The disclosure relates to fire suppression. More particularly, the disclosure relates to monitoring of fire suppressant storage tanks.
Liquid fire suppression agents have been used for decades. Although some agents such as hydrofluorocarbon (HFC) (e.g. Halon 1301 (bromotrifluoromethane) and HFC-227ea (heptafluoropropane)) are in disfavor due to environmental concerns, replacements are readily commercially available, such as a fluoroketone formulated as dodecafluoro-2-methylpentan-3-one (1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-pentanone) (CF3CF2C(O)CF(CF3)2) (ASHRAE nomenclature FK-5-1-12). Such agents are typically used with a pressurant/propellant such as N2. Kidde-Fenwal, Inc. of Ashland, Mass. manufactures an exemplary fire suppression system, the Kidde® ADS™. Other suppressant agents and pressurants/propellants may be used in fire suppression systems as necessary to meet desired fire suppression capabilities.
Typically such agents are stored as a liquid in one or more metal tanks (e.g., steel tanks having a cylindrical centerbody and domed ends, although other shapes and materials are also known in the art). A tank is typically positioned with its axis vertical so that one end is an upper end or top and the other a lower end or base. The upper end typically has a number of ports with fittings (e.g., threaded fittings). Typically a large center port receives a discharge assembly. The discharge assembly may include a fitting portion mated to the tank fitting and an external valve (e.g., automatically controllable via a control system). A discharge conduit (also known as a siphon tube or dip tube) extends downward into the tank and typically has an open lower end near the bottom of the tank. In facility configurations requiring multiple tanks, the tanks may be connected to a suppression system serially, independently, or in distributed locations in different configurations, and may be co-located or distributed throughout a facility. The suppression system includes piping from the tank(s) to endpoints such as discharge nozzles. Various pressure regulators and controllable valves may be located along the piping to provide selective discharge of suppressants at locations of fire.
Due to their low heat of evaporation and high vapor pressure (e.g., relative to water), typical liquid fire suppression agents will rapidly vaporize at discharge from the nozzle outlets and thus be delivered as vapor.
If the discharge valve is opened, pressure in the tank headspace (e.g., from the pressurant/propellant noted above) is sufficient to drive liquid suppressant up through the discharge conduit and out of the tank. Pre-use, the surface level of liquid in the tank will typically be well into the upper half of the tank. The exact position will depend on factors including the nature of the suppressant, the nature of the pressurant/propellant (e.g. composition and whether internally or externally located), and the application.
It is necessary to at least occasionally measure the fluid level in the tank (e.g., safety regulations typically require semi-annual inspection including verification of agent amount). To do this without venting the tank, several liquid level measurement systems have been proposed. A number of these systems make use of an additional vertically-extending conduit mounted to an additional port in the tank upper end. Typically, the tanks may be provided with multiple smaller off-center ports (e.g., with internally-threaded fittings) in addition to the center port. These ports may serve for various functions. An exemplary such liquid level sensing system has a fitting mounted to one of those additional port fittings with a conduit (e.g., metal tube) extending vertically down toward the base of the tank. Unlike the discharge conduit, the lower end of this liquid level sensing tube is closed so that the interior of the liquid level sensing tube is sealed relative to the surrounding interior of the tank. A float may surround the liquid level sensing tube. The float may be magnetized. The float may magnetically interact with a member movable within the tube to in turn provide indication of the liquid level.
In one basic example of such a liquid level sensing system, the liquid level sensing fitting, in turn, has a removable cap or plug providing access to the upper end of the tube. A magnetic weight at the end of a measuring tape, string, or other device, may be located in the tube. The magnetic weight will interact with the float to be held at the same level as the float and thus at the level of the surface of liquid in the tank. This allows the level of the surface of liquid in the tank to be measured relative to the liquid level sensing fitting and thus relative to any other reference on the tank. Such measurements are typically taken periodically manually by a person assigned to the task. In one example where the weight and measuring tape are already in the tube, the end of the tape opposite the weight may be connected to the removable cap or plug. The user may open the cap or plug and pull to take up slack in the measuring tape. The user may take a reading with the tape to determine the liquid level of the tank.
