The centre point of the new dairy is of course the bulk tank. This is a
7,000 litre every other day (can only cool half of its total capacity in a day)
ice bank tank. It had two agitators and an automatic wash system. We chose an
ice bank tank as this can make good use of night time electricity which is one
third of the price of daytime electricity. This greatly reduces the cooling
cost per litre. We also choose a tank that would hold two days milk all year
round as this reduces transport charges.
When the milk comes through to the dairy from the receiver jar in the
parlour it first passes through twin mesh filters. It then gets cooled in a two
stage plate cooler. This is basically a heat exchanger. In the first stage the
milk is cooled using water from the farms bore hole. This will cool the milk
from body temperature (approx. 35 °C) to about 14 °C. The second
stage of the plate cooler chills the milk still further using chilled water from
the ice bank of the bulk tank which cools the milk down to about 4 - 5 °C.
The washing system is very straight forward. After morning milkings boiling water and acid are used to clean the plant. This goes straight through and there is no need for re-circulation. After evening milking cold water and hypochlorite are used to clean the plant. The wash manifold ensures that the proper amount of chemical is added.
The main philosophy behind the design of our new dairy was to keep the area as clean as possible considering it is a food storage area. The walls and floors are plastered with terraza. The ceiling has been covered with plastic tongue and groove sheeting. There is no direct entrance from the parlour to the dairy in an effort to keep it cleaner. There is a window between the parlour and the dairy so the milker can check the swinging arm is in the right position for milking / washing. The unit is designed that people can exit and enter it without going through the dairy which has a separate entrance. The only other equipment in the dairy apart from those which I have already described is a sink for the stockmen / tanker driver to wash their hands and a hose for keeping the place clean.
The plant room is situated next door to the dairy. It contains two condensers which cool the bulk tank. These are situated in front of a grill. It is important that the grill be twice as large as the size of the actual condensers as the air as to flow out as well as in. if the air is trapped the the condensers become less efficient.
In addition to the condensers the plant room also houses two water heaters. One of which comes on only during the hours of cheap night time electricity to provide boiling water for cleaning the plant and the other which is a pressurised water heater and is on all the time to provide water for washing down the bulk tank, hand basins and shower. It is important to always have hot water available for calvings.
The plant room also houses a compressor which powers the automatic cutter gate and the transformers for the parlours electrical equipment.
This rather large three phase vacuum pump which powers the milking parlour
has its home underneath the stairs that go up to the viewing gallery. This
means we can cut down the noise. It is also a good idea to keep the exhaust of
the vacuum pump away from the intake for the bulk tank condoners. This tiny "glory
hole" also houses the teat dip dispenser.
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Page created 2nd November
1997