Insulator with venting arrangement and method for venting the working area of an insulator

Abstract

In an isolator with a working area and with a ventilation arrangement which has a pressure monitoring circuit which, during use, automatically detects the internal pressure (pi) prevailing in the working area and compares it with a target pressure, and automatically raises the internal pressure (pi) to at least the target value if the target pressure is undershot, the invention proposes that the ventilation arrangement has a compressed air reservoir connected to the working area, in which a reservoir pressure prevails which is at least as high as the target pressure of the working area, wherein an air line runs from the compressed air reservoir to the working area, which air can be selectively interrupted or flowed through by means of a check valve, and that the pressure monitoring circuit is designed in such a way that the check valve is automatically opened if the target pressure is undershot.

Description

[0001] The invention relates to an isolator according to the preamble of claim 1 and a method for ventilating the working area of such an isolator.

[0002] Such isolators are used in the pharmaceutical sector, although depending on their design, some are also referred to as "large-capacity isolators" in practice. A "large-capacity isolator," for example, is large enough to accommodate people, e.g., for maintenance purposes and to install equipment used for fully automated handling of the pharmaceutical product (feeding, filling, and removing it from the isolator). Smaller isolators are used, for example, for small batches and for testing purposes, e.g., during the trial phase of the pharmaceutical product. They are not fully automated and have, for example, reach-through openings for gloves, so that the aforementioned handling of the pharmaceutical product can be carried out manually, with the personnel outside the isolator.

[0003] A generic isolator used for work in the pharmaceutical industry, as well as a method for ventilating its work area, are known from practice. In a work area of the isolator, also referred to as a production room, there is an internal pressure that is regulated by the supply and exhaust air volume flows of the so-called working air, namely the air used to ventilate the work area. The supply and exhaust air volume flows are regulated in a technical area of the isolator by the supply air in a suction plenum and the exhaust air extraction in a pressure plenum. The supply and exhaust air units used in this isolator, which is known from practice, are designed as independent filter systems with their own drives.They ensure the air exchange rate in the work area, which is flowed through by the working air from top to bottom, and return the air volume lost through the isolator openings to the work area. The internal pressure in the work area is measured below the air outlet surface and differentiated from the neighboring sections and surrounding rooms. A differential pressure of 10-15 Pa (guideline value) is maintained.

[0004] The internal pressure is regulated by controlling the exhaust air unit, e.g. the exhaust air fan and an exhaust air damper, and thus by adjusting the volume of air to be discharged. For this purpose, the isolator has a ventilation arrangement which, among other things, contains a pressure monitoring circuit by means of which the internal pressure in the working area is automatically and practically continuously recorded and compared with a reference pressure. For example, the recorded internal pressure can be compared with the target pressure or with a lower limit of a pressure which must not be undercut and which can be referred to as the limit pressure. If the target pressure is undercut by a certain amount, namely when a so-called alarm pressure is reached when approaching the limit pressure, the pressure monitoring circuit causes the internal pressure to be automatically raised to at least the target value, thus preventing a pressure drop to the limit pressure.

[0005] An unacceptably large deviation from the reference pressure therefore means that when comparing the internal pressure with the target pressure, the two pressure values differ significantly. When comparing the internal pressure with the limit pressure, however, the two pressure values should differ significantly, so in this case, the unacceptable deviation occurs when the deviation between the two pressure values, the internal pressure and the limit pressure, is too small.

[0006] Severe pressure fluctuations are prevented during normal operation by the employees' standard operating procedures (SOPs). For example, slow movements by employees are required, including the use of gloves during the process and when inserting or removing isolator openings to a surrounding room or neighboring sections. However, it cannot be ruled out that severe pressure fluctuations may occur due to human error or excessively rapid movements, resulting in an internal pressure in the work area that deviates from the specified target value. In some cases, the pressure may even fall below the limit pressure, meaning that the basic requirements for a GMP-compliant process cannot be met and the isolator loses its production approval.

