JP2945988B2 - Membrane filter integrity test equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a membrane filter integrity test apparatus.

[0002]

2. Description of the Related Art Conventionally, various types of integrity test apparatuses for nondestructively testing a membrane filter are known.

For example, as a conventional membrane filter integrity test apparatus, there is a type in which a pressure rise curve is charted by a pen recorder, and operates in a bubble point mode and a pressure hold mode. In the bubble point mode, an arbitrary amount of gas is supplied from the primary side of the membrane filter, and the bubble point is read from a pressure rise chart. However, in the conventional apparatus, the bubble point occurs at a time point much lower than the time point specified by the filter manufacturer. The pressure rise curve differs depending on the gas supply amount from the primary side and the diffusion flow rate value of the filter. Therefore, it is very difficult to decipher the bubble points from the chart, and no validation is possible.

In the pressure hold mode, an arbitrary amount of gas is supplied from the primary side, and after the gas is pressurized to a specified pressure, the supply of gas from the primary side is stopped. After a certain equilibrium time, the state of the primary side pressure drop is output as a chart, which is read by the measurer. In this case, the state of the pressure drop is simply displayed in a chart, and no consideration is given to factors such as the volume and the temperature on the primary side. The measurer must take into account additional elements of the measurement line, but nonetheless cannot be correlated with the bacterial challenge test. Therefore, validation is not possible.

[0005] Further, a diffusion flow type integrity test apparatus to which a pressure hold test method is applied is known, and operates in each of bubble point, pressure hold, and diffusion flow test modes.

In the bubble point test mode, since the measurement is performed by a machine, the measurement error is lower than the measurement error by a human, but about ± 0.5 kg / cm 2 is still recognized. In addition, since the measuring method is different depending on the manufacturer, confusion is caused when a plurality of filter manufacturers are used. In addition, when performing validation by visual inspection while operating the integrity tester, it is a test mode in which bubble point validation should be performed exclusively for a disc-type filter because it is difficult for a cartridge-type filter to visually determine a bubble point.

[0007] The pressure hold test mode is
Although it is a mechanical measurement and the measurement error is extremely small, it is difficult to demonstrate the correlation with the bacterial challenge test submitted by the filter manufacturer itself, and it is not suitable for validation in the strict sense. Absent. This is because the pressure hold test mode method is greatly affected by the primary volume and the primary temperature of the filter under test.

In the conventional diffusion flow test mode, the diffusion flow rate is calculated from the primary volume measured by applying a constant pressure to the primary side of the measurement line and the pressure drop value using the above pressure hold test method. We ask, but there are problems in the following points.

A. The measurement method of maintaining the primary pressure at the specified pressure is not adopted.

B. The longer the equilibration time is, the more the measurement is performed from the specified pressure to a lower pressure.

C. When the temperature of the measurement line increases, gas expansion occurs, so that accurate measurement becomes impossible.

D. Although a function for mechanically calculating the volume of the primary side is provided as standard, there is a large error when measuring the volume. On the basis of this numerical value, the measurement error becomes large and the reproducibility is poor.

From the above viewpoint, this diffusion flow type integrity test apparatus also has a problem that the correlation with the bacterial challenge test is not obtained.

[0014]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for measuring a diffusion flow test at the time of preparing data for a bacterial challenge test, which is not affected by changes in the primary volume and temperature of the measurement line, and is not affected by the primary side. It is an object of the present invention to provide a membrane filter integrity test apparatus capable of detecting, measuring, monitoring, and recording the diffusion flow rate within a predetermined time with a very high accuracy while maintaining a constant pressure.

