0
TECHNICAL BRIEFS

A Method for Liquid Level Detection Under Complicated Boundary Conditions

[+] Author and Article Information
Frank May

Swiss Federal Institute of Technology Zurich (ETHZ), Institute of Mechanical Systems-Mechanics, CH-8092 Zurich, Switzerlandfrank@kosta.ch

Jürg Dual

Swiss Federal Institute of Technology Zurich (ETHZ), Institute of Mechanical Systems-Mechanics, CH-8092 Zurich, Switzerlandjuerg.dual@imes.mavt.ethz.ch

J. Vib. Acoust 128(4), 535-539 (Feb 27, 2006) (5 pages) doi:10.1115/1.2203240 History: Received November 12, 2004; Revised February 27, 2006

In this paper a method of liquid level detection by mechanical resonant vibrations is presented which is based on longitudinal vibrations of a steel capillary and is able to detect a liquid surface even if covered with foam, as well as if the fluid container is shut by a cap. The behavior of the vibrating system is calculated by a simple model and compared with experimental results.

Copyright © 2006 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Sketch of the aluminum clamping of the steel capillary

Grahic Jump Location
Figure 2

Model for the free vibrations of the capillary

Grahic Jump Location
Figure 3

Model for the vibrations of the capillary in contact with fluid

Grahic Jump Location
Figure 4

Model for the vibrations of the capillary in contact with the cap of a container

Grahic Jump Location
Figure 5

Experimental setup for measuring the resonant characteristics and the behavior for level detection

Grahic Jump Location
Figure 6

Influence of fluid contact on the resonant characteristics. Comparison of modeling and experiments for the fifth mode of longitudinal vibration (94.9kHz).

Grahic Jump Location
Figure 7

Behavior of amplitude and phase for the fifth mode of longitudinal vibration (94.9kHz) while the fluid surface moves relative to the pipetting needle in steps of 0.1mm

Grahic Jump Location
Figure 8

Time history of amplitude and phase for automatic LLD with the fifth mode of longitudinal vibration (94.9kHz)

Grahic Jump Location
Figure 9

Verification of the automatic LLD with a CCD camera. Left: before contact; right: just after contact to fluid surface.

Grahic Jump Location
Figure 10

Comparison of the measured resonant characteristics for free vibrations, in contact to foam and after the transition to fluid. Fourth mode of longitudinal vibration (69.2kHz).

Grahic Jump Location
Figure 11

Evaluation of phase jumps without (left) and with (right) gliding mean value (n=5) for automatic LLD of foam covered fluid surface. Fourth mode of longitudinal vibration (69.2kHz).

Grahic Jump Location
Figure 12

A foam bubble sticks on the abutting face of the needle and moves into the fluid

Grahic Jump Location
Figure 13

Influence of a cap on the resonant characteristics for different positions. Comparison of experimental results and results from modeling for the fifth mode of longitudinal vibration (94.9kHz). Distance needle tip to cap: position 1=0mm; position 2=0.5mm; position 3=1mm; position 4=1.5mm; position 5=3mm; position 6=4mm.

Grahic Jump Location
Figure 14

Time history of amplitude and phase while detecting with caps on the fluid container for the third mode of longitudinal vibration (44.7kHz): (A) without contact, (B) needle tip in contact with cap, (C) needle tip passed cap, (D) needle in contact to fluid (E) driving back of needle

Grahic Jump Location
Figure 15

Definition of a detection window for an automatic LLD when containers with caps are used. Fifth mode of longitudinal vibration (94.9kHz).

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In