[0007] If this condition of pressure below the limit persists for more than 5 seconds, the isolator loses its aseptic status and is considered no longer suitable for production. This is economically disadvantageous: in addition to the costs of production downtime and the lost material, there are the costs of extensive cleaning to restore the aseptic status and resume production.

[0008] The invention is based on the object of improving a generic isolator such that it ensures the maintenance of a predetermined internal pressure in the working area as reliably as possible, in particular enabling the restoration of the predetermined internal pressure as quickly as possible in the event of a pressure drop. Furthermore, the invention is based on the object of providing a method for ventilating the working area with the aforementioned advantages.

[0009] This object is achieved by an insulator having the features of claim 1 and by a method according to claim 7. Advantageous embodiments are described in the subclaims.

[0010] In other words, the invention proposes that, in the event of a pressure drop, pressure equalization be achieved by introducing a sufficiently pressurized volume of air into the work area. The invention is based on the consideration that, while influencing the working air blower units is fundamentally suitable for setting the desired internal pressure in the work area, the response behavior of a blower unit is too slow to achieve the desired pressure equalization within the shortest possible time. Instead, the ventilation arrangement according to the invention has a compressed air reservoir so that a specific volume of air is constantly available. The pressure level within the compressed air reservoir is at least as high as the target pressure of the work area.If the internal pressure in the working area drops unacceptably far below the target pressure, namely to an alarm pressure, air can flow from the compressed air reservoir into the working area, preventing a further pressure drop to the limit pressure. For this purpose, the compressed air reservoir is connected to the working area via an air line. According to the invention, this air line can be opened or closed as required using a shut-off valve.

[0011] During normal operation, the air line is blocked, i.e., interrupted, by the shut-off valve. However, if the internal pressure in the work area drops below the aforementioned alarm pressure, the pressure monitoring circuit automatically opens the shut-off valve, allowing the stored compressed air to flow through the air line from the compressed air reservoir into the work area with virtually no delay, increasing the internal pressure prevailing there. The switching process to open the shut-off valve can take place in a considerably shorter time than an equally effective change in the fan speed, so that the inventive design of the ventilation arrangement allows a considerably faster change in the pressure conditions.It can therefore be assumed that an inadmissibly prolonged undershoot of the limit pressure by such a degree that it would lead to a loss of aseptic status can be reliably prevented in practice for almost all common pressure fluctuations. The short reaction time enabled by the invention can even prevent a pressure drop to the limit pressure altogether, so that the pressure is not only not undershot for a certain period of time, but is never even reached.

[0012] The pressure monitoring circuit can be designed in the form of an electronic control system to which one or more sensors and actuators can be connected, for example pressure sensors and actuators for opening or closing valves. The internal pressure in the working area is monitored practically continuously, e.g. detected by sensors and compared with the target pressure, namely several times per second, e.g. at intervals of 3 to 5 ms. As an alternative to an electronic control system, the pressure monitoring can also be managed by a number of separate elements which do not have to be interconnected by a common control system, but which rather each act independently, e.g. in the form of valves which switch automatically depending on the pressure, for example changing their switching position when a certain pressure level is exceeded or undershot, e.g. opening to different widths or automatically opening or closing completely.close completely automatically.

[0013] In one embodiment, a pressure monitoring circuit is also assigned to the compressed air reservoir. This can be the pressure monitoring circuit of the isolator or a separate pressure monitoring circuit assigned exclusively to the compressed air reservoir. The so-called reservoir pressure prevailing in the compressed air reservoir is automatically monitored by this pressure monitoring circuit, and if the reservoir pressure drops, the pressure within the compressed air reservoir is automatically increased to a predetermined target reservoir pressure. This can be achieved, for example, by means of a pressure control valve, which allows compressed air to flow from a compressor or from another, higher-level compressed air reservoir into the compressed air reservoir of the isolator's ventilation system as needed.The pressure monitoring circuit of the compressed air reservoir works in such a way that the compressed air reservoir is filled with compressed air upon initial start-up until a predetermined reservoir pressure is reached inside the compressed air reservoir. The compressed air reservoir is then automatically refilled with compressed air at regular intervals when the pressure level drops below a predetermined threshold. This can occur due to losses in the form of leaks or because the compressed air reservoir has released compressed air into the isolator's working area.

