How to Start a New Hygiene Investigation

Make sure you have internet connection before you go out to a farm. Once you have accessed the individual farm in the ‘Home-Farms’ Screen, you can start a ‘Hygiene Investigation’ from the main Dashboard, which takes you to the ‘Actions’ screen, select ‘Create New’ button in bottom right corner.  Once your farm details are entered and you are ready to go out to a farm, we recommend you ‘Sync’ the details so your information is saved on the server and is accessible if internet connection is not available at the farm.  The ‘Sync’ button is located in the individual farm ‘Actions’ Screen in the bottom left corner.

There are 16 steps to a full investigation where you fill in the farm equipment and test details and click ‘Save and Continue’ to progress to the next screen, or if you want to go back one screen, click the back arrow in the top left hand corner of your screen. There is also a progress bar at the bottom of the screen to allow you to skip to previously completed screens.  To resume later, click ‘Save and Exit’

Gab – this could go in the ‘Home-Farms’ Screen


How to Continue with an Investigation in Progress

At the main Home-Farms Screen, select the Farm, then in the Individual Farm Dashboard, select ‘Hygiene Investigation’ then the ‘In progress’ investigation you wish to continue with. Work through the 16 investigation screens, ensuring you ‘Save and Continue’ to progress. To leave the Investigation without completing, select ‘Save and Exit’ in the bottom left corner and the Investigation will remain ‘In Progress’.

Gab – this should go in the individual farm ‘Actions’ screen


How to invite others to join an Investigation created by you

Invite other users to work with you on this investigation.  Only one user can add or edit information in this investigation.  This user is referred to as the Lead investigator.  Only the Lead can invite others to collaborate.  The Lead can assign an invitee to become the Lead.  This is useful for users that may initiate an investigation but would like others to take the Lead role to complete it.

To invite another User to join in an investigation, select the farm to be investigated (this can be an existing or a new one). In the first screen 1/16 ‘Description of Presenting Problem’ scroll down to the section “name_email_mobile” and insert details or if they are a User already active in other farms on your device, you can ‘Search by Name’ or ‘Search by Email’.  Select ‘Search’, highlight the desired user, ‘Use Details’. To hand over primary control to the User, select the button beside their name. You will still be able to view the investigation, but no longer be able to enter data unless the new Lead User reassigns control to you. If you click the button by mistake, you can correct it any time until you next sync the device, however you should apply caution to make sure you don’t lose ownership by mistake.

Gab – this should go on the ‘Description of presenting problem’ screen


How to Accept an invitation to join a Farm or Investigation created by someone else

If another Dairy Hygiene Helper User invites you to join in a Farm or an Investigation, you will find their invitation in the ‘Home-Invites’ Dashboard. If you wish to accept the invitation select ‘tick’ or to decline select ‘cross’.

Gab – this should go on the ‘Home-Invites’ screen


How to Sync data

This app is designed to be used when there is no internet connection available so the device is not constantly roaming for a signal when out of range it is not automatic.  This means that a manual sync is required to update the data stored on the device to the database.  The Sync button is found in the Farm Actions screen, bottom left corner.  It is recommended that you sync your device prior to visiting a farm and then again when you have internet connection.


Description of Presenting Problem

Clearly describe the problem as it currently presents. Has the investigation been initiated by a high Bactoscan result, Thermoduric count, other factors (e.g. visible cleaning failure) or a combination of all?

Provide plenty of details about history, circumstances, and what the objective(s) for the investigation might be.

Provide the latest Bactoscan/TPC and Thermoduric test results.


More about cleaning-related milk quality tests

Below is a list of cleaning-related tests (and test protocols) that are conducted on samples of milk taken from the bulk milk tank.



Any Changes?

Make notes of recent changes to:

Milking equipment – recent upgrades, replacement of components (e.g. vacuum pump), repairs or breakdowns, major services. Flooding of the system – during milking or during cleaning.

Cooling equipment – changes to cooling equipment, changes to temperature of the milk entering the bulk milk tank, plat cooler pump issues, water supply issues, cooling times, pick up schedules.