Yet more complex systems are automated with the magnetic weight permanently within the tube and its vertical position electronically measured. Yet other systems involve capacitive measurements between inner and outer tubes.
Monitoring of the fire suppression system is typically performed by a fire control panel adjacent the tank(s). The fire control panel may be coupled to one or more sensors or switches on each tank. For example, sensors may include pressure sensors and liquid level sensors and switches may include the control head placement sensor. Exemplary pressure sensors may effectively be switches in that they are set to open or close a circuit at a threshold pressure. The threshold may be set when the fire suppression system is manufactured.
The control head is part of the discharge assembly and actuates a discharge valve on the tank. An exemplary control head placement sensor is disclosed in International Application Pub. No. WO/2016/196104, Publication Date Aug. 8, 2016, of UTC FIRE & SECURITY CORPORATION and inventor Thomas Kjellman, and entitled “EXTERNALLY MOUNTED DEVICE FOR THE SUPERVISION OF A FIRE SUPPRESSION SYSTEM”, the disclosure of which is incorporated by reference in its entirety herein as if set forth at length. The control head placement sensor is mounted to the tank and has a switch which is depressed by the presence of a control head of the discharge assembly. The switch may be a normally closed switch or a normally open switch.
Additionally, some stock switches are dual output switches that have three connections/conductors/poles: a common connection (“common”); a normally closed (NC) connection; and a normally open (NO) connection. When such a switch is undepressed, there is no continuity between the normally open pole and the common but there is continuity between the normally closed pole and the common. When the switch is depressed, however, there is conductivity between the normally open pole and common while lacking continuity between the normally closed pole and the common. Some of the normally closed poles and normally open poles may be connected to the fire control panel; whereas, the other may be disconnected from any external device.
The fire control panel monitors and controls the fire suppression system. It collects sensor input from detectors such as smoke sensors and user input devices such as pull boxes. It analyzes sensor inputs to determine if a fault, warning, or alarm condition is present. It communicates this system status locally (e.g., display or status light) and may communicate this status remotely (e.g., via a telephone line or Ethernet or cellular to a remote monitoring station (e.g., computer at a third party monitoring company or fire department)). Depending on the determined status condition (e.g., fault, warning, alarm), the fire control panel controls appropriate connected devices. For example, during alarm condition, the fire control panel may activate notification devices such as strobes and horns and initiate suppressant discharge by activating control heads connected to the suppressant tanks.
The construction and operational parameters of the fire control panels are subject to numerous constraints. For example, there may be code requirements and industry standard requirements (e.g., requirements for a listing by Underwriters Laboratory (UL) or other certification body). In addition to restricting construction and operation of fire control panels, generally, such codes, standards, and approval requirements also affect any updates or retrofits/modifications. For example, if a manufacturer wants to sell an updated version of an approved fire control panel with new constructional details or operational features, the updated version may be subject to requirements for re-approval/re-certification. Similarly, an in-field modification of an existing fire control panel may require such re-approval/re-certification. The in-field modification may also require expensive inspection.
One aspect of the disclosure involves a fire suppression system comprising: a plurality of tank units each comprising: a tank body having a first port and an interior for storing at least one of fire suppressant and driver gas; a discharge assembly mounted to the first port and comprising: a discharge valve; and a first monitoring switch or sensor. A first monitoring unit is coupled to the first monitoring switch or sensor of each said tank unit and configured to communicate with a remote monitoring location. The system further comprises, for each of the tank units: a second monitoring switch or sensor; and a second monitoring unit coupled to said second monitoring switch or sensor and configured to communicate with the remote monitoring location.
In one or more embodiments of any of the other embodiments, the fire suppression unit further comprises a hazard sensor and the first monitoring unit comprises an input from the hazard sensor.
In one or more embodiments of any of the other embodiments, the hazard sensor comprises a smoke detector.
In one or more embodiments of any of the other embodiments, the fire suppression system further comprises a pull box and the first monitoring unit comprises an input from the pull box.
