The basic aspect of packaging systems using multi-use containers is collection of empty containers and washing these prior to refilling. There may be need for intermediate storage of unwashed as well as washed empties, depending on capacities of machines and operating times. Storage of unwashed containers is normally essential and may extend overnight so that washing and filling operations begin next morning before the day’s load of unwashed empties arrives. Storage of washed cans is permissible as cans have lids, but storage of washed bottles is a bad practice as they do not have lids and are exposed to contamination. Filled cans and bottles normally need refrigerated storage to synchronise with the distribution timings and arrangements. The storage and operational requirements are depicted schematically in the following figure.
There are two types of bottle fillers in operation, the gravity fillers and the vacuum fillers. In both the types, the filling force is the force of gravity. While one filling tank is maintained under atmospheric pressure, the unit using vacuum filling is under negative pressure. The head of milk over the bottle determines the speed of filling. The filling nozzles in both types are arranged in a circle. Bottles are fed from the bottle washer into the filler in a single row. On this single lane conveyor, the bottle in-feed to the filler may be stopped by a bottle stop. This bottle stop is free to rotate under normal circumstances. But if the operator wishes to stop the machine for any reason, the clutch-operated bottle stop would prevent further movement of bottles to the filling machine.The main components of the filling machine are the float chamber, the filling nozzles and the supports. The assembly of supports revolves the bottles, which are automatically fed into the bottle supports or lifts. Each support raises the bottle in it so that its mouth is pressed and sealed against the rubber gasket of the filling nozzle. The efficiency of this seal depends on the bottleneck finish, hardness and state of the rubber gasket and the sealing pressure. The bottle is now in the position to be filled, being arranged just below the filling valve and the product to be filled in the filling bowl.
The milk flows into the bottle while it still moves along the assembly. The bottle filling valves are opened and closed by a lever from cams fitted to the stationary filling frame. The valves are triggered as the filling bowl and consequently, the valve-activating lever pass the cam. In case no bottle is in position, the centering bell does not lift and therefore, the situation can be sensed. This is a mechanical system to ensure that the filling valve is not activated. Therefore, no filling takes place when no bottle is in place, thus avoiding spillage and losses. After the bottle is filled, just prior to completing a full revolution, the bottle is automatically brought down and an empty bottle takes its place.
Gravity fillers: The bottle-filling system works on the same principle as filling a bottle under a tap from an overhead tank. However, certain conditions are to be fulfilled for the efficient and automatic working of the system. Firstly, the filler bowl should have enough liquid (milk). This is easily achieved by installing a float, which closes the connection to the main tank when the bowl is filled and opens up when the milk level falls.The next step is to ensure that the bottle mouth is adequately sealed to the filler bowl. To achieve this, the bottle is connected to a filling tube attached to the filling bowl. In the simplest design, this is achieved by placing the bottle on a stirrup that could be lifted up to seal against the gasket on the filler bowl. Therefore, the neck design and quality of the bottle should be capable of creating this seal. Once the bottle is sealed to the bowl, the flow of milk can start. To control the flow, the filling valve in the filling tube opens to start the flow and closes when the bottle is filled.The lifting stirrup is then lowered and the bottle is removed from the filler and the next empty bottle is introduced into the line.The pressure head from the top of the filling bowl to the outlet of the filling valve provides the ‘driving force’ or the ‘gravitational force’ to fill the container.
Vacuum fillers: In this case, the filling bowl is closed and as opposed to the gravity fillers, which work under atmospheric pressure, a negative pressure of about 0.05 bar is applied to it. The bottle is placed in position such that an airtight seal is created between the filling bowl and the bottle to be filled. However, this type of filler is not suitable for liquids of low viscosity that tend to foam. This is because the liquid in the balance tube is sucked back into the filling bowl owing to the vacuum that exists, as the bottle is lowered from the seal on the filling bowl.Therefore, vacuum fillers are normally used for liquids of higher viscosity.
Bottle-filling and capping are related activities and have to be considered in combination with one another. The filled bottles move in a smooth continuous fashion to the capping section. A movable support raises the bottle against the capping machine.The rising bottle activates a mechanism that slides a cap over the bottle and then brings the capped bottle against a plunger. The plunger is backed by a spring so that the cap is forced onto the bottle under regulated pressure.The most commonly used closures for bottles are aluminium caps and crown corks.The former has a thickness ranging from 0.04 to 0.06 microns. The cap should cover the bottle mouth entirely and should be sterilized before use. Crown corks are the oldest types of closures and are sill used widely in the beverage industry.They are made from precoated tin plate or tin-free steel sheets. These sheets pass through a press tool machine, which produces discs and also shapes them into crowns with corrugated edges. A liner is inserted in the crown. This compounds the crown and also acts as the main seal. When closing the bottle, a vertical load is applied to the bottle to ensure that the liner is pressed on to the neck finish. At the same time, a specially designed circular disk is forced onto the crown edges,forcing them inwards and making a lock around the edge of the bottle mouth.Crown corks are normally used for sterilized milk bottles.
