The benefits of selecting the right cleaning system include:
- Increased milking efficiency: installing a well designed system will ensure efficient operation.
- Reduced costs: installing the right system will keep operating costs to a minimum.
Automation of the cleaning process can be advantageous as it provides consistency of operation, eliminates human error, and prevents health and safety issues associated with handling strong chemicals and hot water.
If the cleaning process is automated the operator needs to periodically check the automation to ensure the plant is cleaning properly.
Machine cleaning requirements
An easy-to-operate method of cleaning the pit and milking platform is essential. Some larger dairies are installing automatic washing systems on their milking platforms. This is especially useful if the dairy is used for long periods of time.
Features of a cleaning system
A cleaning system should have the following features
- Adequately sized and configured wash line.
- Minimum flow rate of 3 litres per minute per cluster.
- Flow rate through the first jetter should not greatly exceed the last.
- A flushing pulsator/air injector may be installed at the end of the milk line to ensure it is cleaned effectively. If the milk line is a loop line then a tap is installed near one of the milk line entries to the receiver with a flushing pulsator/air injector installed before the tap, at the top of the milk line. During washing the tap is closed and the flushing pulsator/air injector turned on.
- Cause minimal liner stretch and distortion.
- A high flow, rapid dump hot water service to save time filling drums.
- Ensure liners and jetters are compatible.
Circulation cleaning sytems
This type of system is recommended for all dairies.
At the completion of milking, the clusters are connected to ‘jetters’ that are in turn connected to a wash line.
When the milking plant is turned on the vacuum created by the plant draws water from the wash tub through the wash line.
When hot washing, the water should be circulated through the plant for 5-7 minutes, or until it reaches the minimum dump temperature (about 55°C). This is done by connecting a recycle line from the delivery line to the wash tub.
To ensure effective cleaning a minimum water flow of 3 L/min is required through each cluster.
To clean the milk line effectively a flushing pulsator/air injector is normally needed. The flushing pulsator injects air and water into the milk line every 30-45 secs. This injection of water and air creates a turbulent flow of wash water through the milk line which helps to effectively clean the milk line.
Advantages and disadvantages of circulation cleaning systems Advantages Disadvantages Safe to operate - especially if chemical dosing is automated. Care should be taken if re-circulating the washing solution as it may become too cold and re-deposition may occur. Good contact time and turbulence in cluster. High initial capital cost. Improved turbulence for large bore milk lines with air injector fitted. Chemical handling/spillage is possible with non automated systems. Easy to re-circulate wash water to increase contact time and effectiveness of detergents. Monitoring is required to ensure that all clusters get water, every wash. Easy to automate. Monitoring to ensure jetter rubberware is not stretched or split - air admission. Advantages and disadvantages of automating circulation cleaning systems Advantages Disadvantages Can eliminate manual handling of chemicals and allow the oeprator to leave the area while the plant is cleaned. Not working correctly and going unnoticed by people until demerti milk occurs. Provide consistent operation regardless of operator, providing they are well maintained. Detergent dispenser not refilled and run empty.
Reverse flow cleaning systems
Reverse flow systems are no longer recommended by the industry for use in New Zealand dairies apart from to rinse the plant with cold water.
In this system, the vacuum pump is switched off and the hose is connected to the milk line between the receiver and the milk pump.
The wash solution is pumped through the hose in to the milk line and passes out through the clusters, flowing in the opposite direction to the normal milk flow.
They have a higher water requirement than other wash systems.
Advantages and disadvantages of reverse flow cleaning systems Advantages Disadvantages Relatively simple to operate. Expensive to establish, with larger hot water requirements and pumps required. Quick to operate, and no time or energy required for attaching jetters. Expensive to run due to high water use and high chemical usage. Quick draining of all milking machine parts. Contact wash time very limited. Difficult to automate. Difficult to perform heavy duty clean if required. Because liners are not pulsating, they may not be cleaned properly. Very inefficient use of hot water. All parts of plant not washed adequately. Unless well installed can be dangerous to operators.
