Dynamic characteristics of vacuum milking systems were studied by exciting an experimental system with a multiple-frequency binary sequence of air admission and analyzing the vacuum responses in the frequency domain. The system normally behaved as a low-pass filter to air admission disturbances, but slugging in milklines was found to propagate high-frequency vacuum fluctuations in the wetted part of the system.

Frequency Characteristics and Propagation of Vacuum Fluctuations in Milking Systems

14 Cleaning and Sanitation

Emploi d'un flux gaz/liquide en utilisant la depression realisable a l'aide d'installation de traite a vide . Dans des conditions definies, le flux gaz/liquide forme des slugs qui passent rapidement a travers le pipeline. Ces slugs possedent une energie cinetique considerable, qui est concentree sur des sections relativement petites du systeme de flux. Cette energie excedentairepourrait etre utilisee au cours du nettoyage comme composant mecanique sous forme de pertes par friction de la paroi

56. Zur Reinigung der Milchsammelleitung mit Hilfe einer 2-Phasen-Strömung

Equations were developed to predict milkline fill and the transition from stratified to slug flow under normal milking conditions. The equation to predict fill explained 93% of the variation in the experimental data for 48 to 98 mm milklines sloped at 0.5 to 2%. The prediction equation for the transition from stratified to slug flow accounted for 98% of the variation in the experimentally determined transition points.

Prediction of milkline fill and transition from stratified to slug flow

The results of an experimental study of two-phase flow characteristics in dual-purpose milklines under milking conditions is presented. This project was undertaken to provide data for the revision of United States and international standards for sizing milklines in milking machine installations. The experimental setup and conditions are described. The key performance indicator of stratified flow is that vacuum in the milkline should not fall more than 2 kPa below the receiver vacuum during milking. Design criteria to meet this performance guideline should include milkline diameter and slope as well as expected peak milk flow, and steady and transient air flow rate per slope.

D. J. Reinemann

Papers

Transition from Stratified to Slug Flow in Milklines