure the steam drum level..

Answer / ranjan

but in drum, pressure is equal in all area

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3 Yes

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