Bucket washing is rarely used now in New Zealand dairies.
In this system the machines are left running and the wash solution is drawn up into the machines via cups from buckets.
The wash solution flows through all of the milk pipes in the same direction as the milk. No special equipment is required except buckets.
This system requires 30 litres of water per cluster per day, and has a high labour component.
Advantages and disadvantages of bucket washing systems Advantages Disadvantages Inexpensive to establish. High labour cost (if done properly). Very effective results if done properly. Danger due to carrying of hot water in buckets. Difficult to circulate detergent should a heavy duty clean be needed.
Bulk milk tank cleaning systems
Automation of bulk milk tank cleaning can enable the tank to be cleaned immediately after emptying, reducing the risk of milk residues setting on the tank surfaces, and therefore limiting the opportunity for bacterial growth.
Different methods of cleaning the bulk milk tank require varying labour inputs and offer varying scope for automation.
Manual cleaning systems
Manual cleaning involves cleaning of the bulk milk tank using buckets and brushes. It is limited to small lidded tanks as good access to all internal surfaces is needed.
- Inexpensive to establish.
- Effective results if done properly.
- High labout cost (if done properly).
- Danger due to lifting buckets of hot water and detergent into tank. Protective clothing should be worn when manually washing bulk tanks.
- Prone to people taking short cuts due to time needed to do the job correctly.
- Areas of the bulk tank are easily missed - under bridge, agitators and corners.
Manual cleaning in place
Manual CIP involves the fitting of a spray ball or similar device into the top of the bulk milk tank. The spray ball distributes cleaning solutions to all of the internal surfaces. Pump sizes, spray ball design and water volumes need to be matched to provide good cleaning.
- Can be retro fitted to most bulk tanks.
- Relatively inexpensive to install.
- Sparay balls can block, resulting in areas of the tank not being cleaned.
- Limited contact time of detergents if the water is not recirculated.
Automatic cleaning in place
- Wash cycles can be tailored to suit size and configuration of tank and local resources.
- Repeatable and consistent wash cycles.
- Error and fault reporting.
- Integrated with cooling systems.
- Usually supplied with a dedicated hot water service.
- Minimal handling of chemicals.
- Required volumes of water and chemicals are reduced by recirculation.
- Tank can be completely washed immediately after emptying.
- Little labour input.
- Wash times can be excessive (outside milk processor requirements) if the water pressure is low.
- Spray balls can block, resulting in areas of the tank not being cleaned.
- Often only available as an integral part of the bulk tank.
- No system is fully automatic - chemical drums and effectiveness of wash program need to be monitored.
- Automated systems not working correctly and going unnoticed by people.
- Power cuts may change cleaning cycle times.
- Check that your machine cleaning routine suits the system.
- Check the milk dockets and if any bacterial alerts/grades show on the docket then complete a full plant/vat inspection.
- Perform a monthly check on your machine cleaning system to make sure it is working correctly.
- Use any spare time while the wash is going through to:
- Check that all of the clusters have water going through them.
- Check the wash line injector or flushing pulsator is working (you should be able to see turbulence in the receiving can).
- Time the recycle time of the alkaline washes on the plant and vat and ensure the washes are being recycled for at least 5mins.
- Check initial hot water wash temps are 80-85°C in the tub and when recycling the wash solution ensure it is dumped before it reaches 55°C.
- Check that the chiller in the milk silo is on and working.
- Hose the dairy and yard areas.
- Update animal health records and transfer any information from whiteboards etc.
- Plan the effluent irrigator runs and update records
- When installing a system consider the costs involved and the labour input required.
- Beware: bulk milk tank cleaning requires the use of concentrated chemicals and/or large volumes of hot water. Health and safety issues arise from this practice. Many tanks are ‘confined spaces’ and entering them can have fatal consequences from asphyxiation. Always remove the silo door when you enter.
- Never stand in a confined space where acid and alkaline cleaners mix e.g. at the bottom of the bulk milk tank.