In one or more embodiments of any of the other embodiments, the discharge assembly comprises a control head and the first monitoring unit comprises a control output to the control head.
In one or more embodiments of any of the other embodiments, for each of the tank units, the second monitoring switch or sensor comprises a liquid level sensor not connected to the first monitoring unit.
In one or more embodiments of any of the other embodiments, the second monitoring unit comprises a radio.
In one or more embodiments of any of the other embodiments, the first monitoring switch or sensor is selected from the group consisting of pressure switches or sensors and control head placement switches or sensors.
In one or more embodiments of any of the other embodiments, the second monitoring switch or sensor is not coupled to the first monitoring system.
In one or more embodiments of any of the other embodiments, a hand held device is in wireless communication with each second monitoring unit.
In one or more embodiments of any of the other embodiments, a gateway is in wireless communication with each second monitoring unit, each second monitoring unit configured to communicate with the remote monitoring location via the gateway.
In one or more embodiments of any of the other embodiments, the gateway comprises memory storing information from the second monitoring units.
In one or more embodiments of any of the other embodiments, the second monitoring units are configured to communicate with each other.
In one or more embodiments of any of the other embodiments, the second monitoring units are configured to communicate directly with each other.
In one or more embodiments of any of the other embodiments, the second monitoring units are configured to communicate (421) with each other via Bluetooth mesh networking.
In one or more embodiments of any of the other embodiments, the second monitoring units are configured to each store status data from all the second monitoring units so that any of the second monitoring units may communicate said data to a local handheld device.
In one or more embodiments of any of the other embodiments, the second monitoring units are configured to each store said status data from all the second monitoring units at predetermined times; and the second monitoring units are configured so a user of the local handheld device may manually activate said any of the second monitoring units to communicate said data to the local handheld device.
In one or more embodiments of any of the other embodiments, the second monitoring units are configured to wake up from a sleep mode in response to input from the second monitoring switch or sensor or the first monitoring switch or sensor.
In one or more embodiments of any of the other embodiments, a method for using the system comprises: with the first monitoring unit, receiving input from one or more hazard sensors or pull boxes; and with each second monitoring unit, communicating status via a radio.
In one or more embodiments of any of the other embodiments, the method further comprises, with the first monitoring unit, controlling suppressant delivery.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.
Like reference numbers and designations in the various drawings indicate like elements.
The exemplary source 22 includes multiple tanks 34 of suppressant (agent). The exemplary configuration is a remote driver configuration where the pressurant for each agent tank is remote of that tank. An exemplary agent is a liquid agent and an exemplary pressurant is nitrogen and/or argon.
To handle situations where a single suppressant tank is insufficient to protect hazard locations 26, the suppressant source 22 contains additional, secondary units 44, 46. These secondary units are each equipped with a pneumatic control head 202 (
The system 20 may further include a reserve unit 42 which may be controlled independently of the primary and secondary units. This may be used to address re-ignition situations or situations where the primary and secondary units are insufficient to even temporarily extinguish a hazardous condition. The reserve unit may itself be a primary unit having one or more associated secondary units.
As shown in
The flowpaths 24 (
The flowpaths 24 comprise respective legs 80 though conduits 82 (
However in alternative (integrated) situations either the agent itself is also a pressurant (e.g., inert gas systems) or the pressurant is stored in the headspace of the agent tank and the driver tanks are not required. In that case, the electronic control head(s) 200 and pneumatic control heads 202 are located on the corresponding suppressant tanks.