Cleaning & water heating equipment – changes to HWSs such as element failures, electrical problems (e.g. circuit breakers being activated), corrosion, water not being heated to expected temperature(s), thermostat issues, chemical dosing pumps failing (e.g. blockages, split tubes). Changes in wash controller. Level probes not working as intended, butterfly valve failures, air  injector failures.

Wash program – changes in chemicals, cycle volumes, number of cycles deployed, recirculation times, water sources.

Wash routine – timing of the wash, changes to steps usually followed, filter sock use, milk and cleaning solution purge times, changes to chemical measuring apparatuses. Changes in wash routine instructions. Skipping of tasks/steps due to time/staff/financial constraints.

Staff changes – new/different milking/relief staff, time pressures and staff pressures (less staff to do the same jobs). New staff yet to be trained.


Water Details

Water Sources
Identify the (current) sources of water that supply both the hot water service(s) and cold water taps. Be mindful that different sources may be used for different cycles of the wash. For example, bore water may be used for the pre-rinse cycle and rain water used for all other cycles.

More about water sources

Hardness can vary between sources and from the same source at different times of the year. If the water is found to be hard, then commercially available water softening systems should be incorporated, if an alternate better quality water supply is unavailable.  Water used in a dairy may come from very different sources. When designing a dairy wash program, it is prudent to assume that the water, regardless of its source, may have microbes present.  Only the water from the hot water cylinder (if it is working correctly i.e. > 90 ºC) should be considered microbe free.

Water Quality Results
Unlike many other dairying countries, water quality poses the greatest challenge to cleaning in Australia. It is generally poor and can be highly variable, even from the same source.  The best quality water should be used for cleaning the milking machine and milk vat. It should be potable water – suitable for human consumption. Two commonly used indicators of water quality are hardness content and microbial contamination. Suspended solids, organic matter, chemicals, and odours are other indicators of water quality.

A specialised water test kit is required to determine qualities such as iron and hardness. Dairy chemical representatives are usually the best starting point to working out which type of water test kit is most appropriate for assessing dairy farm water and cleaning solutions.

Often, the best place to sample water for quality testing is from the hot water service.

More about water quality


Suspended solids and organic matter

Water containing suspended solids and/or organic matter can dramatically reduce cleaning performance and effectiveness. Often detergents with greater dissolving, emulsifying, and dispersing capacities are needed to counteract the impact of ‘dirty’ water. Furthermore, chlorinated detergents (and sanitisers) can be deactivated when the water contains organic matter.


E. coli count and total plate count
Water that is heated and stored at high temperatures (>80ºC) for long periods of time (hours) can be considered free of microbes usually associated with contamination of dairy farm milk.  However, water that has not been heated and held at hot temperatures may contain such organisms.  Therefore, it can be informative sometimes to test the water for E. Coli (or perform a more general test such as Total Plate Count) to assess the level of contamination and whether this might be a contributing factor in dairy hygiene related issues; especially when only cold/cool/warm water is used for cleaning. Discuss the results with the testing laboratory to ascertain their significance.


Iron in water
The iron content of water must be taken into account when selecting detergent programs for cleaning dairy equipment. Iron can be present in water in a number of forms; soluble iron, which cannot be seen and insoluble iron, which precipitates out of the water. The presence of iron radically reduces the effectiveness of alkaline detergents. It is also the main food source for ‘iron-loving’ bacteria. Iron will stain equipment at concentrations as low as 0.3 ppm. If the iron content of rinse or wash water is high, the wash program should be adjusted to include more frequent use of acid detergents.


Water hardness
Hardness is determined by the mineral content present in the water. Calcium (Ca) and magnesium (Mg) in the form of carbonates are the two most prevalent minerals. Iron (Fe) is another mineral that is often found in elevated levels in many dairy farm water supplies.  In Australia, a commonly used measure of water hardness is total hardness and is expressed  as mg/L or ppm of calcium carbonate (CaCO3). An example of different classifications of water hardness is given in the Table below.

