Abstract:
The present invention provides a pressure alarm for use in conjunction with conventional pressure gauge unit systems, as a replacement pressure gauge and alarm, or as a pressure alarm system. The invention provides adaptable alarm feedback signals for an operator, preventing the unexpected loss of pressure when using a gas cylinder, pressure boiler, or other device. The invention provides an alarm that may be a visual, audible, electronic, or mechanical low-pressure alarm and may include a means of ordering replacement supplies or sending a warning message. A system controller and memory module prevents false alarms and eases the burden of the operator while allowing external input and control.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a pressure alarm device. More specifically, the present invention relates to a pressure alarm device operable with, or incorporated into, a pressure gauge incorporated into a pressure regulator for a gas cylinder. 
     2. Description of the Related Art 
     Balloons and inflatable advertising displays are often filled with conventional gas cylinder units. Most frequently, this type of conventional gas cylinder unit includes a gas cylinder containing Helium (He), but other conventional non-combustible gasses (Nitrogen and Argon) are also used. 
     In some circumstances, conventional gas cylinder units also include a control mechanism, frequently placed on the top of the gas cylinder for user convenience. Conventional gas cylinder control mechanisms are threaded into the top of the gas cylinder and are often actuated by a control valve of conventional design. Conventional control mechanisms include a pressure control valve (usually a ball or a needle valve), a combination pressure regulator and gauge, and at least one male filling adapter that mates with a balloon or display opening during filling to provide a gas tight seal. Frequently, multiple male extensions are used to allow ready adaptation with a variety of balloon types. 
     Conventionally combined pressure regulator and gauge sets include a conventional regulator with a visual gauge and a safety pressure relief device or over-pressure vent opening. Conventional visual gauges have a body enclosing a face and an indicator needle. The needle is registered against a scale printed on the face of the gauge. The needle is most frequently connected to a conventional Bourdon-tube type gauge movement and directly reflects an existing gas cylinder pressure when the conventional regulator is open. Using this type of combined regulator/gauge set, operators may both regulate the available pressure (by opening and closing the regulator) and monitor the existing gas cylinder pressure by viewing the visual gauge. 
     In an alternative conventional circumstance, a pressure regulator gauge is connected to a propane (LP) cylinder of the type normally associated with a back-yard gas grill. A control valve, in a direct line with the gauge, opens the LP cylinder providing propane access to the grill via a braided hose and a set of quick-disconnect fittings. In use, an operator connects the braided hose to a coupling down stream from the pressure regulator gauge. As the operator opens the valve, the gauge reads the tank pressure. As the LP gas is used, the gauge generally reflects the remaining pressure in the tank and hence the remaining volume of LP gas. 
     In either conventional circumstance, certain design and safety standards may govern the type of connections and fittings which are used. Particularly of note are the design and safety standards governing conventional pressure regulator gauges are prepared by the Compressed Gas Association (CGA) and other governmental bodies to protect the public. 
     Unfortunately, end users for either type of conventional gas cylinder unit (LP, He, N, etc.) are often untrained and unsophisticated in monitoring the visual gauges and scheduling appropriate replacement gas cylinder delivery. Additionally, the balloon/entertainment and advertisement industries often cannot afford to competently train end users and may experience sudden workflow changes making reliable and regular cylinder replacement scheduling difficult. Over ordering of replacement gas cylinders increases inventory costs. Under ordering of replacement gas cylinder results in sudden operational shut down and client loss. Finally, conventional indicator needle-type combination pressure regulator gauges often include small and inaccurate scales and are often difficult to read from any distance. 
     Attempts to make conventional visual gauges more useful include labeling the gauge face, adjacent a zero (0) pressure value, a warning color or other indicia of low pressure. One conventional gauge-less regulator (without a needle-type gauge) includes a spring-loaded “pop-up” indicator providing a visual indicator of low pressure. Unfortunately, these conventional low-pressure warning systems are small, are hard to read, are easily hidden by dirt, or require experience or training to read. Unfortunately, there is no conventionally available and adaptable alarm system for conventional types of gas cylinder units that would overcome these problems and provide easy end user with a simple and cheap warning prior to emptying the gas cylinder. 