The exemplary suppression system 20 has pressure switch sensors 240 (
The fire control panel 100 is schematically represented in
As so far described, the system is merely one example of a baseline system to which further modifications may be made. An exemplary modified system discussed below adds a parallel monitoring functionality to that already provided by the baseline. The exemplary modified system makes use of dual output sensors or switches (collectively “switches” unless indicated to the contrary) if present or provides dual output switches for parallel monitoring of a given switch. The modified system may add monitoring functions (and associated switches) not present in the baseline. In one example, the added functionality is a liquid level monitoring functionality using a liquid level sensor 260 (
As is discussed further below, each monitor module 340 may include visual output devices such as a display 362 (
The microcontroller 377 stores in the memory 378 status information for the sensors attached to the associated suppression unit 40, 42, 44, or 46. Such information may include any combination of parameters such as: suppression unit identifying information (e.g., identification or serial number); the control head placement switch sensor 230 status (e.g., attached or disconnected); the pressure switch sensor 240 status (e.g., OK or low pressure); the agent temperature (e.g. from a temperature sensor (e.g., 261), such as a thermistor on or in the suppressant tank); the agent level within the tank (e.g., from the liquid level sensor 260); the computed agent mass (e.g., from the measured temperature and the agent level data); the monitor module battery 379 charge level; the monitor module connectivity status (e.g., connected to other monitor module(s), connected to hand held device 400 (
In the particular example, while the sensors 230, 240 are connected to fire control panel 100 through their normally closed (NC) terminals, the normally open (NO) terminals are connected to the monitor module 340. The reversed configuration is also possible with NC sensor switch terminals connected to the control panel and the NO terminals connected to the monitor module. The monitor module 340 offers localization of the fault condition warning at each individual unit. This offers significantly simplified system inspection for fault conditions.
In addition, the exemplary monitor module 340 is connected to electronic level sensor 260 via connection 354 (
Communication between the monitor modules 340 and the hand held device may be direct for all monitor modules 340 or may be direct for some but indirect for others. As an example, the monitor modules 340 may be spread far enough apart that the hand held device can't communicate with all of them from a given location (e.g., the total span exceeds Bluetooth range). However, the gaps between monitor modules 340 may be small enough to allow chained communication 421 (e.g., with gaps less than Bluetooth range). Thus, each of the monitor modules 340 may be configured to share its data via chained inter-module communication 421 with all the other modules and store such data from all the modules. Thus, when a technician arrives, the technician's hand held device 400 may communicate 421 with just one module 340 to acquire data from all.
Such chained communication or other inter-module communication 421 has uses even where all modules 340 are within range of each other or the hand held device. For example, to save power, the modules 340 may be configured to normally be in a low power sleep mode and wake up to store and share data at specific times (e.g., daily at 12 am and 12 pm). The technician arriving between such times may then manually awaken one of the modules 340 (e.g., by pressing a button/switch) to then establish communication 420 between that module and the hand held device to then download to the hand held device the data from all modules 340 stored on the single awake module.
As discussed above, one characteristic of some embodiments of the monitoring module is to share a sensor or switch with the fire control panel 100 by using different poles or other outputs of that sensor or switch.
With only one of the normally open (NO) conductor and normally closed (NC) conductor of a given such switch coupled to the fire control panel, the other is free for use in a secondary monitoring system such as the monitor module 340. Coupling of the secondary monitoring system to the otherwise unused contact does not affect code or other compliance. Thus, the addition of or subsequent modifications to the secondary monitoring system may be made without all the complications required to make modifications to the fire control panel.
As a further variation in cases with liquid suppressant, further aspects of suppressant condition may be monitored. For example, in
Water flow rates may be monitored during the discharge via a mass flow meter 290 (
The liquid quality sensor and mass flow rate information are sent as inputs 356, 358 alongside 350, 352, 354.
The use of “first”, “second”, and the like in the description and following claims is for differentiation within the claim only and does not necessarily indicate relative or absolute importance or temporal order. Similarly, the identification in a claim of one element as “first” (or the like) does not preclude such “first” element from identifying an element that is referred to as “second” (or the like) in another claim or in the description.
One or more embodiments have been described. Nevertheless, it will be understood that various modifications may be made. For example, when applied to an existing basic system, details of such configuration or its associated use may influence details of particular implementations. Accordingly, other embodiments are within the scope of the following claims.
Benefit is claimed of U.S. Patent Application No. 62/773,450, filed Nov. 30, 2018, and entitled “Fire Suppression System Remote Monitoring”, the disclosure of which is incorporated by reference herein in its entirety as if set forth at length.
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