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Advantages of Smart Proportioning Systems

As practiced for decades in fire protection systems, the procedure to check the proper functionality of foam extinguishing systems includes an annual check of the proportioning rate. This check can be done by measuring the conductivity of a foam solution sample or - in case of water-driven variable viscosity foam proportioners – by simultaneously but separately measuring the discharged volume flows of extinguishing water and foam agent.

Based on the measured flow rates, the proportioning rate can be calculated according to a formula defined in national and international standards instead of generating a foam-water solution. The results are usually documented in a handwritten maintenance log. 

This procedure is potentially prone to human error.

The impact of such errors can go in both directions - a too low or too high proportioning rate with the associated consequences for the poor extinguishing performance of the foam or the shortening of the extinguishing time due to excessive consumption of the foam agent.

GEN III proportioners from FireDos offer optional remote monitoring. 

Checking the proportioning rate of mechanical FireDos proportioners                                      

In addition to the regular proportioning mode, FireDos proportioners can be operated in a testing mode, so that there is no production of any water-foam solution (premix) needed for checking the proportioning rate. During regular operating mode, the water flow of the firewater pump drives the water motor of the proportioner. This in turn drives the proportioning pump, which draws the foam agent from the foam agent tank and feeds it into the extinguishing water flow.

Once the proportioner is set to return/test mode, the foam agent discharged by the proportioning pump is no longer delivered to the extinguishing water but is recirculated to the foam agent tank via the so-called ‘return line’. That way, the system is tested with using foam agent but without consuming it. To establish realistic test conditions in the return line, a dedicated valve is simulating the operating water pressure of the extinguishing system 

After the proportioner has reached the anticipated extinguishing water test flow rate(s), the foam agent flow rate in the return line and the water flow rate are measured simultaneously by separate volumetric flow meters.

Based on these data, the proportioning rate can be calculated according to the formula below which is in accordance with the international standards EN 13565-1, NFPA 11, FM 4-12 and the formula specified in the Nordtest method NT Fire 042: 

Foam agent flow rate [GPM]
---------------------------------------------------------------------- x 100 = Proportioning rate %
(water flow rate + foam agent flow rate) [GPM] 

Potential errors during proportioning rate testing

Although this test method is much more accurate and reliable than measuring the physical properties of a premix sample, it still carries a certain residual risk of human error. Reading, calculation or writing errors can lead to the documentation of incorrect proportioning rates. 

This is where FireDos comes into play with their monitoring system for proportioners, with the goal of supporting operators in their maintenance and testing tasks.

Smart versus mechanical proportioner – Contradiction or useful addition?

Smart proportioners are generally an intelligent upgrade to mechanical foam proportioners. This upgrade adds many different functions and fulfills many diverse tasks. The monitoring system for proportioners is just one of them. The operating principle of the proportioner as such, which has proven itself in thousands of systems over the last 3 decades, is not changed and remains purely mechanical. 

Proportioning rate testing the smart way

The monitoring system includes sensors, a control unit and an optional display unit. It controls the automatic measurement, displaying and recording of operating parameters of the proportioner. 

The smart proportioner comes with volumetric flow meters installed in the foam agent return line and the extinguishing water line. 

The continuous measurement of the foam agent flow rate in test mode and the water flow rate through the water motor makes the calculation of the proportioning rate as easy as possible. 

In addition, the control system records all sensor data in a log file, processes it and displays it to the operator on request. An integrated wireless network interface enables communication between the display and a smartphone, tablet or notebook. 

Functionality and features of the monitoring system

The design of the basic version comprises three core components. 

  • Measurement of the foam agent flow rate:
    By standard, the foam agent flow rate is measured with a volumetric flow meter in the foam agent return line. Optionally, it can also be measured in the proportioning line. This enables the measurement even during the extinguishing process, means when actual proportioning to the extinguishing water is happening.

  • Measurement of the water flow rate:
    By standard, the water flow rate is normally measured with the FireDos volumetric flow meter but can also be measured with any other existing volumetric flow meter.

