The invention relates to a fire hydrant with improved sensing and operating properties, comprising a dry column, a head with water outlet and a valve driving element, a base, a valve inserted in the base and opened and closed by the driving element, wherein the valve comprises a piston, a drain tube communicating with the lower part of the interior of the dry column, wherein the base is connected to a water supply grid, a pressure sensor for sensing pressure in the base, an electronic system connected with the pressure sensor and has a wireless transmitter for transmitting at least the sensed pressure values to a remote central control location.

The invention also relates to a method for reporting the operational status of the fire hydrant.

Fire hydrants are important equipment of cities, and they are deployed substantially evenly in living areas so that in case of fire there will be a high-volume water supply available for the firemen in the vicinity of every location. Such hydrants are supplied with water from the municipal water supply grid.

Municipal water supply grids are generally large systems, and it is the task of the operators to maintain the required pressure level everywhere in the system. As pipe breaks or an unusually high local consumptions may always occur, it is an important task how to ensure the required pressure level under such circumstances, or how to notice if (owing to a pipe break) the pressure locally decreases under a critical level. This is why there is a need for the permanent monitoring of the pressure distribution in the whole area of the grid.

This problem has been realized in US 2019/0285604 Al and suggested the placement of the pressure monitoring sensors in existing fire hydrants as they are evenly deployed in the area. In that solution the pressure in the grid is sensed and measured, and there is an option to also measure the water temperature. The sensed values are transmitted from the respective fire hydrants continuously to a central location by wireless transmission. The system has disregarded the fact that the use and control of the hydrant also requires a state- of-the-art electronic status inspection, and when pressure sensors are arranged on the surface of the valve, the leading of connection wires in a rotating central tube is difficult. The uninterrupted transmission of the sensed pressure values has a high energy consumption and at fire hydrants electrical supply cannot be resolved, thus local batteries are needed, and the large consumption requires the frequent replacement of batteries which is a costly task.

Once a central control or operation system is available, there is a need to monitor use and status of the hydrant. Monitoring use means the determination when a use started and terminated, the determination of the volume of water used, and whetherthe use was made by authorized persons. The need for monitoring the status requires information also whether there is a leakage through the hydrant, as valves are arranged under the ground and each hydrant is equipped with a drain tube to allow discharge of water from the dry column after use. Therefore, if a valve leaks, substantial amount of water will get discharged unnoticed.

A further problem lies in that electronic communication with a built-in electronic system requires energy, and this can be provided only by batteries, and the longer a battery can operate, the less maintenance will be required.

In the arrangement of one or more sensors in a fire hydrant several technical difficulties should be overcome, including the safe leading out of wires from the high-pressure side of the valve, through the dry column to the location of the electronic circuits.

The general object of the invention is to solve all the listed problems by providing a fire hydrant with improved sensing and operating properties and a method for reporting the operational status of a fire hydrant.

The primary one of these objectives is how to detect leakages in addition to the safe sensing of the pressure.

A further objective is how to detect when the hydrant is in use and what is the flow rate and water consumption.

A still further objective is to detect and report whether use was initiated by authorized persons or not.

A further last objective lies in how to decrease energy consumption without the decrease of safety and speed of the detection of problems.

These objectives have been solved by the present invention as defined in the attached claims. The invention will now be described in connection with a preferable embodiment thereof, in which reference will be made to the accompanying drawings. In the drawing:

Fig. 1 shows the elevation sectional view of a fire hydrant in which the invention is embedded;

Fig. 2 shows the head portion of the hydrant in enlarged view in half section;

Fig. 3 shows the sectional view of the central part of the hydrant;

Fig. 4 shows the bottom part of the hydrant in section, in still enlarged scale, wherein the valve is closed in the left half, and it is open in the right half;

Fig. 5 is the top view of the bottom part of the hydrant in enlarged scale;

Fig. 6 is a section taken along line VI - VI of Fig. 5;

Fig. 7 is an enlarged detail of the part that includes the pressure and water sensor;

Fig. 8 is a schematic block diagram of the electronic system; and

Fig. 9 A and B are respective time diagrams showing the pressure sensing pulses and the bundle.