Bottle washing machines work on any of the following principles: 1) Spray or hydro-rotary, 2) straight-through soaker hydro type and 3) soaker type.The jet or spray type washer sprays the inside and outside of the bottle with jets of washing solutions. This design is simple and compact. It is, however, not as efficient as the soaker type. Its initial cost, however, is less than the soaker type machines. It is more suited for smaller plants.
The come-back-soaker-hydro machine is the most common in large dairies. Bottles are kept soaked in a strong alkali solution for some time (~ 5-10 min). An endless(round) conveyor carries the bottle carriers through the washer.The typical washing sequence (Fig. 10.4), in which the carrier conveyor chains dip in and out of the soak tanks allowing sufficient type for soaking consists of the following steps:
Whatever the principle on which the bottle washer works, the following basic conditions should be fulfilled by the machine.
After bottle washing, inspection should be done for dirty bottles, chipped bottles,residual liquid and foreign objects in bottles.
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| Sequence of operations with multi-use containers |
Thus, packaging in bottles may be explained in two phases: first, the bottle filling operation along with the bottle-capping process and second, the bottle washing operation. Bottles with wide necks (36 to 40 mm), suitable for sealing with aluminium foil caps made in place from reeled strip, forms the most common system for packaging of pasteurized milk in multiuse containers. Bottle washing,filling and capping machines should be of matching capacity, otherwise the labour-intensive operations of filling and emptying crates, unstacking and stacking would have to be repeated unnecessarily. This problem does not arise with cans, since they are not crated and may be easily stored empty after cleaning.
i. Bottle Fillers
There are two types of bottle fillers in operation, the gravity fillers and the vacuum fillers. In both the types, the filling force is the force of gravity. While one filling tank is maintained under atmospheric pressure, the unit using vacuum filling is under negative pressure. The head of milk over the bottle determines the speed of filling. The filling nozzles in both types are arranged in a circle. Bottles are fed from the bottle washer into the filler in a single row. On this single lane conveyor, the bottle in-feed to the filler may be stopped by a bottle stop. This bottle stop is free to rotate under normal circumstances. But if the operator wishes to stop the machine for any reason, the clutch-operated bottle stop would prevent further movement of bottles to the filling machine.The main components of the filling machine are the float chamber, the filling nozzles and the supports. The assembly of supports revolves the bottles, which are automatically fed into the bottle supports or lifts. Each support raises the bottle in it so that its mouth is pressed and sealed against the rubber gasket of the filling nozzle. The efficiency of this seal depends on the bottleneck finish, hardness and state of the rubber gasket and the sealing pressure. The bottle is now in the position to be filled, being arranged just below the filling valve and the product to be filled in the filling bowl.
The milk flows into the bottle while it still moves along the assembly. The bottle filling valves are opened and closed by a lever from cams fitted to the stationary filling frame. The valves are triggered as the filling bowl and consequently, the valve-activating lever pass the cam. In case no bottle is in position, the centering bell does not lift and therefore, the situation can be sensed. This is a mechanical system to ensure that the filling valve is not activated. Therefore, no filling takes place when no bottle is in place, thus avoiding spillage and losses. After the bottle is filled, just prior to completing a full revolution, the bottle is automatically brought down and an empty bottle takes its place.
Gravity fillers: The bottle-filling system works on the same principle as filling a bottle under a tap from an overhead tank. However, certain conditions are to be fulfilled for the efficient and automatic working of the system. Firstly, the filler bowl should have enough liquid (milk). This is easily achieved by installing a float, which closes the connection to the main tank when the bowl is filled and opens up when the milk level falls.The next step is to ensure that the bottle mouth is adequately sealed to the filler bowl. To achieve this, the bottle is connected to a filling tube attached to the filling bowl. In the simplest design, this is achieved by placing the bottle on a stirrup that could be lifted up to seal against the gasket on the filler bowl. Therefore, the neck design and quality of the bottle should be capable of creating this seal. Once the bottle is sealed to the bowl, the flow of milk can start. To control the flow, the filling valve in the filling tube opens to start the flow and closes when the bottle is filled.The lifting stirrup is then lowered and the bottle is removed from the filler and the next empty bottle is introduced into the line.The pressure head from the top of the filling bowl to the outlet of the filling valve provides the ‘driving force’ or the ‘gravitational force’ to fill the container.