The softer the water is the better its quality and the greater its range of uses. The harder the water is, the less suited it is for cleaning.
Hard water means:

• more chemicals are needed to compensate for reduced cleaning action
• more complex alkaline detergents are required – those containing sequestering and chelating agents
• more frequent use of acid based detergents to dissolve the minerals and prevent build-up on equipment
• more corrosion of hot water heating elements and other milking equipment.



More about water hardness

Hard water is sometimes described as either ‘temporary’ or ‘permanent’ depending on which ions it contains. When temporary hard water is heated, calcium carbonate and/or magnesium carbonate precipitate(s). The resulting deposits can eventually lead to destruction of the heating element.  To protect the hot water system from temporary hardness, water should be
softened or an alternative water source found. Nowadays many dairy hot water systems contain ‘sacrificial anodes’ to help protect against hard water. The ions in the hard water ‘attack’ these sacrificial anodes instead of the hot water system. They need to be regularly checked and replaced before they are completely corroded.

Wash programs must be adjusted to compensate for the effect of hard water:

• more alkaline detergent must be used to clean milk residues from the milking machine
• detergents used in hard water should include sequestering or chelating agents. These
prevent scum formation and other forms of hard water precipitation by preventing the alkaline part of a detergent from reacting with the hardness ions and precipitating on to the internal surfaces of the milking machine.
For example, tripolyphosphate combines with the hardness ions and keeps them in solution, allowing the detergent to react with milk fat (saponification) and milk proteins.
• acid detergent should be used more frequently to assist in the removal of hard water

Green Cleaning Systems require water with a hardness of less than 150 ppm (CaCO3) and an iron level of less than 0.5 ppm.









































Equipment Inspection

It is important to undertake a visual inspection of the equipment to ascertain the current condition of components and the effectiveness of cleaning. The objective is not to assess the performance of the components – although some inferences could be made by their presentation – but rather the ability of their milk contact surfaces to stay clean and to oppose microbial colonisation. Furthermore, it is an opportunity to inform the diagnosis of the problem, and help in developing the remedy.

Visual inspections usually involve the dismantling of equipment. This can pose a challenge in many circumstances as it relies on the skills and know-how of the ‘inspector’, the tools required and on-hand, the complexity and layout of the equipment, the consent of the equipment’s owner, and above all, the consideration of safety. The reality is that the components that are inspected are those where access is safe and easy, dismantling is simple and quick, and the skills and tools required are few. In addition, the owner is also comfortable and reassured that all equipment will be returned to the ‘as found’ condition.

Undertaking a visual inspection requires a systematic approach. It follows the path of the milk from the cluster to the bulk milk vat. Other components are also inspected even though they may strictly not be in contact with the milk; they may have been exposed to milk vapour or have had milk enter through a malfunction.

When inspecting a component four considerations are needed.

  1. Is the surface clean or dirty? A clean surface is visually and physically free of any
    deposits, residues, stains etc.
  2. If deposits are found, what sort of deposit is it?
  3. What is the physical condition of the component? Perished, broken, cracked, etc.?
  4. What is needed to restore/rectify the situation so that the component can be deemed
    clean? (record this in the “comments & actions required” section.

If the component is clean, free of deposits, and in good service condition then it can be considered to have passed the inspection. If the component is dirty, contains deposits, or is in poor service condition then it can be considered to have failed the inspection.

It is important to note that a component that fails may not necessary infer that it is a causative factor in poor dairy hygiene. For example, a cracked claw bowl may fail the condition
component of the inspection but it may not be a reason for poor hygiene, even though it may pose a risk and therefore, should be replaced.

Using photos to record unusual or uncertain findings can then be shared with collaborators for input and contributory comments.


Milking Machine Wash Program Assessment

Select the wash session being assessed.
Complete the information for each cycle: cycle description, cleanser/sanitiser used, the dose rate, volume of the cycle, the temperature in the wash drum at the start of the cycle, and if the cycle is recirculated then the temperature of the cleaning solution at the exit/dump point.