     While complex conventional pressure sensing and alarm system exist, these systems require custom design and are often regulated by external and large computerized feed-back and pressure-check loops, the high cost and maintenance fees associated with acquisition and operation of these systems is prohibitive to the home grilling, balloon, and advertising display industry. Additionally, these large conventional pressure sensing and alarm systems often require lengthy hard-wire connections with separate computer modules and a full time power supply to function reliably. 
     In summary, the problems of commercially available combination pressure regulator gauges include:
         1. Lack of positive audible, visible, or vibratory alarm signal to warn unskilled end users of low-pressure level.   2. High purchase, installation, and maintenance costs for conventionally available systems.   3. Poor gauge face resolution making accurate gauge reading difficult by unsophisticated end users.   4. Lack of adaptable pressure alarms that can be applied to existing conventional pressure regulator gauges in the field without complex or hard-wire support systems for power supplies and sensor operation.   5. Low portability and difficulty in repositioning on replacement modules.   6. Lack of easy communication and/or control between a gauge and an off-site monitor, controller, owner.       

     SELECTED OBJECTS AND SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an invention that overcomes the detriments of conventional alarm devices discussed above. 
     Another object of the present invention is to provide a pressure alarm device and an adaptable alarm system that allows easy adaptation to conventional pressure gauges or easy replacement of conventional pressure gauges. 
     It is another object of the present invention to provide a pressure alarm that is readily adaptable to a variety of difficult operational environments and conditions. 
     It is another object of the present invention to provide a pressure alarm device with multiple types of low pressure alarms. 
     Another object of the present invention is to provide a pressure alarm system that is easily used by unsophisticated end users and is inexpensive or generally costless to operate. Another object of the present invention is to provide a pressure alarm device, wherein a pressure gauge and an alarm device are combined and conveniently adaptable to conventional pressure systems. 
     Another object of the present invention is to provide a pressure alarm and pressure control system, wherein a pressure control system includes an alarm device. 
     Another object of the present invention is to provide a pressure alarm and pressure control system linked to and operable with a communication interface for sending pressure alarm, control, and other operational data and for receiving controlling informational pressure alarm data from an external control source. 
     Another object of the present invention is to provide a pressure alarm and pressure alarm control system linkable with a communication interface for sending pressure alarm data and for receiving controlling or inquiry pressure alarm data from an external source via wireless signals, between at least one of the pressure alarm body and communication interface and an external control source. 
     Another object of the present invention is to provide a pressure alarm device, having a system controller adapted to monitor a tank pressure and upon reaching a programmable and up-datable pressure low-point, provides and generates at least one of a low pressure alarm and a re-supply order or email alarm message via the world-wide net. 
     The present invention relates to a pressure alarm device for use either in conjunction with conventional pressure gauge unit systems or as a replacement pressure gauge. The invention provides multiple types of adaptable and programmable alarm feedback for an operator that prevents unexpected loss of pressure when using a gas cylinder. The invention provides at least one of a visual, audible, or mechanical low-pressure alarm either directly or via the world wide web, cellular telecommunication systems, or paging communication systems. A system controller and memory module prevents false alarms and ease operator burdens while providing programmable operator instructions. 