[0014] In one embodiment, a solenoid valve is used as a shut-off valve, which selectively opens or closes the air line between the compressed air reservoir and the work area. This enables rapid response and thus short reaction times of the ventilation system to a pressure drop in the work area, since the solenoid valve changes its switching state in the single-digit millisecond range. Furthermore, the use of a solenoid valve allows the shut-off valve to be controlled by an electronic control of the pressure monitoring circuit.

[0015] The volume of working air contained in the work area depends on the size of the work area. To compensate for a pressure drop as quickly as possible, a correspondingly large air volume must be provided in compressed air reservoirs. An economically advantageous option for adapting the ventilation arrangement to the different sized work areas of different isolators is to provide the total volume of stored compressed air not in one, but, if necessary, in two or more compressed air reservoirs. In this way, the ventilation arrangement can be easily scaled without the need to provide compressed air reservoirs of different sizes, each requiring its own type approval.

[0016] In order to keep the reaction time as short as possible in the event of a pressure drop in the work area, two or more compressed air storage units can be used so that a correspondingly large amount of stored compressed air can be fed into the work area at a comparatively high pressure level.

[0017] Finally, even in cases where a single compressed air reservoir is sufficient to equalize the internal pressure prevailing in the work area, the isolator's ventilation arrangement can incorporate two or more compressed air reservoirs. This allows the stored compressed air to maintain the desired internal pressure level in the work area even in the rare cases where the internal pressure drops in quick succession. This way, the second compressed air reservoir provides sufficient time to ensure safe operation of the isolator until the first, empty compressed air reservoir is refilled and ready for use.

[0018] If more than one compressed air reservoir is used, these can be connected to a common air line. In one embodiment, however, the compressed air reservoirs are each connected to the work area via their own air line. This also shortens the response time for compensating a pressure drop in the work area, because it supports the flow of the largest possible amount of compressed air at the highest possible pressure level into the work area.

[0019] The invention is explained in more detail below based on the functioning of a ventilation arrangement of an insulator according to the invention. Fig. 1 shows the temporal progression of the internal pressure in the working area of an isolator with pressure conditions shown purely as examples.

[0020] Fig. 1 shows a diagram in which the course of a pressure p is plotted against time t. An upper line with different pressure values represents an internal pressure pi prevailing in the working area of an isolator. Below this, a horizontal line with a constant pressure value indicates a defined limit pressure pg, which must not normally be undercut inside the working area. In the example shown, the overpressure in Pa is plotted on the vertical axis, which prevails in the working area compared to rooms adjacent to the working area. Accordingly, in the example shown, the internal pressure pi in the working area should not fall below a limit of 15 Pa, and the target value of the internal pressure during normal operation is around 26 to 30 Pa.

[0021] Sudden pressure fluctuations occurring in the working area can in practice be so great that the limit pressure pg would be undershot. In such exceptional cases, it must be ensured that the undershoot of the limit pressure pg does not exceed a specified period of time and, ideally, a pressure drop down to the limit pressure pg can even be completely avoided. The internal pressure pi prevailing in the working area is monitored almost continuously by means of a pressure monitoring circuit, for example by pressure measurements at intervals of 3 ms. If the pressure falls below an alarm pressure pa that is higher than the limit pressure pg, an error signal is automatically generated.

[0022] In the example shown, a compressed air reservoir is assigned to the working area. The pressure monitoring circuit compares the actual internal pressure pi with a reference pressure, for example, with a specific target pressure or with the alarm pressure pa, which in the example shown is 20 Pa. The first in Fig. 1 The pressure drop shown occurring at time t 1 is so short-term that its deviation from the target pressure is so slight that the internal pressure pi does not drop to the alarm pressure pa. However, the pressure drop occurring shortly thereafter at time t 2 deviates so greatly from the target pressure that the internal pressure pi drops below the alarm pressure pa.

