L100 Bubble Tube Liquid Level System

L100 Bubble Tube Liquid Level System

Precision Transmission of Liquid Level in Open Tanks

The L100 Bubble-Tube Level System is a fully self contained instrument (liquid level system), requiring only connections to air or gas supply, dip tube and electrical power source to provide precise level measurment. Because only the stationary dip tube and the purge gas come in contact with the liquid, this system is ideal for applications involving hazardous locations or liquids which are highly corrosive, viscous, hot, (molten metal), explosive, slurry type or foodstuff. Some of the specific applications include waste and water treatment plants for municipalities and trash to energy plants. In addition, the electronic output from the L100 is compatible with almost all analog instrumentation, including local and remotely-located indicators, computers, data loggers, recorders and controllers.



0-50 inches water to 0-115 feet water or equivalent, full scale

Gas Input

1.0 to 7.0 SCFH, regulated on-board to a pressure between 120% or 3 psi, whichever is greater, and 200% of full scale liquid head. Maximum blow-down pressure is 150 psi. Maximum on-board regulated pressure is 60 psi

Electrical Input

Using P200: 10-42 VDC (units with automatic blow-down and digital readout options also require 120 VAC)

Electrical Output

P200: 2 wire, 4-20mA into 700Ω at 24 VDC or 2 wire, 10-50mA into 280Ω at 110 VAC


±0.25% of span guaranteed; ±0.20% of span typical. Includes combined effects of linearity, hysteresis and repeatability errors.


±0.02% of span guaranteed


±0.10% of span max; ±0.05% of span typical

Operating Temperature

30°F to 161°F

Thermal Sensitivity

Span: 0.007% of span per °F guaranteed
Zero: 0.007% of span per °F guaranteed 

RFI/EMI Effect

Meets or exceeds SAMA PMC 33.1, 1978, 2-abc: 0.1% of span at 10 volts/meter


P/I is NEMA 4X and explosion proof, standard. Entire plate assembly fits in an optional NEMA 4X enclosure for further protection.

Available Options

NEMA 4X enclosure with or without digital readout, remote analog readout, auto purge

Ordering Information

The following ordering codes are sufficient to specify a complete bubble-tube system with the exception of the P/I transducer. The P/I transducer must be ordered separately. Please refer to ControlAir's specifications for the Dahl P200 P/I Transducer.


Ordering Code Description
L100 Basic bubble-tube system
L100R Basic system with remote pressure sensing
L100A Basic system with automatic blow-down
L100AR Basic system with remote pressure sensing and automatic blow-down

For a NEMA 4X Enclosure, add suffix E to end of part number. A large enclosure (L100A, L100AR, L100-L22) is needed when ordered with Digital readout.


Ordering Code Description
L11 0-50" WC to 0-166" WC, specify
L12 0-167" WC to 0-498" WC, specify
L13 0-499" WC to 0-830" WC, specify


Ordering Code Description
L22 Digital readout, scaled for range

When ordering, it is necessary to specify the model number, range and all options in the following manner.

For a complete systems (remote sensing in NEMA 4X enclosure with digital readout):
System with
remote sensing
in NEMA 4X enclosure
with digital readout
+ P200 (0-60" w.c.)
For a panel without I/P transducer:
L11 (for a range between 0-50" and 0-166" w.c.)

The P/I transducer must be ordered separately. Please refer to ControlAir’s specifications for the ControlAir P200 P/I Transducer.

When ordering, please indicate the specific gravity of the liquid being measured if it is different from that of water.