Liquid level detection through the tank wall
The BBDM-1MR2M is an externally mounted ultrasonic transducer for detecting liquid level without placing the sensing element inside the tank. With a 1 MHz center frequency and a reference range of 0.03 to 2 m, it can be evaluated for fuel and oil tanks, sealed vessels, vehicle and machinery tanks, and through-wall detection of corrosive liquids.
An external arrangement can isolate the transducer from the liquid, but the ultrasonic path must pass through the tank wall. Wall material, thickness, surface condition and acoustic coupling are therefore fundamental selection parameters.
Technical specifications
| Parameter | Specification |
|---|---|
| Model | BBDM-1MR2M |
| Center frequency | 1 MHz +/-5% |
| Recommended range | 0.03-2 m |
| Minimum impedance | 60 ohm +/-20% |
| Capacitance | 1,500 pF +/-20% at 1 kHz |
| Operating voltage | Peak voltage below 300 Vpp |
| Operating temperature | -40 to +80 degrees C |
| Pressure rating | Up to 10 kgf or 1 MPa |
| Beam characteristic | -3 dB half-power angle: 3.3 degrees +/-10% |
| Housing material | 2A12 aluminum alloy |
| Protection rating | IP68 |
| Weight | 240 g +/-5% |
| Cable length | 5 m + 1 m |
Coupling and vessel compatibility
The 3.3-degree half-power angle defines a narrow acoustic field, but reliable through-wall transmission also depends on the coupling layer and the vessel construction. Coatings, curvature, welds, deposits or an air gap at the contact face can attenuate the signal.