Inlet venting filters

All the gases that enter the chamber during the freeze-drying process of a parenteral product must be sterile [2.35]. This is attained by using hydrophobic inlet filters which are an integral part of the system and which are routinely sterilized together 

All the filters used must comply with the demands made by regulatory authorities. In sterilizable systems, hydrophobic diaphragm filters made of either polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE) with a diaphragm pore width of 

2 pm may be used. The filter elements are encased in stainless-steel casings which are resistant to pressure and temperature. 

The Parenteral Society [2.34] recommends the following criteria for integrity testing  

The test should be reproducible. Testing a filter under the same conditions should give the same results within the error margins inherent in the test. 

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Polyethylene, polystyrene, and PP fall under the classification of nonhydroscopic resins. These types of polymer resins collect moisture on the surface of the pellet only. The moisture can originate from several potential sources. Such moisture in some cases can be removed very easily by moderate preheating immediately prior to feeding the material into the mold. In some cases it is sufficient to provide vents at the transition from the hopper to the mold cavity. In some situations the moisture can be removed by passing warm air over the material. The equipment utilized to heat air and dry resins is usually very simple, e.g., an inlet air filter, a blower, and a controlled electric heater, as shown in Figure 47.11. 

The sterilization efficiency of the inlet venting Alters has to be assured by regular integrity tests. The filter integrity test should be performed automatically with the relevant data documented by the control system the principle is shown in Figure 20. The criteria for an integrity test given by the Parenteral Society [10] are summarized as ... 

Figure 20 Principle of a venting filter for in situ integrity tests. The integrity tests are carried out following the water intrusion method 1, primary filter with an 0.22 pm cartridge 2, secondary filter with an 0.22 pm cartridge installed as a backup filter, sterilized independently of the filter 1 3, test liquid reservoir (WFI) with heater 4, inlet valve for test liquid (WFI) 5, pure steam inlet 6, filtered air (5 bar absolute) 7, venting gas (1060 mbar) 8, drain line with valves 9, to water ring pump (WRP) 10, to condenser 11, to chamber 12, sanitary valves 13, temperature sensors.

Sterile Filtration of Gases. Primary appHcations for sterile gas filtration are the sterilization of fermentor inlet air, fermentor vent gas, vents on water for injection tanks, and vacuum break filters during lyophilization. Operational and process considerations apply. Typically, the membrane in gas... 

A 1-1. three-necked flask is equipped with a mercury-sealed stirrer, an inlet tube, and a reflux condenser which is connected through a soda-lime tube to a gas-absorption trap.1 The apparatus is dried in an oven and assembled rapidly to exclude moisture it is advisable to set up the apparatus in a hood to vent ammonia which may escape by accident. The flask is cooled in a Dry Ice-trichloroethylene bath, and 200 ml. of anhydrous (refrigeration grade) ammonia is introduced through the inlet tube from an ammonia cylinder which is either inverted or equipped with a siphon tube. Just before the apparatus is assembled, 8.1 g. (0.35 gram atom) of sodium is cut, weighed, and kept under kerosene in a small beaker. The Dry Ice bath is removed, the inlet tube is replaced by a rubber stopper, and a crystal of hydrated ferric nitrate (about 0.2 g.) is added. A small (about 5-mm.) cube of the sodium is cut, blotted rapidly with filter paper, and added quickly to the liquid ammonia. The solution is stirred until the blue color disappears, after which the remainder of the sodium is added in narrow, thin strips about as rapidly as... 

All the animation reactions are conducted in a 100-gal stainless steel reactor heated with 75 psi steam to the jacket. The reactor is fitted with an ammonia inlet, a vent tube for azeo-troping w from the system and a thermowell The TCTNB is first dissolved in toluene in a feed vessel and passed thru a 1.5 pm in-line filter during transfer to the reactor. The soln is then heated to 140° and the w azeotroped from the system. The ullage is then backfilled with ammonia and the temp brought to 150°. The... 

Powdered sodium tetrahydroborate(l -) (0.37 g, 0.01 mol) is added in three portions at about 30-min intervals to a suspension of dichlorobis(tri-isopropylphosphine)nickel (4.5 g, 0.01 mol) in diethyl ether (300 mL) and 95% ethanol (50 mL) in a 500-mL three-necked flask with an argon inlet and a gas bubbler vented to the hood. The reaction mixture is stirred with a magnetic stirring bar at 20° for approximately 5 hr. Gas evolution is observed, and the nickel complex dissolves gradually. After all the nickel compound is dissolved, the solution is filtered into a 500-mL two-necked flask and the solvent is removed under reduced pressure. The yellow residue is extracted with petroleum ether (200 mL), and the solution is washed with two 50-mL portions of water. The petroleum layer is separated, dried with 15 g of anhydrous sodium sulfate, which is washed with two 10-mL portions of the solvent which are added to the petroleum extract the combined extract is then filtered and concentrated in vacuo. The saturated solution (approximately 100 mL) is cooled to —78° in a Dry lce-2-propanol mixture overnight. The crystals which are formed are filtered, washed with a small amount (approximately 10 mL) of petroleum ether at 0°, and dried in vacuo to give brown crystals, mp 65-66° (decomposes). (Yield 2.5 g, 60%.) Anal. Calcd. for Cl8H43ClNiP2 C, 52.1 H, 10.4 Ni, 14.1. Found C, 52.3 H, 9.7 Ni, 14.1. 

The system vents through cartridge filters which are easy to replace. This system is used with multiple inlets and receiving points, for container unloading... 

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