Boiler Drum Level DP Transmitter Boiler Drum Level DP Transmitter jn12 (Industrial) (OP) 15 Feb 12 12:32 Why is it that they put the low leg of transmitter at the top of the drum, and the high leg of transmitter at the bottom of the drum. RE: Boiler Drum Level DP Transmitter xnuke (Electrical) 18 Feb 12 19:32 The high leg senses the drum pressure plus the weight of the column of water above it; the low leg senses only the drum pressure. xnuke"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips. RE: Boiler Drum Level DP Transmitter Compositepro (Chemical) 18 Feb 12 19:43 The "high" port on the pressure sensor means high pressure, not high elevation. The higher pressure is at the bottom of the drum.