  • The control unit:
    Records and processes the transmitted sensor data. In addition to operating parameters, it determines the proportioning rate. All data are saved in a log file.

    As an option, the control unit can be equipped with an integrated display and/or a wireless interface.

    To check the proportioning rate, the proportioner is usually set to return/test mode and operated as described above. As the control unit records the respective water and foam agent flow rates, it calculates the proportioning rate accurately based on this measurement data. All this data is saved in a log file at regular intervals and can be shown on the optional display.

    Alternatively, and if there is a volumetric flow meter installed in the proportioning line, the proportioning rate can also be monitored in proportioning mode during extinguishing process.

    If the unit is equipped with the optional display, the parameters will be shown as below. 

Smart proportioning in an extinguishing system

FireDos has developed and built a model system to investigate the practicality of a monitoring system and to generate data for evaluation. 

The prototype is a miniaturization of a foam extinguishing system, consisting of an open sprinkler system paired with a firefighting monitor. In addition to the foam discharge devices, there is a water tank, a foam agent tank, a water pump, and a FireDos proportioner of the latest generation GEN III with the water flow meter based on revolution counting. This is the standard equipment for measuring the water flow rate on FireDos proportioners. 

What are the advantages of a monitoring system for foam proportioners?

Smart proportioners offer specific advantages to operators and users of extinguishing systems, as they provide added value in the inspection and maintenance of foam extinguishing systems which ultimately benefits overall functionality. 

  • Correct proportioning rate determination:
    The proportioning rate as the most crucial parameter when testing proportioners, is always calculated correctly by the embedded algorithm. This excludes any possible calculation errors, allowing flawless checking of the proportioner's functionality. The proportioning rate calculation is conducted in accordance with all above/mentioned standards.

  • Documentation and maintenance date monitoring:
    The date of the maintenance and the proportioning rate data are recorded. On request, a reminder can be sent for the next due maintenance date.

  • Permanent proportioning rate measurement:
    Water-driven foam proportioners are variable flow devices with a huge operating flow rate range. With the ‘Smart’ version, the proportioning rate is measured permanently and across the entire operating range fully automatically.

  • Usage documentation:
    An optional volumetric flow meter in the proportioning line allows measuring the total consumption of foam agent and extinguishing water during proportioning operation, i.e., in case of a fire. This helps to provide evidence about discharged quantities of extinguishing agent towards third parties like authorities, etc.

  • Determining additional operating parameters:
    In addition to the proportioning rate and operating data, other parameters can be collected such as the foam agent temperature, the oil level in the proportioning pump, the ball valve positions in case of an existing position indication, and operating times and hours. Operating hours serve also as an indicator for the maintenance interval of the proportioner.

  • Visualization of proportioning rate and parameters:
    All above/mentioned operating parameters and recorded data proportioner are displayed locally. The connection can be made via a wireless network interface on any smartphone, tablet or notebook. Optionally, a local display is possible. Remote visualization is also possible as an option.

  • Recording of all operating parameters:
    The proportioning rate and all other measured operating parameters and data are permanently recorded with a timestamp at defined intervals. This creates a history of the operation, conducted tests and maintenance of the proportioner.

  • Remote diagnostics:
    The monitoring system allows remote diagnostics, even if there is no direct remote access to the control unit. Initial basic diagnostics can be carried out remotely using images from the display or by means of a video call with little effort.

  • Saving costs:
    The feature of remote diagnostics reduces on-site service efforts and the costs associated with the visit from a FireDos authorized service technician. 

Conclusion and perspective

Maintaining the functionality of foam extinguishing systems requires the proportioning rate of proportioners to be checked at fixed intervals. With the monitoring system for its proportioners, FireDos offers a major improvement on previous practice by eliminating possible errors. It guarantees correct evaluation and recording of the proportioning rate and supports the system owner in the monitoring of maintenance dates. In addition, the ‘Smart’ system opens up new possibilities for remote diagnostics and helps to reduce service costs. 

Smart proportioners are an intelligent electronic upgrade to mechanical proportioners. This technology takes the functionality and reliability of mechanical FireDos proportioners to the next level in any foam-based fire protection system. 

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