Cycle volumes
A simple way to estimate the water quantity required to achieve adequate surface contact and minimise thermal loss is to use a guide based on the experience of Australian-installed milking systems. This guide uses the number of milking units to calculate the volume of each cycle. It suggests an average cycle volume of 6–8 L/unit; with 6 L/unit for small milking machines (up to 20 milking units) and 8 L/unit for larger milking machines (20 units and over). An average cycle volume value is given because some wash programs specify a higher cycle volume (e.g. 10 L/unit) for the first pre-rinse cycle but a lower cycle volume (e.g. 5 L/unit) for the subsequent cycles. Cycle volumes will need adjustment to accommodate individual circumstances, such as long milk delivery lines, and cleanser/sanitiser label directions. A guide to the minimum required cycle volumes is shown in the Table below.  A practical way to confirm sufficient cycle volume is to observe a recirculated cleaning cycle.  When wash water is recirculated the minimum volume required is equal to the volume needed to maintain recirculation without the water pick up pipe admitting air.

When recording the chemical dose rates, note the programmed (if auto dispensing) rate or rate given on the dairy’s wash instructions and compare this with what is actually dispensed.  Exercise appropriate safety when handling chemicals.

An example of wash session assessment is shown below. For each cycle to be assessed as a Pass each element – the volume, temperature (start and dump), chemical suitability, and
dose rate – must satisfy the minimum requirements of the specific wash program and the directions stated on the label of the dairy cleanser/sanitiser.

Some points to remember:
• Always measure/calculate the volume. Assumptions are often incorrect! Appendix 2 explains how to take volume measurements and perform the calculations.
• Exercise safety when measuring hot water temperatures.
• Be mindful at the time of measurement as to whether hot water has been recently drawn from the unit and if it has been replaced with cold water, thereby affecting the measurement taken.


More about selecting the right wash program

To determine a suitable wash program consideration must be given to:
i. the quality of the water supply – hardness level can act as proxy for water quality for this purpose
ii. the volume of hot water available
iii. the types of the products – cleansers & sanitisers

Use water quality & then hot water availability to select the most suitable wash program(s).  The numbers refer to the wash programs in the list below.

* Sufficient means, enough hot water to satisfy the day’s volume requirement for the pre-rinse, wash, and final rinse cycles. To estimate water quantity requirements, see the section titled Cycle volumes

Water hardness affects the effectiveness of alkaline detergents. Some detergents cannot be used in hard water. The presence of iron also has a detrimental effect: the higher the level of iron, the higher the alkali dose rate must be. Hence water hardness must be the first consideration.
Water that is extremely hard (>700 ppm, CaCO3, see hardness table), or has high levels of iron (> 3.0 ppm) can be considered to be of poor quality for cleaning purposes, and as such should be allocated to an acid-dominant wash program.


You can find details about registered cleansers and sanitisers, including label information, on the  APVMA’s PubCRIS database













Milking Machine Cleaning Solutions

Ensure PPE is worn.

A chemical test kit is required to assess whether the chemical characteristics comply with the requirements for effective cleaning.

The test should be conducted on cleaning solutions that have been made up but not used.

The tests to conduct are given in the Table below.

Chemical test parameters for cleaning solutions

Guideline for levels of active alkalinity based on soil loads

Before adjusting chemical dose rates, it is imperative to verify that the ‘presumed’ chemical dose is actually being delivered. Capture the chemical as it is dispensed to make the verification.


More about chemical energy

The reactions between the soil and the detergent are caused by chemical energy. These reactions are desirable because they tend to increase the solubility of the soil, reducing the overall energy requirement to clean. However, this is only true if the detergent is correctly matched to the soil. For example, alkaline detergent will not remove a limestone deposit whereas an acid will.

The physical/chemical properties of the soil also determine the optimal temperature for the reactions to occur. Generally, temperatures above the melting point of milk fat are necessary where milk-based soils are to be removed (see Table 8 on page 23). The rate of chemical activity is increased by increased temperature (refer to Thermal energy on page 30).

