- Author
- Persson, B. | Andersson, U. | Brandforsvar, G.
- Title
- Funktionsprovning av skuminblandningsutrustning. [Foam Proportioning Equipment.]
- Coporate
- Swedish National Testing and Research Institute, Boras, Sweden
- Report
- SP REPORT 1995:18, 1995, 54 p.
- Keywords
- foam extinguishing systems | fire tests | test methods | centrifugal pumps
- Abstract
- [ABSTRACT IN ENGLISH] A series of tests with various foam proportioning equipment has been conducted on behalf of the Swedish Fire Rescue Services Board. The aim has been to study their function at different working conditions, especially in combination with non-Newtonian liquids such as alcohol resistant foam concentrates. Five various in-line inductors, two around-the-pump inductors and three Essmixers were tested. All alcohol resistant foam concentrates on the Swedish market (P-marked) were used. The results show that there is a great need but also a great potential to improve foam proportioning equipment. A test method has been developed which allows to characterise the proportioning equipment without the need to consume foam concentrates. The teste of an inductor are conducted in two steps, firstly the suction characteristic is determined by the use of water instead of foam liquid. The suction pressure in the suction chamber in the inductor is determined as a function of the foam (water) flow rate. This gives a "suction characteristic curve" similar to flow/pressure curves for centrifugal pumps. In the second step of the test, the suction pressure determined in the first test is created in a vaccum tank. One end of the inductor is closed and the other connected to the vacuum tank and the flow rate of real foam concentrate through the inductor and its hose line is determined at various suction pressures. After each test the tank is emptied and after reconditioning the foam can be used again. This creates a second flow/pressure curve and the interconnection of these curves shows the induction rate achieved with a real foam concentrate in practical use. The tests show that various foam proportioning equipment has very different characteristics. On the basis of on the results it is also possible to judge the potential risk for miss function in different field conditions. The project also shows the problem to specify a viscosity value that correlates to the behavior in real equipment. The Brookfield method presently used by most foam manufacturers has shown not to be relevant. Further work on the correlation between viscosity properties and pipe flow for foam concentrates has therefore been conducted in a separate project.