24 July 2023
Maximising the effective operation of automatic washers for milking equipment
Automatic washers were conceived and installed to reduce labour requirements and save time on farms, which they undoubtedly do. Like any machine, they require regular monitoring and calibration to ensure that they are working correctly.
David Gleeson and Lorna Twomey tell us more on monitoring the operation of your automatic washer and milking plant below.
Detergent usage
1). To know how much detergent or acid is required at each wash occasion it is necessary to establish how much water is used for both rinsing and washing the machine. This can be deduced via the following formula:
- Length (cm) x Width (cm) x Height (cm) (height = the water mark);
- Where the width of the trough is tapered, measure the widths at both the top and bottom of the trough – get the average width and use this in your calculations;
- Divide the answer (that you get from the above formula) by 1,000 to convert to litres. Divide the volume by the number of milking units that you have to determine the volume available per unit. The target volume per unit is 14L/unit for rinsing and 9L/unit for washing.
- A wash trough calculator is also available on the Teagasc milk quality webpage
2). Ascertain the recommended usage rates of the chemicals that you are using by reading the label on the drum. Please note that most chemicals will have a different usage rate for hot and cold washes, as a greater chemical volume is needed for cold washing (to compensate for the lower temperature).
3). Calculate how much detergent your machine requires by multiplying the volume of water used for washing by the usage rate declared on the product label. For example:
- Hot wash rate: 200 litres x 0.7% = 1.4 litres of detergent required.
- Cold wash rate / acid rate: 200 litres x 1% = 2.00 litres of detergent required.
Some products describe the usage rate in a way such as 400ml per 45 litres of water. In such cases, you divide the volume of water that you have available for washing by the stated volume on the label and multiply the answer by the detergent volume. (200 litres/45 litres = 4.44 x 400mls = 1.78 litres of detergent required).
4). Check to see if your auto washer is using the correct amounts of detergent. This can be done by:
- Placing a volume of chemical into a jug with the volume in the jug greater than the volume needed by the machine.
- The bottom of the pipe must be touching the bottom of the jug to maximise “suck up” capacity.
- Take care not to mix up the “suck up” pipes – blue pipe for caustic detergent and red pipe for acid.
- Use appropriate protective equipment when handling chemicals and ensure that open jugs cannot be easily accessed by pets or children.
5). Run the wash cycle as normal.
6). Check the jug to see what volume of detergent remains after the wash and subtract the volume that remained from the initial volume placed in the jug to deduce how much was used.
7). Check if the amount used agrees with the calculation from step three above.
8). This exercise must be undertaken separately for hot caustic, cold caustic and acid washes.
9). In the event of over or under use, contact your service technician to recalibrate the auto washer.
The biggest issues with automatic milking machine cleaning is the usage settings not allowing for increased usage rates when required for cold circulation cleaning.
Hot wash temperatures
Check the temperature of the hot wash solution just before it is drawn into the machine for washing; it should be 75–80oC at the start of the cycle. Do not depend on the temperature of the water on the thermostat or the tap as this is not reflective of temperature in the trough.
If the hot wash temperature is not reaching these levels: have your heating system inspected by a professional and adjusted to achieve these temperatures if possible; reduce the amount of time that it takes to fill the trough with hot water to reduce heat loss by increasing the water pressure and/or increasing the diameter of the pipe filling the trough and/or cover the trough to minimise heat loss with either a steel or perspex lid.
To effectively wash a machine with chlorine free liquid chemicals, a minimum of seven hot washes are required. Three acid washes are also required and these can be included in or applied in addition to the seven hot washes.
Detergent circulation time
Eight to ten minutes is a more than sufficient amount of time for a hot wash to circulate in the milking machine. Circulation of detergent solutions for >10 minutes will likely result in the solution temperature dropping below 45oC, which has a negative effect on cleaning efficiency. It would be advisable to stay in the dairy during a wash cycle and time the wash on your phone or watch to see if it is within this recommended time frame and if not have it adjusted by your service technician.
Machine drainage
Observe the milking plant to see whether it is draining effectively. Drain points are usually located near the milk pump in the pit (to drain the receiving vessel) and on the wash line (in low line plants). These may be automatically operated or need to be manually opened. Either way it is vital that they serve their purpose and expel as much water from the plant as possible between wash cycles.
Poor drainage can result in low circulation temperatures in hot wash solutions due to the mixing of retained cold rinse water with hot detergent solutions. Thereby, reducing the efficacy of the wash and wasting energy and money heating water that cannot be used to its full potential.
Poor drainage of final rinse water can also have a negative impact on milk residue levels; especially where chlorinated water (which will almost always contain chlorate) is used for cleaning. Water containing chlorate that remains in the plant will enter the bulk milk tank as it will mix with the first milk through the line. Therefore, this is liable to cause chlorate contamination of the bulk milk tank.
Utilise useful features
Warm rinse
Some types of auto washers are fitted with a function allowing a post milking warm rinse to be conducted; 30oC is sufficient as it will aid in the removal of milk fat deposits and is very beneficial during late lactation when fat levels in milk are higher. Keeping the pipework warm will contribute towards the maintenance of the temperature during the hot circulation cycle provided all other aspects of the machine are working correctly.
Discarding the first wash solution through the line
Some types of auto washers have the facility to discard the first portion of water that goes through the machine at the beginning of the hot circulation wash. The amount of water sent to waste is based on time and is adjusted until the water temperature is suitable for circulation. Only after the appropriate temperature is reached will the detergent be added to the trough. This function combined with effective drainage of the plant, adequate initial water temperature and adequate detergent usage rates can maximise the efficacy of your hot wash.
Bulk tank cleaning
A bulk tank should use a volume of water that is equivalent to 1-2% of the tank’s volume for washing. For example – 5,000 litre tank x 1.5% = 75 litres of water used for washing, 75 litres water x 0.7% = 525mls of detergent required for a hot wash. It is recommended that a bulk tank is descaled at least every third collection. If using a fully automatic system and you do not know the frequency of descaling your tank ask your tank technician to check this and set it up if necessary, at the correct volumes.
The biggest issues regarding bulk tank clean on farms are detergent suck up tubes in the wrong drums (red for acid, blue for detergent) and no acid being used.
This article first appeared in the Milk Quality Farm Walk booklet from the Connelly family, Tuam, Co. Galway, who were winners of the NDC and Kerrygold Quality Milk Award for 2022.