Six months. 182 days. Seasons change. Holidays happen. You might exchange shorts for insulated coveralls and endure daylight saving time. A lot happens in six months.

And every six months, a specialist should review your milk cooling system. Regular check-ups can prevent equipment failures and help evaluate efficiency to make the most of your milk.

Delicious and nutritious at 37ºF

Milk is perishable. After leaving the cow at 101.5ºF, milk must quickly cool to 37ºF for storage and safe human consumption. Needless to say, your milk cooling system is important.

The milk cooling system acts as a refrigerator, using a compressor to pump refrigerant through it. Within the tank or plate heat exchanger, the refrigerant absorbs heat from the milk. Absorbed heat is then exhausted through the air-cooled condenser of the refrigeration unit.

It might seem simple, but multiple parts need to be in ideal working condition for positive results. When using a bulk cooling tank, milk temperature should lower to 37ºF within the first hour after milking. Subsequent milkings will add warm milk to the already-cooled milk in the tank.


These blended temperatures should not exceed 45ºF. Larger dairies cooling high volumes of milk often use an instant cooling system, consisting of plate coolers and chillers. This equipment helps quickly decrease the temperature of the milk to 37ºF before entering storage.

If a cooling system does not meet these temperature parameters, the system may need maintenance and repair or it no longer meets the cooling demands of your farm.

Factors influencing milk cooling system function

The quantity of milk your dairy produces per hour determines the amount of refrigeration your cooling system needs. It’s not the number of cows but the size of your milking facility that affects your cooling system.

If you plan to grow your dairy and produce more milk, a standard milk tank may not work. Rather, a chiller system will accommodate a production increase by instantly cooling milk in the plate heat exchanger with well water and chilled glycol solution. From the exchanger, the milk leaves at 36ºF. The milk will then be stored in a milk tank or sent directly to a milk tanker.

Climate also impacts your milk refrigeration system. Your specialist will look at the condenser and determine if the size is appropriate to maintain efficiency during high-ambient temperature situations. Cooler temperatures help maintain efficiency of the milk cooling system. However, when a refrigeration unit is housed outside, extremely cold temperatures can prevent it from starting.

Extremely hot temperatures can also affect the system; starting at 90ºF, you can expect a 10 percent decrease in capacity capabilities for every 10ºF increase of external temperatures. For example, at 100ºF, capacity capabilities would decrease by 20 percent.

Preventing milk cooling system issues

Just like taking care of yourself and your animals, you should also care for your equipment. Whether it’s a change in weather, an increase in production or general wear and tear of parts, stay alert to adjustments and maintenance needed to keep your cooling system working properly.

  • Air flow: Proper air flow helps the milk cooling system work efficiently. Most utility rooms don’t have exhaust fans to remove hot air. It’s also common for the condensing unit to be placed in corners of utility rooms – a popular area for miscellaneous farm items to pile up, restricting the movement of air.

    Avoid setting items around your milk cooling condensing unit to prevent air flow issues. If the area around the compressor gets closed for the winter, ensure it is opened when the seasons change. Also make sure your system’s fan is clean.

  • Refrigerant: The amount of refrigerant in your system, dirty coils or low refrigerant pressures affect the productivity of your milk cooling system. Your site glass should be clear and contain no bubbles. If you’re noticing bubbles or an issue with the rate of cooling, ask your specialist to look at your milk cooling system to avoid extra expenditure of energy.

  • Temperature and time: The higher the temperature of your milk, the more likely bacteria will grow. Your system’s temperature recorder will track your milk’s temperature at the end of each milking and the length of time it takes to reach storage temperature.

    If your temperatures are exceeding 45ºF after the milk is blended or your cooling system is running longer than 30 minutes after the end of each milking, immediately contact your dealer’s milk cooling specialist.

  • Employees: Educate your employees about the importance of keeping milk cool. Teach them how to track temperature, time and what issues to look for. Encourage them to inform you or have them contact your dealer when a problem occurs.

  • Scheduled maintenance: A maintenance check-up with your milk cooling specialist involves cleaning condensers, checking fan motor operations, charging refrigerant and completing amp draws for all motors. Work with your dealer’s milk cooling specialist to schedule an appointment every six months.

Your milk cooling system has a big job to help prevent growth of bacteria and maintain a high-quality product. A cooling system check by a specialist every six months can eliminate after-hour service calls. Be aware of possible issues and indicators between your appointments to prevent complications from worsening and, in some cases, having to dump your milk.

You are not expected to be a milk cooling expert, but your cooling specialist is. Contact your dealer to ensure your milk cooling system is helping you produce the highest-quality milk possible.  end mark

PHOTO: A cooling system check by a specialist every six months can eliminate after-hour service calls. Photo courtesy of GEA.

Kevin Kastenschmidt