Vacuum fillers: In this case, the filling bowl is closed and as opposed to the gravity fillers, which work under atmospheric pressure, a negative pressure of about 0.05 bar is applied to it. The bottle is placed in position such that an airtight seal is created between the filling bowl and the bottle to be filled. However, this type of filler is not suitable for liquids of low viscosity that tend to foam. This is because the liquid in the balance tube is sucked back into the filling bowl owing to the vacuum that exists, as the bottle is lowered from the seal on the filling bowl.Therefore, vacuum fillers are normally used for liquids of higher viscosity.
ii. Bottle Cappers
Bottle-filling and capping are related activities and have to be considered in combination with one another. The filled bottles move in a smooth continuous fashion to the capping section. A movable support raises the bottle against the capping machine.The rising bottle activates a mechanism that slides a cap over the bottle and then brings the capped bottle against a plunger. The plunger is backed by a spring so that the cap is forced onto the bottle under regulated pressure.The most commonly used closures for bottles are aluminium caps and crown corks.The former has a thickness ranging from 0.04 to 0.06 microns. The cap should cover the bottle mouth entirely and should be sterilized before use. Crown corks are the oldest types of closures and are sill used widely in the beverage industry.They are made from precoated tin plate or tin-free steel sheets. These sheets pass through a press tool machine, which produces discs and also shapes them into crowns with corrugated edges. A liner is inserted in the crown. This compounds the crown and also acts as the main seal. When closing the bottle, a vertical load is applied to the bottle to ensure that the liner is pressed on to the neck finish. At the same time, a specially designed circular disk is forced onto the crown edges,forcing them inwards and making a lock around the edge of the bottle mouth.Crown corks are normally used for sterilized milk bottles.
iii. Bottle Washers
Bottle washing machines work on any of the following principles: 1) Spray or hydro-rotary, 2) straight-through soaker hydro type and 3) soaker type.The jet or spray type washer sprays the inside and outside of the bottle with jets of washing solutions. This design is simple and compact. It is, however, not as efficient as the soaker type. Its initial cost, however, is less than the soaker type machines. It is more suited for smaller plants.
The come-back-soaker-hydro machine is the most common in large dairies. Bottles are kept soaked in a strong alkali solution for some time (~ 5-10 min). An endless(round) conveyor carries the bottle carriers through the washer.The typical washing sequence (Fig. 10.4), in which the carrier conveyor chains dip in and out of the soak tanks allowing sufficient type for soaking consists of the following steps:
- Pre-rinse with tap water, warm clear water or the overflow from the final rinse tank. The bottles are either jetted with water or soaked. Water temperature: ~35-40° C.
- Empty the residue in bottles.
- Prerinse using warm water. Water temperature: ~ 55° C.
- Soak in hot solution of strong alkali. Solution strength depends on its temperature and soaking time. (usually ~ 3% alkali, 55° C, 5 min soaking). Temperature ranges unto 80° C with alkali solutions of 1-3% strength.
- Scrub with solution. Bottles are exposed to hot solution jets at high pressure from inside and outside to dislodge stubborn particles that stick to surfaces.
- Rinse bottles with warm water. Water temperature: ~ 60° C.
- Repeat the above two steps at ~ 80° C.
- Invert the bottles to empty contents.
- Pressure rinse with warm water inside and outside. Water temperature: 35-40° C or higher. This water is not circulated, but is normally routed to the pre-rinse tank. Empty the bottles.
- First rinse with fresh water. Jets from inside and outside. Empty the bottles.
- Final rinse with fresh water. This water may be chlorinated to ensure sanitisation.
- Sodium hypochlorite of strength 25-50 ppm of available chlorine. Empty the bottles.
Whatever the principle on which the bottle washer works, the following basic conditions should be fulfilled by the machine.
- The cleaning and sterilizing solutions should reach all corners inside and outside of the bottles being washed.
- Sufficient contact time should be allowed for efficient washing and cleaning.
- Different solutions should be in individual chambers and should not be allowed to mix.
- There should be of predetermined concentration and should not be diluted with rinse water or steam injections.
- The temperature and strength of detergent solutions should be maintained.
- Soft water should be used.
- Cleaning solutions should be changed at least once a week and all tanks are cleaned.
- If hard water is used sodium gluconate and/or tetrasodium pyrophosphate should be added to the washing solutions.
- A 15% solution of muriatic acid along with an inhibitor may be used as a descaling agent in bottle washers.
After bottle washing, inspection should be done for dirty bottles, chipped bottles,residual liquid and foreign objects in bottles.
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