The schematic elevation sectional view of fire hydrant 10 in which the present invention has been realized is shown in Fig. 1 in full section, wherein head 11 thereof is illustrated in half section. The fire hydrant 10, as regards its main function is designed as a Hawle 4 break away fire hydrant, commercially available from Hawle Beteiligungsgesellschaft m.b.H. Wag- rainer StraRe 13, A-4840 Vocklabruck, Austria, and its main properties and structural parts are described on the website: htps://www.hawle.com/en/products/hyd rants/h4-break-away-fire-hydrant.

The hydrant 10 has upper and lower columns 12, 13 connected by their respective flanges 14, 15. The lower column 13 is partially dug in the soil and its bottom end is attached to a base 16. The base 16 comprises valve 17 that has a central piston 18 which can be moved in downward direction to open the flow path from the interior of the base 16 to the columns 12, 13. In the closed state of the valve 17 the interior of the columns 12, 13 is dry, any remaining water following a use will be discharged through drain tube 19. The valve 17 can be opened and closed by turning a profiled driving element 20 on the top of the head 11, which is connected to upper end of a driving shaft 21 with treaded lower end and extending centrally in the upper column 12. The threaded lower end of the driving shaft 21 engages a threaded nut 22 which is connected to a vertical driving tube 23 extending centrally in the lower column 13 and its lower end is attached to the piston 18. The driving tube 23 reciprocates in up-down direction as the shaft 21 is turned. Rotation of the threaded nut 22 and the driving tube 22 is prevented.

The base 16 is open from below and it is connected to the high-pressure water supply grid (not shown). The design of the dry barrel of the hydrant 10 using two attached columns

12, 13 serves safety purposes, this enables break away properties, namely if a vehicle or other object during an accident gets pushed to the hydrant, only the upper column 12 will get broken, and the sensitive components under the surface and exposed to high pressure will not be injured.

Figs. 2 to 4 showthe three parts of the hydrant 10 in enlarged scale, wherein Fig. 2 shows the head 11 in half section, and the head 11 has a rectangular body and two opposite surfaces thereof are used as water outlets 24, 25 covered by respective caps 26, U and provided with standard connectors. The rectangular frontal surface of the head 11 shown as lying in the plane of the drawing covers a substantially rectangular frontal cavity 28 which serves as housing for the electronic circuits and system 50 of the hydrant 10. Under the bottom of this cavity 28 a water sensor 29 is arranged for sensing the presence of water in the upper end region of the upper column 12, when the hydrant is in use and water flows through the outlets 24 and/or 25. The water sensor 29 is connected to the electronic circuits in the frontal cavity 28. The frontal cavity 28 is closed by a plastic cover plate 30 onto which or to its vicinity users of the hydrant should place their respective NFC or other identification cards, because to the inside of the cover plate 29 an NFC sensor 59 or the like is placed (see Fig. 8).

Fig. 3 shows the central part of the hydrant with the two interconnected flanges 14, 15 and lower end portion of the upper column 12 and upper end portion of the lower column

13. The indicated assembly at the lower end portion of the rotated driving shaft 21 facilitates the brake away properties of the hydrant which have no role in the present invention.

Fig. 4 shows the base 16 in enlarged scale, wherein the left side shows the piston 18 in closed state and the right side shows it in open state. At the outer cylindrical perimeter of the piston 18 sealing ring 31 is arranged that can be fitted in a cylindrical valve nest 32 when the piston 18 is in closed state, and in such closed state the interior of the hydrant above the sealing ring 31 is dry, any remaining water after use will be discharged through the drain tube 19. In open state when the piston 18 is in its lowest position, there is sufficient space in the spherical lower portion of the base 16 around the piston 18 to provide a wide flow path towards the hollow interior of the lower and upper columns 13, 12. This flow path gets closed when the piston 18 is moved to its uppermost position when the sealing ring 31 is fitted in the valve nest 32.

