Source: BC Milk Marketing Board
At the request of the BC Milk Marketing Board, the BC Ministry of Agriculture has provided us with the following information on proper plate cooler use & maintenance. Many producers use plate coolers to assist in proper milk cooling and save on energy costs. They can be important in meeting milk temperature requirements and maintaining milk quality, especially when used in conjunction with robotic milking systems which utilize buffer tanks that do not have cooling capabilities.
However, plate coolers are often overlooked when it comes to equipment maintenance. As with all equipment, producers are responsible for routine maintenance of plate coolers to ensure they are working efficiently and effectively. Gasket deterioration is a main concern for plate coolers as black particles can contaminate a farm’s milk supply and deem the milk unsaleable.
In systems using a plate cooler, there should be a milk filter installed during both the wash cycles and milking sessions. The milk filter is installed during the wash to protect the plate cooler from particles entering and potentially creating a blockage and source of bacteria.
The necessary plate cooler maintenance and inspection schedule depends on a variety of factors including, but not limited to, the frequency and duration of use, chemical volumes used during the wash, and pH/mineral content of the water used to cool the milk. It is recommended that producers discuss their operation’s utilization of the plate cooler with the manufacturer to help determine a suitable inspection and maintenance schedule.
A plate cooler’s lifespan can be 20+ years if maintained correctly. Monitoring performance and milk quality are the best things you can do to determine when the plate cooler should be disassembled and fully inspected for problems. The following are some performance checks that can be done to determine if a plate cooler is running efficiently, or may need maintenance:
Temperature of the milk entering the bulk tank
- The temperature of cooled milk should be within 2‐30C of the incoming water. A simple way to monitor this is to use PVC strip thermometers, applied to both the water inlet pipe and milk outlet pipe attached to your plate cooler. Check the two temperatures during peak milk flow from the pump; more than a 30C difference indicates room for improved performance.
Water/milk flow rate
- In the above situation, consider checking the water and milk flow rates; typically ‘M‐series’ plate coolers work most efficiently using a water: milk flow rate of 3:1, while 2:1 is adequate for newer industrial models. Refer to the manufacturer’s recommendations to determine the best ratio based on the specific size and design of the plate cooler.
Plate cleanliness
- Contaminants from either the water or milk can adhere to the plates and affect their heat exchange capacity, thus reducing performance. If the milk flow rate is determined to be adequate and the unit is still inefficient, it may need to be opened and checked for plate fouling. Clean plates by manually applying a cleaning agent and rinsing it off with a soft‐bristle brush and high‐pressure washer, with care taken to not loosen or dislodge the gaskets. Plate fouling is the most common issue with plate coolers.
Leak detection and elimination
- Generally, if leakages occur, they will be observed as a puddle on the exterior of the unit likely due to damaged or worn out gaskets. The unit should be opened up and gaskets individually inspected for damage and wear. Remove gaskets with signs of damage or wear and replace with new gaskets.
- Monitor cryoscope results for added water in the milk supply. Increased water content could indicate differential leaks caused by corrosion or pinholes occurring in the plates. It may also less frequently be caused by gasket deterioration. Unit should be opened up and all plates and gaskets inspected and replaced as necessary.
Correct sizing and spacing of plates
- The number and size of plates in the plate cooler should be matched to the maximum flow rate of the milk pumps.
- If the gap between plates is too small, flow will be impeded and compromise performance. Generally, 2‐3mm should be allowed between plates; refer to manufacturer’s recommendations for further details.
Remember, the more efficient the pre‐cooling system, the greater the savings in electricity consumption and refrigeration operating costs. It is well worth the effort to ensure plate coolers are properly maintained!
If producers have further questions on your plate cooler maintenance, you are encouraged to discuss with your equipment dealers or the Ministry of Agriculture dairy inspectors (Roger or Tamara). Thank you to Tamara Pottrick, BC Ministry of Agriculture Dairy Inspector for providing the above notice and technical details.
Roger Pannett
Cell/Text: 604 819 6420
Email: Pannett@gov.bc.ca
Tamara Pottrick
Cell/Text: 604 226 1405
Email: Tamara.Pottrick@gov.bc.ca
