Waterproofness Test Device for Rainwear

If you want to remain competitive, you have to keep pace with the market’s developments: Better accuracy, higher speed, greater functionality and lower price are typical demands. This often requires new, interdisciplinary competences when conventional methods are no longer sufficient. The following report shows that close cooperation with external specialists can fill these gaps when they are lacking internally.

Hydro Tester for Rainwear

Although not SI-conform, the term water column is widely used. For example, it can be found on the labels of breathable rainwear and functional clothing. It refers to the hydrostatic pressure that a fabric can stand against and is therefore the measuring of waterproofness. The corresponding unit, mWS (height of the water column in meters), is derived from the fact that a pressure is built up at the lower end of a water-filled cylinder (column) with the help of the weight force. In the classic test, the test object is attached there, for example a piece of tent fabric. The question in the leaking test is: At what height of the water column does the water begin to penetrate the test object? The corresponding pressure is an important measure in the textile industry.

Textest AG in Schwerzenbach has specialized in the development and worldwide distribution of measuring instruments for the textile industry for over 40 years. The latest product from Textest is the FX 3000 IV Hydro Tester, an instrument for measuring water tightness according to all important national and international standards. Of course, it does not work with an actual water column, but the measuring pressure is electronically controlled. In contrast to the previous models, the current instrument can run arbitrarily programmable pressure profiles and build up a maximum pressure of up to 5.0 bar (approx. 50 mWS). Other new features include a graphical user interface with color touch screen, USB and network connection, and data retrieval via an integrated web server. The instrument is also available in various versions and with various options, for example with an external compressed air connection, with integrated pump, with pneumatic sample pressure, with optional log printer, etc.

External Specialist Closes Competence Gap

Developing partner of Textest is the company Stettbacher Signal Processing AG. It is specialized in the planning and realization of challenging projects, especially in the fields of measurement technology, signal processing, machine controllers and drive technology, including the development and production of hard- and software.

The realization of the FX 3000 IV involved several challenges:

• The test pressure must be controlled precisely and continuously from 0 to 5000 mbar. The external compressed air connection, for example, feeds in considerable disturbance variables that the controller must suppress and correct.
• The device must measure several physical parameters very accurately and reproducibly. The measured values are digitally processed and prepared. The instrument can be calibrated and eliminates non-linear sensor behavior. This way, it meets the highest demands.
• The software for device drive system has been designed modularly so that it can integrate the numerous variants and options. The extensions and special functions can be configured via a special service menu on the graphical user interface.
• By using a pneumatic holding device for samples, the current standards and guidelines for machine safety come into play. Special procedures for personal safety had to be integrated so that, for example, one cannot pinch a finger when clamping a test object.
• The costs for the electronics and software had to be optimized while at the same time expanding the functionality. This was achieved in particular through well thought-out assembly and module planning. Various components can also be used unchanged in other Textest measurement systems.
• Great emphasis was placed on user-friendliness. Above all, the user guidance via the high-resolution color display should be so intuitive that even non-technical users can find their way around immediately (see picture). The sequence of a measurement is displayed in a graphically appealing manner. For the international market, the instrument is equipped with eight languages, including Chinese and Japanese.
• The problem for the user is that it can take several hours for the first drops of water to get to the test object and to complete the leaking measurement. So, someone has to monitor the process and wait for the first drops. To optimize this process, an automatic optical drop detection system was implemented, based on the O-3000 camera from Stettbacher Signal Processing. It reliably locates and counts water drops and completes the measurement accordingly.

From a technical point of view, the device is based on a low-cost embedded PC that runs Linux. So, many useful network services are available for free and in first-class quality. The operating system has been reduced to the essentials, so that it gets by with modest resources. An FPGA is used as the front end to the measuring systems and actuators, which automatically takes over numerous machine-related functions.

With ,,drop detection’’ no one is left standing in the rain!

Stettbacher Signal Processing AG was able to systematically master the challenges and successfully complete the order. Among other things, this resulted in the globally unique drop detection system, which allows fully automatic leakage measurements to be carried out. As is often the case with such developments, new wishes and requirements were added during the project. This is important and reasonable but requires a great deal of flexibility and foresight in planning and realization. The most important success factor in this process is the constant communication between all partners and in all project phases. This resulted in a product that stands out due to its excellent range of functions, its compactness and its high level of user-friendliness.