Following the description of the basic structure of the hydrant 10, reference is made to Figs. 5 to 7 illustrating in respective enlarged views how water pressure is measured under the valve 17 and the presence of water is sensed immediately above the valve 17.

Fig. 5 is the top view of an assembly holding and moving the valve 17 attached to the lower end of the driving tube 23, and Fig. 6 is a sectional view taken along lines VI. -VI. of Fig. 5.

The piston 18 is attached to a holding frame 33 which has three spaced arms extending vertically above the piston and each have a horizontal support rod 34, 35, 36 extending in radial direction and connected to the lower end of the driving tube 23. Of the three arms in Fig. 6 only arm 37 can be seen in section and arm 38 in elevation view. Between the arms there is a large space for allowing water to flow upwards into the interior of the columns towards the outlets 24, 25. The valve piston 18 has a central bore 39 extending till its top surface. A vertical tube 40 is arranged to this top surface and attached to the lower part of the holding fra me 33. In the interior of the vertical tube 40 a sensor assembly 41 is arranged and fixed shown in detail in the enlarged view of Fig. 7.

At the lower portion of the driving tube 23 a circular opening 42 is provided through which cable 43 can be led out into the hollow interior of the lower and upper columns to reach the compartment under the cover plate 30 in the head 11.

The arrangement of the pressure sensor and water sensor in the sensor assembly 41 will now be described in connection with Fig. 7. In the lower end part of the tube 40 a sensor holder 44 is fixed made of a non-conductive plastic material which is sealed from the top of the piston 18 by means of O-ring 45. The sensor holder 44 has a blind hole 46 communicating with the central bore 39 of the piston 18 in which a pressure sensor 47 is fixed, which has a lower sensing face exposed to the pressure of water prevailing in the water grid. The two leads of the pressure sensor 47 are molded in the sensor holder 44 (being covered in Fig. 7) and they extend out in upward direction therefrom. In the upper part of the tube 40 two pins are embedded in a plastic mold 48 that fills this upper part, and the two metal pins 49a, 49b represent lowerwater sensor 49 which detect when water is present in the bottom of the lower column 13, since the upper surface of the plastic mold

48 is arranged close to the bottom of the holding frame 33, which is just under the lower end of the lower column 13 and the two pins 49 a ,b are exposed to water present in the bottom of the holding frame 33. In the presence of water, the electrical resistance between the metal pins 49a, b will decrease and tis can be sensed.

The wires coming from the pressure sensor 47 and water sensor 49 are led in the watertight and protected cable 43, and as described earlier, it extends into the compartment in the head 11 where all electronic circuits are located. Because the driving tube 23 does not turn but only moves up and down when the valve 17 is opened or closed, the cable 43 is not twisted, and the flexibility of the cable allows the vertical displacement during the operation of the valve 17. In Fig. 7 it is illustrated that the cable 43 has a multilayered structure to protect the wires from being wet when being under water. Such waterproof cables are well known in the art and their description is not necessary. Let us also mention that in most embodiments the whole interior of the arrangement shown in Fig. 7 is filled with a self-solidifying plastic material so that the so obtained object is a combined pressure and water sensor.

The operation of the intelligent functions of the fire hydrant 10 will be described with reference to the functional block diagram of the electronic system 50 arranged in the separate compartment of the head 11 under the plastic cover plate 30 and shown in Fig. 8 and in the associated time diagrams of Fig. 9. The system has three sensors P, Wl and Wh which represent the outputs of the pressure sensor 47, the lower arranged water sensor

49 and the higher arranged water sensor 29. The pressure sensor provides continuously the momentary pressure values prevailing in the water grid (mains) just under the hydrant. A/D converter 51 generates digital pressure values in predetermined short intervals, and these values are stored in memory 52 in predetermined subsequent intervals. In an exemplary embodiment the intervals between two subsequent samples last 2 minutes. The A/D converter has three independent units, associated with the respective sensors. Reference is made now to the time diagrams A and B in Fig. 9, wherein diagram A shows the active moments of the pressure date collection, which follow each other in (e.g., 2 minutes long) intervals. A measurement can last through a few milliseconds; therefore the units are sleeping in most of the time. In diagram B it is shown that after a period T (which can be 30 minutes or 1 hour) the data collected in the previous period are all transmitted in a bundle to the central control location 55, where all pressure information will be available during the associated period.