[0015]

In order to achieve this object, the present invention provides:
In a membrane filter integrity test device that tests the integrity of a membrane filter under test by sending fluid to the primary side of the membrane filter under test, a large flow rate capable of rapidly supplying a large amount of fluid to the primary side of the membrane filter When the pressure on the primary side of the membrane filter reaches a predetermined level by the mass flow controller and the fluid supplied by the mass flow controller, the operation of the mass flow controller is stopped, and at the same time, the small flow rate fluid is supplied to the membrane filter. A small flow rate controller for supplying to the primary side, a pressure detecting means for detecting a pressure on the primary side of the membrane filter under test and generating a detection signal, and a small flow rate corresponding to the value of the detection signal received from the pressure detecting means. Main controller for proportional / integral control of the controller Providing encompasses membrane filter integrity test system and.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to the drawings, a membrane filter integrity test apparatus according to the present invention comprises an inlet 10 for introducing a fluid used for a test, a safety valve 14 connected through a protective filter 12 connected to the inlet, and a safety valve 14 14 and a shut-off valve 16 connected thereto. Branch lines 18 and 20 are connected to the outlet side of the shut-off valve. One branch line 18 is provided with a small flow mass flow controller 22, and the other branch line 20 is provided with a large flow mass flow controller 24, which is located downstream of the large flow mass flow controller. Is provided with another shut-off valve 28.
These branch conduits 18 and 20 join at a junction 30 to form a discharge conduit 34 leading to an outlet 32. Immediately downstream of the junction 30, a pressure sensor 36 is connected to the discharge line 34. Further, on the further downstream side, a switching valve 38 is connected to the discharge line 34, and the switching valve 38 can shut off the discharge line 34 and connect the discharge port 40 to the outlet 32. ing.

The above movable parts are all provided by the main control means 4
2 is controlled. Accordingly, when fluid is supplied from the primary side of the filter casing and the filter element (including the disk type and the cartridge type), the internal pressure sensor 3 of the integrity test apparatus is supplied.
6 (capable of precise measurement of diffusion flow rate and measurement of minute pressure drop generated during diffusion), while measuring diffusion flow rate with high accuracy, the same is true in pressure hold test mode and bubble point test mode. The measurement can be performed with high accuracy, and the integrity of the system as well as the integrity of the filter itself can be confirmed.

When the membrane filter integrity tester is activated, pressure values are sampled every 10 seconds and stored in memory (Table 1 in FIG. 4). For example, on the basis of the Pn point, first, the sum of the preceding and following ΣP1 to ΣP4 is calculated, and Pn × ｛(ΣP2−ΣP1) / (ΣP4−ΣP
3) Find Pn 'from｝. The same calculation is repeated by sequentially increasing n to create Table 2 in FIG. Figures 2 and 3
According to the simulation graph of Table 2, Table 2
Is equal to the BP point (FIG. 2). Next, Pn '=-((ΣP2'-ΣP1') is calculated from Table 2 to create Table 3 in Table 4. Conversion from Table 2 to Table 3 is based on the data precision (resolution) of the actual machine. This has the effect of averaging the fluctuations that occur and prevents the table 3 from running out.The BP value is detected as a pressure value corresponding to the positive maximum value in the table 3, but in practice the table 3 is moved rightward by 5 points. It is searched after shifting (FIG. 3).

Another point to note is that the pressure rise is initially set at a supply flow rate of 0.1 bar / min.
Further, at the time of graph output, a negative value of Table 3 is not printed. Further, the 13 samples before and after the test are excluded from the range of the BP value because the data required before and after the calculation are not prepared. Furthermore, there are two conditions for terminating the BP test. (1) It ends when the maximum pressurizing pressure is reached. And (2) 0.004 for 10 seconds
When the pressure rise rate falls below the bar, the test is terminated after sampling 13 samples (the test starts at 0.016 bar / 10 seconds).