A well formulated detergent will have agents that contribute one or more desirable cleaning characteristics. The main cleaning objective is to remove the soil and leave the surface free of all soil and foreign matter. To achieve this goal, detergents should have the following properties:

  1. Wetting action: To penetrate the soil so the wash solution can contact all surfaces including the substrate.
  2. Dissolving and chemical reactivity: To bring the soil into solution.
  3. Emulsification and dispersion: To suspend soil in the wash solution.
  4. Water softening: To prevent the loss of alkalinity of the cleaning solution and to reduce scale and scum formation.
  5. Rinsability: To ensure removal of both soil and the cleaning solution.
  6. Disinfecting properties: To clean and disinfect. The chlorine in chlorinated alkalis acts to breakup protein deposits as well as kill microbes. Many different types of chemicals can be used to kill

Acid and alkaline detergents, and pH

The most commonly used detergents in the dairy industry fall into two groups: acids and alkalis.

Acid detergents provide the chemical energy to dissolve mainly mineral based deposits.

Alkaline detergents provide the chemical energy to dissolve organic (fats and protein) based deposits.

The main difference between acid and alkaline detergents is their pH values. The pH value indicates the concentration of hydrogen ions in a solution. The chemical power of a detergent is indicated by its pH. The pH scale is a logarithmic scale, so a pH of 4.0 is 10 times as acid (contains 10 times more hydrogen ions) as a pH of 5.0. Also, a pH of 13 is 10 times more alkaline than a pH of 12 (see below). The pH of a solution is easily determined by using indicator paper or a pH meter.

The pH scale showing the required range for acid-based and alkali-based dairy detergents is shown below.

Acid detergents

Acid detergents are formulated to provide the optimal pH for removing scale and mineral deposits. A low pH also makes it more difficult for bacteria to grow.

For an acid wash solution, the pH should be between 2.5 and 3.5.

Acid detergents are not affected by hard water, therefore, the label dose rate should, in principle, always guarantee a pH within this range. This however, will not be accurate if the water pH is too alkali.

Depending on the pH of the water supply and its buffer capacity (ability to resist pH change), a higher acid dose may be needed.

An acid works by releasing hydrogen ions in solution. Some acids are much more efficient at releasing these ions and are consequently stronger (see below). Therefore, one can’t say that a product is stronger simply by reading the concentration level on a label. The type of acid and its concentration dictate the relative efficacy: at the same acid concentration, the lower the pH the stronger the acid. Similarly, for alkalis; the higher the pH for equal concentrations, the stronger the alkali.

Please note that nitric acid is included here for illustration but is not recommended for use in cleaning milk harvesting equipment without adequate rinsing as it can be corrosive on stainless steel.

Alkali detergents

Alkali detergents are affected by hard water, therefore, dose rate adjustments will be required to guarantee optimal active alkalinity, pH, and chlorine level.

Active alkalinity – (sometimes referred to as AA) is a direct measure of the alkaline concentration of a given solution. It is determined by titrating an acid of known concentration against a fixed volume of alkaline wash solution.

The desired level of active alkalinity is affected by the soil load. The heavier the soil load (either from the water or the residues in the equipment) the higher the active alkalinity should be for the detergent to perform correctly. This is achieved by increasing the dose rate and/or selecting a detergent better formulated to cope with heavier soil conditions.

The Table below outlines active alkalinity levels under various soil loads in ideal (turbulence, time, & temperature) cleaning conditions.

To compensate for conditions where wash temperatures are lower, such as for bulk milk tanks, the active alkalinity must be increased. An active alkalinity of 2,000 to 3,000 is recommended.

For a wash solution containing a chlorinated alkaline detergent the pH must be between 11.5 and 12.5. For one containing a non-chlorinated alkaline detergent the pH must be at least 12.

Chlorine – when formulated into alkaline detergents at sufficient concentrations, can have a disinfecting quality by facilitating the removal of biofilms (Sundberg et al. 2011). For chlorinated alkaline detergents, the minimum chlorine levels (measured as available chlorine) should not be less than 70 ppm. For sufficient bactericidal activity, a minimum of 100 ppm is required.


Sanitisers are formulated to kill microbes. There are many types of sanitisers registered for use in the Australian market. They can be chlorinated or non-chlorinated; iodine-based, acid based, or alkaline based. Some sanitisers are combined with a detergent and perform both a sanitising and a detergent function.