In most of the time the hydrant 10 is not used, and the water sensors Wl and Wh do not deliver the presence of water and their associated A/D converter units have no output signals. For saving battery use, most electronic circuits of the system 50 are set to sleeping mode between the respective 2 minutes long intervals, and the pressure values taken in every 2 minutes are stored in the memory 52. In predetermined sampling intervals T, i.e., in every 30 minutes the previously collected pressure values are read from the memory 52 by a central processor unit (CPU) 53 and these data with their associated time data and the code of the associated hydrant will be sent to a wireless transmitter 54 to forward them to a central control location 55 where data coming from a whole city or district are collected. The availability what pressures prevail in different parts of the district is important information for checking the status of the water grid and can indicate problems in the grid.

This is a valuable service to the district and the city and by integrating the pressure sensors in fire hydrants deployed evenly within the district is much easier and cheaper as if separate pressure meters would have to be installed along the grid within the district.

The properties of the system 50 provide much more information. The pressure data are not only sensed and stored in the memory in 2 minutes intervals, but they are also sent to alert unit 56, which continuously monitors the pressure values, and in case in a predetermined number of sampling moments there is a sudden change in the pressure value that exceeds a predetermined threshold, then the sleeping function will be stopped and the recorded pressure data are immediately sent to the central location 55 associated with an alarm signal so that immediate actions can be carried out if the pressure decrease has been caused by a pipe break.

A further property will be apparent when someone opens the hydrant 10. As soon as water is sensed, first be the lower water sensor Wl and with some delay the upper water sensor Wh will sense water, and these values will be sensed by the alert unit 56, and the processor 53 will then activate an identification unit 57 that is connected with an NFC sensor 58 arranged close to the cover plate 30 to enable sensing when a user places his/her similar NFC unit 59 close to the cover plate 30, whereby an information exchange will take place between the two NFC sensors 58 and units 59, whereby the user identifies himself/herself with an associated code. The identification information is forwarded immediately to the central control location 55 and they will know that the hydrant has been used by an authorized user or in the lack of successful identification by an intruder. The hydrant is not equipped by an activator to prevent water usage when a non-authorized person has started using water, as in emergency situations or of other grounds the operation of the hydrant might be vital, but in any way the authorities will know that the hydrant has been used without authorization. Within a district all persons who are authorized to use the hydrants have respective identification codes and are equipped with an appropriated NFC unit 59. Of course, instead of NFC type connection any other wireless close field communication system can be used.

In addition to the identification of the user when waterflow is sensed, a volume calculator unit 60 is activated, which (under the control of the processor 53) will calculate the volume of water or the flow rate thereof provided by the hydrant. This calculation depends on the momentary pressure and on the special flow resistance properties of the hydrant stored in processor and the duration of the waterflow. In a system which is not equipped with the volume calculator unit 60, the data required for volume calculation are transmitted to the central control location 55 where calculation can be made.

After use of the hydrant, the valve 17 should be closed that stops the flow of water and any water present in the interior of the upper and lower columns 12, 13 will discharge trough the drain tube 19. In case there is a leakage of water through the valve 17, which cannot supply enough water to fill the columns 12, 13 and activate the upper water sensor 29, the lower water sensor 49 will remain active and the signal of only this sensor Wl will be interpreted by the alert unit 56 to transmit leakage information to the central control location 55. In this way they system 50 can not only provide accurate information on the prevailing pressure in the water grid but monitors the usage of the hydrant whether it is authorized or not, also supplies information on the volume of water taken, and independent from any use, signals if there is a leakage in the hydrant that requires maintenance.

The setting of the units in the system into sleeping mode during most of the time decreases electrical consumption, and at the same time information is collected in a continuous way but transmitted in appropriate bundles. By such a solution a new battery can last through several years, whereby maintenance costs will be reduced substantially.