Like our previous waterbath machines, the new generation combines the advantages of both dry and wet testing. There are typically three modes of operation which are easily selected using a selector switch, mounted on the control panel. Recent machines we have supplied use an industrial PC which acts as the HMI and offers powerful data collection facilities. It also allows the machine to be connected to any factory network for remote access if required.

Principle of Operation

The part is loaded by the operator onto the fixture. When the test is started, the part under test is clamped and sealed automatically using pneumatic cylinders. The Leak Test is carried out with use of a Mass Flow Meter which monitors the air flow into the part. During the fill part of the sequence, the Mass Flow Meter is bypassed to allow the part to be pressurised quickly to the desired test pressure. The Flow Meter is then switched into the circuit and if the part has no leak, air flow into the part will cease.

Wet Test Only - When the machine is set to this mode, the part is pressurised and then automatically immersed once the required test pressure has been achieved. This then allows the operator to check the part visually for leaks and repair if necessary.

Wet and Dry Test - When set to this mode, the machine will first carry out a 'Dry' test and if the leak rate of the part under test is below the desired leak rate, the part will be released at the end of the test to allow the operator to remove it. However, if the dry test identifies a leak, the part is automatically immersed to allow the operator to check the part visually.

Dry Test Only - When set to this mode, the machine will carry out a dry test only and regardless of the result, the part is not immersed.

The Water System

As explained earlier, upon a failure the part under test is automatically submersed in water to allow the operator to visually locate the leak.

The technique used to do this has no moving parts so is very reliable and robust. Within the main water tank is another upturned tank. To raise the water the upturned tank is purged with compressed air which displaces the water in the main tank, therefore raising the water level to cover the part. The height the water ultimately reaches is easily adjustable using a pressure regulator. To lower the water, the air is dumped from the upturned tank.

The picture on the right shows the machine with no fixture fitted and the water beginning to rise.

The water system is self cleaning and this is done by using a weir. When the water rises some will overflow into the weir. This water is then automatically pumped back into the main tank through filters to remove any contamination.

The water level in the tank will reduce over time through both evaporation and the fact that a certain amount is carried out of the tank on the parts tested. This level is automatically maintained using level sensors and valves to fill/empty water to maintain the correct level.

It can be seen from the picture on the left that high intensity lights will illuminate when the water is raised. This makes the locating the leaks much easier for the operator.