Filling Equipments for Liquids:
For the filling, a means is provided for repetitively forcing a measured volume of the liquid through the orifice of the delivery tube designed to enter the constricted opening of a container.
The tube must freely enter the neck of the container and deliver the liquid deep enough to permit air to escape without sweeping the entering liquid into the neck of the container.
The delivery of a relatively small volume of liquid is usually obtained from the stroke of the plunger of the syringe.
A drop of liquid normally hangs at the tip of the tube after a delivery. Thus, a retraction device is designed as a part of the most filling machines.
Filling machines should be designed so that the parts through which the liquid flows can be easily demounted for cleaning and sterilization. It should be constructed of non-reactive materials such as borosilicate glass or stainless steel.
The pressure pump filler often is operated semi-automatically and differs from the gravity filler principally in that the liquid is under pressure.
Vacuum filling is commonly used in faster filling lines for large liquid volumes because it is more adaptable to automation. The vacuum draws the liquid from the reservoir through the delivery tube into the bottle. When the liquid level reaches the level of an adjustable overflow tube, the seal is mechanically loosened and the vacuum is released.
Emulsion and suspension often require specially designed filling equipments because of their viscosity. To obtain a reasonable flow rate, high pressure must be applied/ containers with large openings must be used. It is necessary to keep suspension and emulsion instantly agitated during filling so that the product remains homogenous.
Filling Equipments for Solids:
The rate of flow of solid materials tends to be slow and irregular whereas small, granular particles flow most evenly. Containers with large openings must be used even the filling rate is slow and the risk of spillage is present.
When the solid is obtained in relatively free-flowing form, machine methods of filling may be employed. This method involves the measurement and delivery of the volume of solid material which has been calibrated in terms of weight desired.
Another filling machine consists of an adjustable cavity in the rim of the filling wheel which is filled by vacuum as the wheel passes under the hopper. The contents are held by vacuum until the cavity is inverted over the container when a jet of sterile air discharges the dry solids.
Ampoules may be closed by melting a portion of the glass of the neck to form either bead seals (tip seals) or pull seals. Tip seals are made by melting sufficient glass at the tip of the ampoule neck to form a bead of glass and close the opening.
Pull seals are made by heating the neck of a rotating ampoule below the tip, then pulling the tip away to form a small, twisted capillary just before being melted closed. It is a slower process but the seals are more reliable than that from tip-sealing.
The heating with high-temperature gas-oxygen flame must be even and carefully controlled to avoid distortion of the seal.
Sealing Bottles, Cartridges, and Vials:
Rubber closures must fit the opening of the container snugly enough to produce a seal.
A faster hand method involves picking up the closure and inserting it into a vial using a tool connected to a vacuum line.
When closures are inserted by machine, the surface of the closure is usually halogenated or coated with silicone to reduce friction.
Aluminum caps are used to hold rubber closures in place. Single caps contain a hole/ center that is torn away at the time of use to expose the rubber closures. Whereas the double aluminum caps usually have an inner cap with a permanent center hole, which in use is exposed when the entire outer cap is torn off. The triple aluminum caps are used for large bottles with rubber closures having permanent holes for attachment to administration sets.
Automation of Processing:
When machines are designed/ used so that the constant attention of the human operator is required, the operation is identified as being semi-automatic.
For automatic operation, machines are usually linked together by conveyor belts in an arrangement that requires little attention from an operator.
The belts carry each vial in sequence to the filling wheel, to the stoppering machine, and then out to the collecting turntable. A crimping machine should be inserted after stoppering machine.
Automation of the entire process would convey an empty dose container from its supply carton through the entire process until it is filled with a product, labeled, and placed in the shipping carton.
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