Maintenance of Milking and Milk Handling Equipment
|History:||Reprinted, July 1989|
|Written by:||G.A. Garland - Head, Engineering Section, New Liskeard College of Agricultural Technology|
Table of Contents
- Milk Cooler
- Refrigeration Unit
- Vacuum Pump
- Vacuum Control Valves or Regulators
- Vacuum Pipeline
- Vacuum Reserve Tank
- Milk Claw
- Milk Pipeline
- Milk Receiver Jar
- Milk Pump
- Testing Equipment
Following a program of preventive maintenance can bring great benefits to the dairyman by eliminating unnecessary service calls and down time, and by minimizing the chance of a major breakdown or permanent damage to a vital piece of equipment. The operator should know not only how his milking system works, but also what regular inspection and servicing it needs to keep it performing at near new efficiency.
A checklist and maintenance suggestions are given below to help the dairyman to keep his milking system in top working condition.
- Check the agitator motor for grease leaks or noisy operation, also worn shaft shields and bearings.
- Replace leaking agitator motor seals. Tighten bolts holding motor mounting brackets. Replace worn shaft shields and bearings.
- Replace timer if not functioning properly
- Replace thermometer if faulty.
- Replace valve "O" ring, if leaking.
- If running time is too long check and clean condenser coil. Check refrigerant.
- The presence of foam indicates air indicates air leaks in the milking system or excessive agitation of the milk;
- churned milk (clumps of fat floating on the surface) usually is caused by excessive agitation and slow cooling of the milk. Check refrigerant; and
- frozen milk on the surface or as layers of ice on the bottom of the tank. The freezing of milk can be avoided by turning on the refrigeration when the milk level reaches the level of the agitator blades and setting the tank thermostat so that the milk is cooled to 4° C (38 to 40° F).
- Check condenser coil for dirt or dust - air must flow freely through the coil and exit into the atmosphere.
- If condensor coil is dirty turn disconnect switch to "off" position, brush wash with milk detergent solution, rinse with tap water from the fan side out and allow to drain for three hours before restarting.
- Call to the attention of refrigeration service man, any air or refrigeration leaks.
- If refrigerant is foaming, have refrigerant added by serviceman.
- Call to the attention of refrigeration service man any malfunction of the condensor fan motor.
- Check oil level weekly.
- Fill with correct type of oil recommended by manufacturer. Some oils contain additives which form a sludge when mixed with water and detergent. Do not overfill - excess oil will blow out exhaust.
- With v-belts care must be taken that the belt section used matches the the correct section pulley, for example, B section belting should not be use on A section pulleys. Tighten drive belts so there is a slight sag on the slack side while running. Repair or replace worn vanes, bearings and drive belts.
- Once every six months, or when the pump becomes fouled by milk, it should be cleaned using diesel fuel or a 4:1 kerosene-oil mixture. Approximately two pints of mixture are fed into the suction port while the pump is running. If extensive cleaning is required, the pump can be filled with this mixture and allowed to soak. After the pump is cleaned half a pint of oil should be added through the suction port to ensure thorough lubrication.
- The exhaust pipe must never be smaller than the outlet from the pump, otherwise pressure will seriously limit the performance of the pump. Elbow bends should not be used as they are too restrictive. Bends with large radii are better. A non-return valve should prevent reverse rotation when pump is switched off.
- Every six months have vacuum pump capacity checked by service man to help detect wear, leaks or stoppage in the system.
Vacuum Control Valves or Regulators
- Check the location of regulator.
- In bucket systems the regulator should be placed in a clean
spot on the vacuum line between the reserve tanks and the first
stall cock. In milk pipeline systems the regulator should be
- between the vacuum reserve tank and the sanitary-trap near the milk receiver, or
- on the vacuum reserve tank.
- The regulator must be capable of admitting air at least equal to the capacity of the vacuum pump. All milking systems should be equipped with a vacuum relief valve set 2 or 3 inches higher than normal line vacuum, for safety in event of regulator failure.
- Regulator valves, valve seats, screens and filters should be dismantled and thoroughly cleaned at least twice a year unless regulators are unavoidable in a dusty location then they should be cleaned more often. Do not oil valves or moving parts since this will only collect dust and dirt and make the valve stick.
- Check the pulsation ratio. The pulsation ratio refers to the length of time the inflaction or liner is in the "milking" phase compared to the "rest" phase. This can only be checked by special test instruments.
- Example pulsation ratios are 50:50 and 60:40. Know what is recommended for your equipment and report any malfunctions to the service man.
- The recommended rate is in the range of 50 to 60 pulsations per minute. This depends on such things as pulsation ratio, vacuum level and type of inflation. Know and follow manufacturer's recommendations to keep these factors in balance. Do not experiment on your own.
- Older type pulsators need frequent cleaning of air inlets and occasional replacement of valve rubber seals. Some can be wahed out regularly, but check manufacturer's recommendations before bringing in contact with water.
- Report problems to a service man.
- Check stall cocks for leaks.
- Tighten or replace faulty stall cocks.
- Adjust or replace.
- Flush vacuum pipeline with hot water and a non-foaming detergent.
- Adjust or replace.
Vacuum Reserve Tank
- Check capacity of tank.
- Tanks should at least have 5 gallon capacity for each milker unit used.
- Replace tank if necessary.
- Flush to keep clean.
- Check short air tubes on milker units.
- Never milk with holes in pulsator air tubes.
- Discard any inflation of liner with holes or cracks. Discard any liner than has passed the number of cow milkings recommended by the manufacturer: for example 1000 cow milkings.
- It is recommended that two sets of liners be kept on hand. One set stored in a lye solution and used on alternate weeks.
- Check air admission hole ("air vent").
- Clean air vents thoroughly. Slow milking and/or flooding of claw could be caused by blocked air vents. Do not increase vent size.
- Clean and replace any defective claw parts.
- This test will determine if a constant, steady vacuum exists at the teat cup at all times during milking.
- Check for proper slope.
- Maintain slope of 40 mm per 3 m (1 1/2 in. per 10 ft) downward, towards the milk receiver jar from the high point in the line.
- Maintain inlets in the top third of the pipeline to prevent vacuum fluctuations. Make sure valves close properly to prevent vacuum losses.
- To prevent vacuum losses tighten couplings; clean and/or replace gaskets.
Milk Receiver Jar
- Check gaskets, fittings and non-return valve for leaks.
- Clean and/or replace gaskets. Tighten couplings.
- Report "unexplained" buildups to service man.
- Check bushings, seals and diaphragms.
- To assure proper performance and sanitation make necessary adjustments or replacements.
Dairy farmers may do much to maintain the performance of their milking and milk handling equipment but to locate many faults, regular checks by a person skilled in the use of the necessary scientific testing equipment are necessary.
Milking machine efficiency often deteriorates gradually, unnoticed by the farmer. It is for this reason that it is advisable to have the system tested at least twice a year. These tests are designed to locate faults in the operation of the vacuum pump, vacuum regulator, vacuum gauge, pulsators and inflations. The air reserve is measured and if inadequate the reason for the low reserve is determined.
In many cases, small repairs or adjustments to the equipment on the spot will restore its efficiency.
For more information:
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