Translation of "Druckhaltetest" in English

This can be verified with a conventional pressure-holding test.

P is greater than the duration of treatment, the cyclic pressure-holding test can be dispensed with.

For the pressure-hold test, pressure is applied to the wetted membrane.

The tightness of the balancing circle may be tested by using a pressurizing test (DHT).

Such a test is known as a pressure maintenance test or pressurizing test.

The dialysis liquid circuit is then stopped for the pressure holding test.

The pressure resistance test checks the functionality of the membrane.

Consequently, this pressure retaining test first provides an indication of a defect in the entire balancing system or at the sterile filter.

For the pressure holding test, the filter is slowly acted upon on one side with a pressure and the liquid displaced.

These valves which are switched in alternation permit a pressure-holding test even while dialysis fluid is flowing through the dialyzer.

Initiation of the pressure-holding test can be made dependent upon various criteria, for example, only when there is a positive dialysis fluid pressure.

However, the pressure-holding test can also be performed before or after the saline rinsing process before the blood treatment.

This method has proven useful in practice but has the disadvantage that the dialysis treatment has to be interrupted at regular intervals for the pressure-holding test.

For this purpose, when the predetermined limit value is exceeded, the blood treatment is interrupted and the pressure-holding test is carried out with the appropriate sensitivity.

However, if the pressure-holding test does not reveal any loss of leaktightness, monitoring of the fluid system on the basis of the continuous pressure measurement is preferably reinitiated.

This pressure-holding test for detecting a leakage is described in detail in German Patent Application No. 42 39 937 A1, which is incorporated by reference herein.

To check the dialysis fluid system I for loss of leaktightness, the dialysis apparatus has a means 25 with which a pressure-holding test can be carried out.

However, the possible loss of leaktightness of the system is preferably verified by the means 25 which carries out the conventional pressure-holding test.

When embedding hydrophilic filter membranes, such as, e.g. nylon membranes, into hydrophobic retaining elements, such as, e.g., end caps out of polypropylene, polysulfone or polyethylene, the membrane filter edges are hydrophobized beyond the embedding region, so that this edge region, that is no longer wettable by water, contains a large number of pores which, when subjected to the bubble-point test or the pressure resistance test (integral test) of, for example, the filter cartridge, represent an air by-pass, thus making it impossible to test the filter cartridge.

By means of air diffusion measuring (resistance test or integral test) the wetting of these filter cartridges was then tested under the below conditions after each wetting:

A retaining test can then be carried out on the apparatus thus prepared and this makes it possible to check the intactness of the fluid balancing system of the apparatus and of the sterile filter.

In contrast, in the pressure retaining test a partial vacuum is generated which permits the entry of air through the pores of the flexible tube.

In this pressure retaining test fluid is withdrawn from the closed circuit with the aid of the ultrafiltrate pump and said fluid is first expelled from the bypass part by the simultaneously supplied air.

BACKGROUND OF THE INVENTION In filter testing, filters are subjected to a so-called pressure-resisting test at a predetermined pressure by a testing device.

In case that a membrane integrity test conducted automatically by the system or manually (for example, a pressure-maintaining test such as integrated, or differential pressure measurements, or dosage of particles in the inflow and particle counting or turbidity measurements or others) shows that the membrane is defective or does no longer satisfy the required retention performance for particles, bacteria, viruses, parasites or other contaminants, the unit may ensure that water potentially contaminated with microbes cannot reach the drinking or service water network through the defective filters.

As an alternative, it may also be possible to apply a vacuum to the fluid port 53 of the outer pipe 3 (e.g., when using a fluid connection under negative pressure conditions) and/or a direct connection with the drain that is open to the atmosphere (e.g., when using a fluid connection under overpressure conditions) and to perform a pressure keeping test of the inner fluid connection—in particular between inner pipe 1 and connection pipe 5 —on behalf of the self-check routine.

Such examination may, for example, be an air pressure test which may simply and easily be performed by opening the valve device of the invention, pressing a test fluid into a compressible space against the direction that is possible in conventional check valves, and then bringing the valve device of the invention into a check valve position.

In this arrangement, it is advantageous that a pressure test performed in a connected fluid circuit does not cause any damage to the hydrophobic membrane.

Such a state arises, for example, when the dialyzer is bridged by a bypass as part of a pressure holding test.