[0023] When the alarm pressure pa is undershot, the pressure monitoring circuit automatically activates a solenoid valve, which opens an air line leading from the aforementioned compressed air reservoir to the work area. Within a very short reaction time of, for example, approximately 8 ms, the air line is opened, and compressed air can flow from the compressed air reservoir into the work area. Accordingly, as shown in Fig. 1 As can be seen, the internal pressure pi only continues to decrease slightly after reaching the alarm pressure pa and does not drop to the limit pressure pg. Rather, there is a rapid pressure increase up to a maximum value of 38 Pa at time t 3 , when the compressed air reservoir is almost completely empty. From time t 3 onwards, the internal pressure pi then drops back into the range of the setpoint, since the internal pressure is regulated back into the setpoint range by means of the ventilation arrangement.

[0024] The air line is now automatically closed again by means of the solenoid valve, so that the compressed air reservoir can then be automatically refilled via a pressure control valve and is ready for the next use. Reference symbol:

[0025] pi Internal pressure pa Alarm pressure pg Limit pressure t 1 Time of first pressure drop t 2 Time of second pressure drop t 3 Time of pressure maximum

Claims

1. Isolator, • with a working area in which a predetermined internal pressure p corresponding to a target pressure i prevails, • a supply air area, from which working air flows into the work area during use, • an exhaust air area, into which the working air flows out of the work area during use, and with a ventilation arrangement which has the following elements: • filter units which are arranged in the supply air area and / or in the exhaust air area and through which the working air flows during use, • at least one blower unit which sets the working air in flow during use, • and a pressure monitoring circuit which is designed in such a way that ∘ the internal pressure prevailing in the work area (p i ) is automatically recorded and compared with a reference pressure ∘ and in case of an inadmissibly large deviation from the reference pressure, the internal pressure (p i ) is automatically raised to at least the target pressure, characterized by that the ventilation arrangement comprises a compressed air reservoir in which a reservoir pressure prevails which is at least as high as the target pressure of the working area, wherein the compressed air reservoir is connected to the working area in such a way that an air line runs from the compressed air reservoir to the working area, wherein the air line can be selectively interrupted or flowed through by means of a shut-off valve, and that the pressure monitoring circuit is designed in such a way that the shut-off valve is automatically opened in the event of an unacceptably large deviation from the reference pressure.

2. Insulator according to claim 1, characterized by that a pressure monitoring circuit is assigned to the compressed air reservoir, which is designed in such a way that the reservoir pressure prevailing in the compressed air reservoir is automatically monitored and, in the event of a pressure drop, the pressure within the compressed air reservoir is automatically increased to a predetermined target reservoir pressure.

3. Insulator according to claim 1 or 2, characterized by that the pressure monitoring circuit assigned to the compressed air reservoir has a pressure control valve.

4. Insulator according to one of the preceding claims, characterized by that the shut-off valve arranged in the air line is designed as a solenoid valve.

5. Insulator according to one of the preceding claims, characterized by that several compressed air storage units are connected to the work area.

6. Insulator according to claim 5, characterized by that the compressed air storage units are each connected to the work area via their own air line.

7. A method for ventilating the working area of an isolator, wherein working air is supplied from outside to the working area and is led out of the working area to the outside, and wherein within the working area an internal pressure p idesignated air pressure is built up, which corresponds to a certain target pressure, and whereby the internal pressure p i above a certain limit pressure p g maintained by increasing the amount of air supplied to the working area when the internal pressure p i a specific alarm pressure p a which is below the internal pressure p i and above the limit pressure p g lies, characterized by that compressed air is provided in a compressed air reservoir which is at a storage pressure prevailing in the compressed air reservoir that is at least as high as the target pressure of the working area, and that To increase the amount of air supplied to the work area, a shut-off valve is opened in such a way that air now flows from the compressed air reservoir through an air line into the work area.

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