Regular testing and maintenance ensure a maximum service life and functional and failure-related safety of technical appliances. The same applies to foam-based fire extinguishing systems and the foam proportioners installed in them.
Up to now, such testing and maintenance have required the presence of personnel on-site. However, it would be easier and more cost-efficient for extinguishing system operators if this was possible in a fully automatic and remote-controlled manner. For example, this would also make regular maintenance personnel travel to remotely located proportioners redundant. In addition, this would ensure that requirements by the manufacturer, standards and sets of regulations are observed without any functional deviations and unsuitable time intervals.
The remote testing system within the ‘Smart Proportioner’ development framework has been created just for this purpose. It is an advancement of the remote monitoring system.
Brief overview of the remote monitoring system
The remote monitoring system is used for proportioner monitoring in testing mode during maintenance and live firefighting operations.
In the course of remote monitoring, the proportioning rate and other operating parameters are determined, recorded and forwarded to the system operator if necessary. Thus, the smooth functionality and operational readiness of the system are monitored and ensured this way.
A remote monitoring system consists of a control system, including an optional local display unit (HMI) if applicable, and sensor technology. The sensor technology includes, as a minimum, the possibility to determine the water motor’s number of revolutions and to determine the foam agent flow rate. These values are used to calculate the proportioning rate. This figure is the core characteristic during the operation and testing of a foam proportioner. Further sensor technology is available on an optional basis.
The remote monitoring system supports the operating and service personnel on-site. It is also suitable for remote monitoring of the foam proportioner.
However, it is a basic fact that personnel are always necessary to carry out the maintenance work or the proportioning rate testing on-site as the system plays a monitoring role only. It does not actively interact with the functioning of the proportioner.
Evolution – from remote monitoring to remote testing
The question is how to further minimize the maintenance effort on foam proportioners.
The solution lies in the remote testing system, the next step of the intelligent FireDos proportioners. The remote testing system allows monitoring of the proportioner and individual maintenance, including proportioning rate testing.
The condition of the proportioner can be checked without having to start up the fire extinguishing system. No personnel are required on-site. Proportioners in a remote place or that are only rarely inspected by personnel on-site can be checked without maintenance staff and associated expenses, such as travel expenditure. In particular, increasing the testing interval is possible without additional efforts. The instruction manual for FireDos proportioners requires regular starting-up, using the service crank manually as a minimum. This is intended to prevent deposits inside the equipment, impairing its ease of movement and thus conserving the proportioner’s functionality. The remote testing system can adopt these regular movements and test the proportioning rate, increasing the service life and functional safety of the proportioner.
What is the design of a remote testing system?
The remote testing system is generally based upon the remote monitoring system. It is, however, particularly extended by the use of actuators. This is because they enable the completely independent operation of the remote testing system; i.e., the proportioning rate of the proportioner is tested without activating the water pumps of the fire extinguishing system.
The core components include a central control system, with an optional HMI, sensor technology, electrical ball valve drives, an electrical drive for the proportioner and a bypass line past the water motor.
The connection of the electrical drive and the proportioner is designed so that the electrical drive will have no interference with the proportioner’s functionality in the case of a fire. This way, the advantages of the mechanical proportioning principle are preserved.
How does the remote testing system work, and how can the proportioning rate be checked without activating the water pumps?
If in ready-to-operate mode, the proportioner is always in the proportioning position. Upon initiation of an automatic testing process, no matter if after a defined time interval, upon request via a cloud solution or from the fire extinguishing system/a local operator, the proportioner is put into testing operation. Specifically, the control system puts the proportioner into testing operation using an electrically actuated ball valve drive while the foam agent is not mixed into the extinguishing water but returned to the foam agent tank. At the same time, it opens the electrically actuated ball valve in the bypass line past the water motor. Next, the electric drive of the proportioner is activated, driving the complete proportioner at its start-up flow rate. The start-up flow rate is the lowest operating point of a proportioner to reach its nominal proportioning rate.
Due to the external electrical drive, the water motor works like a pump and generates a water flow through the bypass from the water motor’s outlet to the water motor’s inlet. The operation causes no change of pressure in the extinguishing water line. The fire extinguishing system is therefore not influenced when the proportioner is tested.
As the extinguishing water flow rate simulated by the external drive is also known due to the known ratio of the water motor’s number of revolutions and the water flow rate, just the foam agent flow rate must be determined to allow the subsequent calculation of the proportioning rate. This is done by a volumetric flow meter between the proportioning pump’s outlet and the ball valve, which switches between returning and proportioning mode. This allows determination of the foam agent flow rate, both in testing mode and while proportioning in case of an alarm.
The proportioning rate is determined according to the formula as required in the standards and regulations EN 13565-1, NFPA 11, FM 4-12, and the Nordtest NT Fire 042 method.