Some sanitisers such as chlorine-based sanitisers (e.g. sodium hypochlorite) may be low cost and have wide anti-microbial properties but are easily inactivated in the presence of organic matter and can be highly corrosive (depending on concentration) on milk harvesting equipment. Furthermore, products such as sodium hypochlorite are not registered by the Australian Pesticides and Veterinary Medicine Authority (APVMA) for use in the cleaning of milk harvesting equipment.
















CIP Assessment

Flow through the cluster
Check to see that cleaning solution is flowing through every milking unit (cluster).  The flow should be turbulent and similar between clusters. Lack of turbulence despite apparently good flow may indicate a blocked/restricted air bleed in the cluster. Check and clear if necessary.

Air leaks between the liner mouthpiece and the jetter could also lead to reduced flow and high turbulence – depending on the size and nature of the leak.


Vacuum levels and effective reserve

Vacuum Level (Working Vacuum)
Is it appropriate for this installation? During the wash observe the vacuum gauge and compare this to what the reading is during milking (ideally they should be the same, though sometimes the vacuum level during cleaning is increased to improve cleaning performance).

For low line milking machines (where the milk line is positioned below the cows’ udders) the vacuum level should be at least 42-44 kPa.

For mid line milking machines (where the milk line is positioned level with the cows’ udders) the vacuum level should be at least 44-46 kPa.

For high line milking machines (where the milk line is positioned above the cows’ udders) the vacuum level should be at least 46 kPa.

These vacuum levels are only a guide as many factors (e.g. milk line height above the cows’ udders, pipeline sizes, cluster characteristics, milk delivery line height) will affect the appropriate vacuum level.
If the vacuum level is too low, the ability to transport the cleaning solutions through the milking plant will be compromised.


More information on Effective Reserve


Effective Reserve
Effective reserve relates to the milking machine’s ability to maintain the vacuum level at a given set point. It is governed by the capacity of the vacuum pump relative to the demands imposed by the operating equipment and by the milkers and cows.  In cleaning, adequate Effective Reserve is required to prevent the vacuum level from falling and therefore, compromising cleaning performance.

An easy way to assess the Effective Reserve is during the wash cycle when the wash solution is being recirculated and the air injector is operating. When a plant has adequate Effective Reserve (and an effective vacuum regulator sensor) then the vacuum level will not drop much – if at all – when the air injector activates to create the wash slug. The vacuum level may drop a couple of kPa (2-3) but will recover quickly (within 1-3 seconds) every time. If this does not happen, further investigation is required.



Slug Assessment

Slug flow
During the wash cycle count the number of slugs entering the receiver.

Slug speed can be estimated by following this method:
1. Determine the time, in seconds, from when the air injector turns on to when the slug enters the receiver.
2. Calculate the entire length of the milk line in metres.
3. Divide the length by the time to get the speed i.e. metres/second.

Example: A 25-unit herringbone with a looped milk line.
Time taken from when the air injector first turns on to when the slug entered the receiver is 4.1s.
The entire length of the milk line is 40 m.



More information about slug characteristics

Slug flow in the milk line and into the receiver.

During the wash cycle check the receiver to see that an effective slug is being produced.

For it to be effective it must:

  • Form and travel correctly. The rate of air admitted into the milk line by the air injector willdetermine the velocity of the slug and the time setting between air admissionsdetermines slug volume. The air injector ‘on-time’ (length of time the air injector admitsair for; typically, between 3.0 and ~5.0 s) should cease the instant before the slug entersthe receiver. If it ceases earlier than this then the slug will lose momentum and its‘quality’ and subsequent cleaning effectiveness will be compromised. Also, the sectionof milk line before the receiver may not be cleaned correctly.

  • If the air injector ceases (turns off) after the slug has entered the receiver, the enteringair will destroy the cleaning solution’s circular ‘swirl’ and reduce scrubbing action in thereceiver. Again, cleaning effectiveness will be compromised.
  • The slug must have sufficient volume to fill around 1/3 of the receiver. The receiver must be no more than 1/3 full when the slug enters. The force and volume of the slug shouldbe sufficient enough to cause the solution to ‘swirl’ around the entire receiver. Insufficient volume could be due to too short an interval between air admissions (air injector off-time is too short) or inadequate flow rate through the clusters to the milk line. Too much volume suggests the opposite situation.