In the diffusion flow test mode, after the set pressure is reached, the output of the small flow rate controller always keeps the set pressure constant by proportional / integral control, so that the balance between the fluid supply amount and the diffusion flow rate can be adjusted with high precision. I can keep it. For example, for large filter housings or filters with high diffusion flow rates, increase the fluid supply,
For small capacity filter housings and filters with low diffusion rates, pressure can be maintained by reducing the fluid supply. In the proportional control, the difference between the set pressure and the current pressure is proportionally amplified to control the fluid supply amount. Integral control is
It serves to prevent oscillation (data disturbance) due to proportional control,
The control amount is averaged. By combining these two control methods, the fluid supply will eventually converge,
It becomes equal to the fluid diffusion flow rate value, and that value is output.

The point of the control method of this combination is as follows.
It is in the setting of each constant of proportional and integral. As a proof of this, various experiments were performed using different filter elements and housings (to examine the effect of the volume difference), and it was confirmed that stable data could be obtained regardless of the diffusion flow rate value and the change due to the volume difference. However, the larger the volume of the filter housing, the longer it takes to converge the fluid supply amount. Extremely large filter housings can be addressed by changing the mass flow controller to a larger one. The point is that the convergence is determined when the control amount changes within 1 cc / min with a change in the control amount of about 1 minute, and the design is designed so as to prevent the involvement of other electrical precision, so that the measurement error is extremely small.

Thus, this method eliminates the need for calculating or measuring the volume of the filter housing. The measured value is the absolute flow value (including system leak)
It can be measured as

In the bubble point test mode, similarly to the diffusion flow test mode, first, an appropriate amount of fluid is supplied by a large flow rate mass flow controller, and the pressure is increased by about 0.1 kg / cm 2 per minute. Control is performed to obtain an ascending curve. Based on this, at the time of the bubble point measurement, a fixed amount of fluid is supplied so as to perform a minute pressure rise regardless of the volume of the casing. When the bubble point is reached, the amount of fluid passing through the membrane rapidly increases, and the rate of pressure rise per unit time decreases. By sampling this series of changes and the pressure rise curve from the start to the end of the measurement at accurate time intervals, it is possible to calculate the change point of the pressure rise rate per unit time. It has been confirmed by theory and experiment that the pressure rise rate is completely proportional to time when a constant fluid amount is supplied to the primary side of the membrane filter by controlling the mass flow controller.

[0025]

According to the present invention, it is possible to obtain a membrane filter integrity test apparatus capable of verifying the integrity of a membrane filter with high accuracy in the diffusion flow test mode and the bubble point test mode.

[Brief description of the drawings]

FIG. 1 is a schematic view of a membrane filter integrity test apparatus according to the present invention.

FIG. 2 is a graph showing a change in a value by a membrane filter integrity test apparatus of the present invention.

FIG. 3 is a graph showing changes in values obtained by the membrane filter integrity test apparatus of the present invention.

FIG. 4 is a diagram illustrating a calculation method in the membrane filter integrity test apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Inlet 12 ... Protective filter 14 ... Safety valve 16 ... Shut-off valve 18 ... Branch line 20 ... Branch line 22 ... Small flow controller 24 ... Mass flow controller 26 ... shutoff valve 28 ... shutoff valve 30 ... junction 32 ... outlet 34 ... discharge line 36 ... pressure sensor 38 ... shutoff valve 40 ... discharge port 42 ・..Main control means

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-110445 (JP, A) JP-A 63-200748 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01N 15/08 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A membrane filter integrity test apparatus for testing a membrane filter under test by sending a fluid to a primary side of the membrane filter under test, wherein a large amount of fluid can be rapidly supplied to the primary side of the membrane filter. When the pressure on the primary side of the membrane filter reaches a predetermined level by the flow rate controller and the fluid supplied by the large flow rate controller, the operation of the large flow rate controller is stopped, and at the same time, the small flow rate fluid is fed to the primary side of the membrane filter. A small flow controller to supply,
Pressure detection means for detecting the pressure on the primary side of the membrane filter under test and generating a detection signal, and main control means for receiving a detection signal from the pressure detection means and performing proportional / integral control of the small flow rate controller in accordance with the value. And a membrane filter integrity test apparatus.