Foam agent flow rate [l/min]
(Extinguishing water flow rate x 100 = proportioning rate %+ foam agent flow rate) [l/min]
After completion of the testing process, the electric drive of the proportioner stops, the bypass line is closed, and the proportioner is returned to proportioning mode.
Sensor technology installed as an additional option or inside the electric drive allows obtaining further information and conclusions about the state and condition of the respective unit. It is checked, for example, whether the ball valves are in their correct positions or sufficient oil is in the crankshaft housing of the proportioning pump. In addition, the pressure values at the pump inlet/outlet and the pressure at the water motor are recorded. Finally, measuring the entire system’s torque and the flow rate inside the bypass line allows checking the general condition of the proportioner.
The data can be displayed locally or via a cloud solution. Controlling the maintenance operation is also possible via both interfaces.
What if there is an alarm during a testing process?
An important question is: Does the proportioner work without any limitations and as usual if there is an alarm? The answer is: Yes!
The remote testing system is designed in such a way that extinguishing water can flow through the water motor and start it up at any time, even if the electrical drive is working at the same time. In addition, a unique, fully automatic and purely mechanical decoupling mechanism ensures that the electrical drive does not interfere with the proportioner’s functioning and readiness to operate.
In case of an alarm, the ball valves in the bypass line and those for switching between returning and proportioning are immediately switched so that the proportioner is in proportioning mode for firefighting. Thus, the control system is put into alarm mode in this case. This alarm mode causes the disabling of all functions not necessary at that moment and all ball valves to be set to their correct position.
Therefore, in case of an alarm during testing operation, the ball valves switch to their correct position fully automatically and the electric drive is switched off. Even if the electric drive is still running or coming to a stop, the extinguishing water can flow through the water motor and drive the proportioning pump without limitations. The alarm mode of the control system prevents re-activation of the electric drive or any unintended ball valve switching.
What advantages does a remote testing system provide?
Compared with standard proportioners and those equipped with a remote monitoring system, a remote testing system provides various advantages. They feature the following:
- Proportioners can be tested remotely without personnel: No personnel are required on-site for regular proportioning rate testing required per DIN EN 13565-2 and NFPA 11. Hence, no personnel of the system operator or service technician have to be on-site.
- Regular proportioning rate testing: Regular proportioning rate testing ensures optimum functioning of the proportioner in case of a fire. If the proportioning rate is too low, the extinguishing success can be compromised. Overdosing causes the foam agent to be consumed faster than intended, leading to the premature ending of the foam operation.
- Increasing functional and failure safety due to increased testing intervals: An increased test interval causes the proportioner to be tested fully automatically at shorter intervals of time. This notably reduces the risk of a failure remaining undetected for a longer period of time. In addition, more frequent testing prevents the formation of deposits inside the water motor.
- Early fault detection and diagnostics: Faults in the proportioner or parts of the extinguishing system, immediately affecting the proportioner’s functionality, can be identified at an early stage of time. This includes, for example, pressure variations in the extinguishing water line or a jammed suction line.
- Inclusion of all functions and advantages of the remote monitoring system: All functions and advantages of the remote monitoring system are also present in the remote testing system, i.e. all relevant operating parameters are recorded and processed continuously and correctly as well as documented in a log file. In addition, all data are displayed by a visualization.
- Reduction of costs: Regular functional testing makes it possible to detect faults even earlier. This way, maintenance and repairs can take place before any more serious damage occurs. The increased functionality and fault safety of the proportioner ensures that the service life of the proportioners is maximized and the probability of a failure is minimized. As a result, reduced service and operating workforce on-site reduce costs significantly, particularly if the proportioner is located in a remote place. In addition, functional testing of the proportioner allows early identification, analysis and possibly limiting a fault remotely. This makes service visits more efficient and therefore more cost-effective.
Summary and prospect
The remote monitoring system already provides various advantages and helps reduce costs, but it cannot reduce the workforce required on-site.
The remote testing system is a solution for reducing maintenance requirements. It is the next evolution in the course of developing intelligent FireDos proportioners.
The remote testing system allows reducing the workforce required on-site to a minimum, along with shorter testing intervals and increased failure safety. This increases the proportioner’s service life.
If the proportioner is in a fault-free state, no further maintenance by personnel on-site is necessary, apart from an oil change. The oil change can be carried out by the operator’s personnel, too, easily and without any deeper knowledge of the operating principle of proportioners. If a service visit or repair should still become necessary, remote monitoring and early fault detection will make the planning and completion of such work more efficient.
Like the remote monitoring system, the remote testing system is an optimum symbiosis of mechanical proportioners and an intelligent electronic upgrade. Thus, the advantages from both technology fields are combined without compromising the functionality of mechanical FireDos proportioners.
For more information, go to www.firedos.com
About the Author
Jörn Erlenmaier has been working for FireDos since 2018. At first as work-study student and since graduating his Master´s degree in mechatronics he is working as a development engineer. Now he is responsible for the ‘Smart Proportioner’ development at FireDos.