The interval between slugs should be 20 – 30 seconds. This will allow between 12 – 15 slugs during the wash cycle – an ideal amount. On very large milking plants (70 units and more) this may be difficult to achieve.


Parameters for a quality slug to enter the receiver

Carefully listen for the air injector to “turn on” and then “turn off” while watching the receiver for entry of the slug of cleaning solution.  Determine when the slug enters the receiver. *It should be the instant after the air injector “turns off”.*
Estimate how full the receiver is just prior to the slug entering. It should be 1/3 full.
Determine the behaviour of the slug after it has entered the receiver. It should have strong swirling action.

Note: The air injector ‘on-time’ (length of time the air injector admits air for; typically, between 3.0 and ~5.0 s) should cease the instant before the slug enters the receiver.

Summary of slug characteristics and the factors by which they are influenced

Here is an example of good slug characteristics.


Here is an example of an ineffective slug.  Poor air injector settings mean that proper slugs cannot be formed.



Estimated cleaning solutions flow rate through clusters


A visual inspection should be undertaken first to identify any clusters that may have uncharacteristic flow patterns. If there are any correct these first.

Here is an example of correct (turbulent) flow through the cluster.



To measure flow through the cluster, you will need:
– test bucket
– large measuring jug
– stop watch.


1. Make a sketch of the layout of the wash system so the position of the clusters to be tested can be recorded.

2. Select approximately 10 % of the clusters to test. Include clusters nearest to and farthest from where the wash suction line joins the jetter line. Mark these on the sketch.  See example

3. Connect a test bucket to the first cluster to be tested. Start the wash cycle.

4. As soon as water enters the test bucket (use the claw bowl as an indication) start the stopwatch.

5. Continue to collect water in the test bucket for at least 3 minutes after which the vacuum to the cluster can be shut off and the timing stopped.

6. Measure and record (in litres) the volume collected in the test bucket using the measuring jug. Record the elapsed time (convert minutes:seconds to decimal.  For example, 3:30 = 3.5 minutes in the table.

7. Repeat the test until all the clusters have been assessed.

8. Complete the worksheet to determine the flow rate through each cluster tested.

9. Check to see if all individual values are between 3 – 5 L/min for small dairies (up to 20 units) and 10. 4–8 L/min for large dairies (especially those with weigh jar milk meters). If any are outside the guideline, investigation and retesting should be undertaken, particularly if flow rates are below the minimum.

11. Calculate the average flow rate by totalling the individual test values and dividing by the number of test values.

12. Divide the average flow rate value by 2 to determine the allowance. The allowance value is the maximum variability that is acceptable.

13. Check that all flow rate values fall within the allowance.

14. If test results indicate uniformity and sufficient flow rates no further testing should be required.

Alternative methods
Alternatively, a practical way to assess uniformity of flow between milking units is during herd test. When cleaning with the non-electronic herd test meters in place, check that the variation between the highest yield and the lowest is no more than 50 %.  Also, some milking machines with electronic milk meters may have capabilities to record and report on wash flow characteristics.



Bulk Milk Tank wash program assessment

Bulk Milk Tank wash programs

Almost all new bulk milk tanks sold since the mid-1990s have automatic cleaning systems. The degree of flexibility to adjust the wash program varies enormously between brands and between models within a brand. Often the wash programs are coded (similar to that on automatic wash controllers for milking machines) and may require a service technician to make adjustments.

The wash program for a bulk milk tank should follow the same principles as for cleaning milking machines. The program must include a pre-rinse, a wash, and a final rinse. The same requirements for water quality apply, although greater attention is required to ensure the water is free of suspended solids as these can block filters/strainers and spray heads.

