The design and operational reliability of bathroom fittings or shower heads are rather important factors as far as the consumer is concerned. In particular, these components must run smoothly even if the water supply is sometimes irregular. Abrupt changes in temperature or pressure in the cold and hot water supply can be uncomfortable at best, possibly harmful at worst, which is why reputable manufacturers subject their products to extensive and precise quality tests before they ever reach the market.
One such manufacturer is the Alpharetta, USA based Hansgrohe Inc, which recently appointed the German test rig technology specialist, measX to equip a purpose-built test stand, including the software and all necessary measurement hardware. The measurement system provides standardised and user-friendly test programs that the user can adapt according to the hardware under test and whichever test routine is selected. The software architecture also includes a diagnosis mode for function checks and error searches of the test stand.
The measurement computer is based on two National Instruments (NI) NI-PC I-6024 boards, which acquire analogue measurement values such as temperature, pressure and flow rate, as well as controlling the speed of the water pumps. In addition, two NI-PC I-6527 boards are used to handle the test system’s digital I/O. Altogether, the system comprises 16 analogue inputs (connected differentially), 4 analogue outputs and 48 optically isolated digital inputs and outputs.
The measurement program was developed using NI’s DASYLab, which is supported in the UK by Adept Scientific. This easy-to-use software for data acquisition, data control, data analysis and data presentation comprises four components: a main menu, a diagnostic mode, a manual mode and a sequential mode.
The main menu covers a host of general functions, and allows the user to select the test procedure with a simple mouse click. In diagnostic mode the user can separately access and display each input and output, check the system operation and conduct an error search – a very useful feature when dealing with complex test rigs.
In manual mode the user can set up individual test procedures, operate the supply pumps and valves, and choose between the two operating modes for pressure control. The program provides various numeric or graphic status display options for the test rig and test results, and allows new sensors to be integrated with the minimum of effort.
Sequential mode allows the tests to be conducted in two ways: manual pressure control or pressure control via the variable speed pumps. In both modes the user is able to simulate warm water pressure decrease; warm water pressure increase; cold water decrease; cold water increase; warm water pressure loss; warm water temperature change, and cold water pressure loss.
To run these tests, the user has only to enter parameters such as cold water pressure before and after the pressure loss. The program controls the pumps and valves automatically, thus protecting the system from operator error. The test does not start until the user enables the system from the control panel, and all measurement values are subsequently saved to disk for later evaluation.
This DASYLab application offers a number of advantages for this application, including easy simulation of water supply volume changes, a choice of manual or automatic control of the test stand functions and easy configuration of complex measurement profiles. Additionally, the software provides powerful diagnostics on each measurement channel, a sensor calibration capability and full data archiving for later report generation and test data analysis.
But performance and stability were not the only design priorities when MeasX set about creating this system for Hansgrohe. User friendliness was also deemed essential, and thanks to DASYLab’s graphical interfaces, the user does not need special programming skills in order to run these quality control tests.