Rosemount 1151GP - Page 30

Reference Manual
00809-0100-4360, Rev BA
August 2008
Rosemount 1151
2-20
Bubbler System in Open Vessel
A bubbler system that has a top-mounted pressure transmitter can be used in
open vessels. This system consists of an air supply, pressure regulator,
constant flow meter, pressure transmitter, and a tube that extends down into
the vessel.
Bubble air through the tube at a constant flow rate. The pressure required to
maintain flow equals the liquid’s specific gravity multiplied by the vertical
height of the liquid above the tube opening. Figure 2-11 shows a bubbler
liquid level measurement example.
Figure 2-11. Bubbler Liquid Level
Measurement Example.
mA dc
Let X equal the vertical distance between the minimum and maximum
measurable levels (100 in.).
Let SG equal the specific gravity of the fluid (1.1).
Let h equal the maximum head pressure to be measured in inches of water.
Let Range equal zero to h.
Then h = (X)(SG)
= 100 x 1.1
= 110 inH
2
O
Range = 0 to 110 inH
2
O
20
inH
2
O
0
4
110
T
AIR
X