There are two factors specific to cleaning bulk milk tanks that will influence the wash program. These are:

  1. Rinse requirements: After the milk has been emptied the milk contact surface inside the vat is cold. The milk residues are also cold and they will require greater effort to remove (compared to when they are at body temperature). Milk foam may be present and will also need removing. To minimise the risk of damage to the evaporator plates (on the other side of the milk contact surface) sudden changes in temperature are discouraged by vat manufacturers. To accommodate these conditions, the rinsing procedure is often different to that used for milking machines. There often are two rinses; the first is cold and its role is predominantly to remove the milk foam as well as the milk residue. The quantity of water used may be greater for this cycle. A second rinse is usually warm, it further removes milk residues and helps to raise the temperature of the milk contact surfaces in preparation for the subsequent hot wash. Some wash programs may combine the two rinse actions into one; i.e. the first part of the rinse uses water at ambient temperature which progressively becomes warmer.
  2. Temperature limitations: Again, to minimise risks of damage to evaporator plates, manufacturers place a maximum water temperature of 70 oC for cleaning inside the vat. This can affect the approach to sanitisation and the types of detergents used. Most vats source their hot water from a dedicated domestic main pressure hot water service (HWS). These typically have a maximum heating temperature of 70oC. Operating at lower temperatures may require higher dose rates of chemicals to be used.

Experience from the field has found that the wash programs (number of cycles, temperature of each cycle, cycle volume, and contact time) vary considerably among bulk milk tanks.  The Table below provides an example of the type of wash program that may be encountered. It is important to note that wash programs for bulk milk tanks do vary (e.g. some may perform three cycles, or four cycles).

Although the wash program characteristics for bulk milk tanks can be different to the wash programs for milking machines the six principles of cleaning still apply.

Complete the details for each cycle to determine whether all the essential steps are being covered.  Use this assessment to uncover and then correct the discrepancies.


Bulk Milk Tank cleaning solutions

Ensure PPE is worn.

A chemical test kit is required to assess whether the chemical characteristics comply with the requirements for effective cleaning.

The test should be conducted on cleaning solutions that have been made up but not used.

The tests to conduct are given in the Table below.

Chemical test parameters for cleaning solutions

Guideline for levels of active alkalinity based on soil loads

Before adjusting chemical dose rates, it is imperative to verify that the ‘presumed’ chemical dose is actually being delivered. Capture the chemical as it is dispensed to make the verification.



Include any additional tests, observations and/or findings that may have been made.

This may include any observations/assessments of the skills of the operators, wash routine deployed, or other factors that may contribute to the understanding(s) for the current hygiene issues.



Produce a list of specific action(s) that are required to rectify the situation and  mitigate the risk of the issue recurring.

Allocate the action to the person (this may not be the person who undertakes the action) who will take responsibility for the action to be completed.

Set an agreed date for the action to be completed.

If the person responsible for an action is a registered user of the Dairy Hygiene Helper they will receive an in-app notification.

Actions can be re-prioritised by pressing, holding, and then moving the icon (3 horizontal lines) at the right.


Recommended Milking Machine wash program

If a new wash program is recommended use the guide below to determine a suitable wash program.  If the wash program is automated ensure that the selected wash program (in the guide below) is available.

Use water quality & then hot water availability to select the most suitable wash program(s).  The numbers refer to the wash programs in the list below.

* Sufficient means, enough hot water to satisfy the day’s volume requirement for the pre-rinse, wash, and final rinse cycles. To estimate water quantity requirements, see the section titled Water quantity.
Water hardness affects the effectiveness of alkaline detergents. Some detergents cannot be used in hard water. The presence of iron also has a detrimental effect: the higher the level of iron, the higher the alkali dose rate must be. Hence water hardness must be the first consideration.
Water that is extremely hard (>700 ppm, CaCO3, see hardness table), or has high levels of iron (> 3.0 ppm) can be considered to be of poor quality for cleaning purposes, and as such should be allocated to an acid-dominant wash program.



The report of the investigation can be shared with an existing user (they will receive an in-app notification) or an email recipient.


Recommended Bulk Milk Tank Wash Program

If a new wash program is recommended and the wash program is automated ensure that the new wash program is available.


Check Progress

This is where progress on the allocated actions can be monitored.

If the “close” button is selected the investigation will be finalised and no further editing of this investigation will be possible.