Farm advice: New milk cooling regulations
The new milk cooling regulations under the Ministry for Primary Industries NZCP1 come into effect for established dairy farms from 1 June
Some of you will already be compliant with the new regulations but others may need to assess their system to see if changes need to be made. The new regulations require milk to be chilled to:
- 6°C within six hours of starting milking; or
- 6°C within two hours of completion of milking; and must be held at 6°C or below until collection or the next milking; and must not exceed 10°C during subsequent milkings.
Monitoring of these new regulations will require that these temperatures are proven:
- at the end of calving, once the full herd is milking
- during peak milk flow in November; and
- during February.
If you haven’t checked your milk cooling system yet, I’d recommend testing it to see if it meets the new criteria before investing in an unnecessary upgrade. A good place to start is to monitor the temperature of your vat over multiple milkings to see if it meets the new requirements.
If the milk temperature doesn’t meet the new regulations, I would first check the performance of your plate heat exchanger (PHE), also known as a plate cooler. There are a number of ways to check if it’s performing efficiently. You could approach a rural professional or do it yourself.
Checking the plate cooler
I find that the easiest way to check the plate cooler is to compare the temperature difference between the incoming temperature of the cooling water and the outgoing temperature of the milk leaving.
A PVC strip thermometer is an easy way to self-check. The thermometers have a paper backing, which is peeled off and stuck directly onto a clean, dry metal pipe.
The temperature difference needs to be under 3°C to ensure your PHE is working efficiently. If the temperature exchange isn’t under 3°C, make sure you have sufficient water flow and the PHE size is sufficient for your herd size.
Optimum water flow for the PHE is around three litres of water to every litre of milk. To check this, hook up a flow meter to see how much water is going through the PHE and compare it to the peak flow of milk from your milk lift pump.
Water entering your PHE also needs to be as cold as possible. Investigate taking it straight from your bore rather than storing in tanks. Don’t recycle PHE water unless it’s chilled between uses.
Wrap your vat
One of the most cost-effective ways to make your cooling system more efficient is to install a vat wrap if it’s single skinned, which can save around 15–25% of the energy required for milk cooling.
If you do need to make changes to your system, don’t leave it to the last minute, as the pressure on rural professionals or suppliers may get higher the closer we get to the regulation date. Also, do your homework. Get multiple quotes to make sure you’re getting the best outcome for your cooling system.
For more information on milk cooling, visit dairynz.co.nz.
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