
Understanding VaDia Viewer data v1.0 4/12 www.biocontrol.no/vadia
3. DEFINITIONS AND BACKGROUND THEORY
Teat-end vacuum fluctuations3.1. Teat-end vacuum stability and pulsation setting are of major influence on the udder health.
All components in the milking equipment (liner, milk tube, cluster, milk line, vacuum regulator,
sanitary trap, etc.) have a dynamic vacuum behavior; the teat-end vacuum therefore is not
equal to the system vacuum.
Clusters are connected to the same milk line and their behavior (attachment, kick-off, etc.)
influences the vacuum in the milk line and therefore in other clusters on that line.
Teat-end vacuum variations can be categorized in three groups:
•Slow vacuum variations:
Teat-end vacuum slowly differentiates from the machine vacuum. This is typically the
result of ‘transport resistance’, i.e. a milk flow dependent vacuum drop between teatcup,
cluster and the milkline. This can be caused by e.g. flow meters, vacuum shut-off valves,
narrow tubes, not enough slope, poor reserve capacity and air leaks.
•Cyclic vacuum variations
Caused by opening and closing of the liner. Typical norm (ISO 5707 and 6690):
- alternate pulsation: ± 5 kPa
- simultaneous pulsation: ± 10 kPa
Note that the norm indicates that simultaneous pulsation (a.o. DairyMaster) gives more
cyclic vacuum fluctuations. This is because all 4 teats get vacuum at the same time which
has an effect on the cluster vacuum. In case of simultaneous pulsation VaDia Viewer
assessment therefore may indicate too many irregular vacuum fluctuations. This can also
happen in case of some automatic milking systems (robots).
•Irregular vacuum fluctuations
This is caused by unintended sudden air inlet, e.g liner slips in the cluster under-test or
attachment, removal or fall-off of other clusters. Putting a bucket to the milkline,
overloading of the milkline and shortcoming of vacuum regulation can also result in
irregular fluctuations.
Short Pulsation Tube (SPT)
Long Pulsation Tube (LPT)