     According to one embodiment of the present invention, there is provided, a pressure alarm device, for a pressure gauge having an indicator needle operable about a pivot, the pressure alarm device comprising: an alarm body, at least a first means for sensing at least a first desired position of the needle relative to the pivot during a use of the pressure gauge and for creating a corresponding position signal, the means for sensing and creating operably joined to the alarm body, means for retaining the alarm body proximate the pressure gauge and for positioning the means for sensing relative to the first desired position, alarm circuit means for receiving the position signal and for generating at least one alarm signal, the means for receiving and generating operably joined to the alarm body, and means for supplying power to the alarm circuit means, whereby during the use when the means for sensing and creating determines the needle is at the at least first desired position and creates the corresponding position signal, the alarm circuit means receives the position signal and generates the at least one alarm signal. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, further comprising: at least one alarm generating component in the alarm circuit means, the at least one alarm component generating the at least one alarm signal, the at least one alarm component being at least one of an audible alarm unit, a visual alarm unit, an wired electronic message alarm unit, a wireless electronic message alarm unit, and a mechanical alarm unit, and the at least one alarm signal being at least one of an audible signal, a visual signal, an electronic signal, an electronic message signal, and a mechanical signal, whereby the one at least one alarm component is effective to notify a user of the alarm signal. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the means for retaining and positioning the alarm body proximate the pressure gauge includes at least one of an elastomeric member system, a cover system, and an adhesive system. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the elastomeric member system includes an elongated elastic member, the elastic member elastically retaining and repositionably holding the alarm body relative to an outer circumference of the pressure gauge, the elastic member enabling the user to position and retain the alarm body along the outer circumference relative to the first desired position, and the elastic member urging the alarm body into a stabilizing close contact with the outer circumference during the use, whereby the means for sensing reliably senses the needle relative to the first desired position during the use. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, further comprising: a pair of support arms extending outward from the alarm body, the support arms including at least concave contact surfaces, and the elastic member urging the concave contact surfaces into a mating contact with a selected convex portion of the outer circumference during the use, whereby the support arms align the alarm body with the pressure gauge during the use and guide the alarm body about the outer circumference during a repositioning. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the cover system includes at least a cover front and a cover back, the means for sensing and for creating the position signal in the cover front, the cover front covering at least a portion of a face of the pressure gauge, the cover back covering at least a portion of a back of the pressure gauge, and means for connecting and positioning the cover front relative to the cover back and enabling an alignment of the means for sensing and creating relative to the at least first desired position, whereby the cover system enables ready adaptation of the pressure alarm device to preexisting the pressure gauge. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, further comprising: a sliding snap lock connection in the means for connecting and positioning, the sliding snap lock connection including a sliding-snap male member and a sliding-snap female member on respective the cover front and the cover back, and the sliding-snap male member and the sliding-snap female member enabling positive engagement between the cover front and the cover back while permitting rotation of the cover front relative to the pressure gauge, whereby the user may reposition the means for sensing relative to the needle during the use. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the pressure alarm device includes the adhesive system fixably joining the alarm body to the pressure gauge after a positioning of the means for sensing relative to the at least first position, whereby the alarm body is reliably and cheaply secured to the alarm body. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, further comprising: a sensor arm member in the alarm body, the means for sensing in the sensor arm member, the sensor arm member being extendable from the alarm body along a front face of the pressure gauge, and the sensor arm member positioning the means for sensing at the first desired position, whereby the sensor arm and the means for sensing do not detrimentally interfere with the users view of the front face and the needle during the use. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the sensor arm member includes one of a transparent and a translucent material. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the sensor arm rigidly extends from the alarm body along the front face. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, further comprising: a pivot hinge, the pivot hinge pivotally joining the sensor arm to the alarm body, the pivot hinge enabling an extension of the sensor arm along the front face of the pressure gauge during the use, and the pivot hinge enabling a retraction of the sensor arm away from the pressure gauge prior to the use, whereby the user can easily view the pressure gauge during the use and position sensor arm and the means for sensing at the first desired position. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the alarm body includes a first indicator mark along a radian extending from the pivot, whereby the first indicator mark enables simple user alignment of the alarm body with a desired position on a pressure scale of the pressure gauge, and the means for sensing on the sensor arm positioned at a selected offset angle distant from the first indicator mark, whereby when the user aligns the first indicator mark with the desired position on the pressure scale, and pivots the sensor arm to extend along the front face, the sensor means is positioned at the first desired position the selected offset angle. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, further comprising: at least one system controller in the alarm circuit means, the at least one system controller monitoring the alarm circuit during the use and determining a validity of the position signal based upon a predetermined acceptable position signal profile, and the system controller actuating the at least one alarm generating component, whereby the system controller prevents false alarm signals and conserves alarm circuit energy. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, further comprising: at least one memory device in the alarm circuit means, the memory device retaining at least one validity parameter and the predetermined acceptable position signal profile, and the system controller comparing the position signal to the at least one validity parameter and the predetermined position signal profile during the use, whereby the system controller determines a validity of the position signal relative to both the at least one validity parameter and the acceptable position signal profile. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the visual alarm unit is at least one of an LED unit, a LCD unit, and an incandescent unit effective for generating the visual signal, the LED unit and the incandescent unit generating the visual signal as at least one of a constant and a flashing visual signal, the LCD unit generating the visual signal is at least one of a message alarm, an instructional alarm, and a warning alarm on an LCD screen, and the visual signal is at least one of a blinking message alarm on and a constant message alarm displayed the LCD screen. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the audible alarm unit is at least one of a speaker unit and a horn unit effective for generating the audible signal, the speaker unit including means for storing a recorded alarm message and issuing the recorded alarm message as the audible signal, and the horn unit including means for generating a tonal sound as the audible signal. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the mechanical alarm unit is at least one of an eccentric vibratory unit and a flag unit effective for generating the mechanical signal, the eccentric vibratory unit including means for providing vibration to the pressure alarm devise based upon a rotating weight eccentric to a rotational axis and for generating the mechanical signal as a vibration, and the flag unit including means for providing a visible mechanical flag on the pressure alarm device and for generating the mechanical signal as a motion of the visible mechanical flat. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the electronic signal unit is at least one of a wired and a wireless electronic signal unit, and the electronic signal unit effective for generating an electronic alarm signal and sending the alarm signal to a communications interface during the use, whereby the electronic signal includes information indicating at least one of an alarm condition of the pressure alarm device and an electronic resupply order for the pressure alarm device. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the electronic message signal unit is at least one of a wired and a wireless electronic signal unit, and the electronic message signal unit is effective for generating an electronic message alarm signal to a communications interface during the use, whereby the electronic signal includes information indicating at least one of an alarm condition of the pressure alarm device and an electronic resupply order for the pressure alarm device. 
     According to another embodiment of the present invention, there is provided, a pressure alarm device, comprising: a pressure alarm, a pressure gauge, the pressure gauge including an indicator needle operable about a pivot relative to a pressure scale upon an introduction of an external gas pressure, the pressure alarm including at least a first means for sensing at least a first desired position of the needle during a use of the pressure alarm device and for creating a corresponding position signal, alarm circuit means in the pressure alarm for receiving the position signal and for generating at least a one alarm signal, and means for supplying power to the alarm circuit means, whereby during the use when the external gas pressure is applied and the means for sensing and creating determines when the needle is at the first desired position and creates the corresponding position signal, the alarm circuit means generates the at least one alarm signal. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, further comprising: at least one alarm generating component in the alarm circuit means, the at least one alarm component generating the at least one alarm signal, the at least one alarm component being one of an audible alarm unit, a visual alarm unit, an electronic signal alarm unit, an electronic message alarm unit, and a mechanical alarm unit, and the at least one alarm signal being at least one of an audible signal, a visual signal, an electronic signal, an electronic message signal, and a mechanical signal. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: at least one system controller in the alarm circuit means, the at least one system controller monitoring at least the alarm circuit means during the use and determining at least a validity of the position signal based upon a predetermined acceptable position signal profile, and the system controller actuating the at least one alarm generating component, whereby the system controller prevents false alarm signals and conserves an alarm circuit energy. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, further comprising: at least one memory device in the alarm circuit means, the memory device retaining at least one validity parameter and the predetermined acceptable position signal profile, and the system controller comparing the position signal to the at least one validity parameter and the predetermined position signal profile during the use, whereby the system controller determines a validity of the position signal relative to both the at least one validity parameter and the acceptable position signal profile. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the visual alarm unit is at least one of an LED unit, a LCD unit, and an incandescent unit effective for generating the visual signal, the LED unit and the incandescent unit generating the visual signal as at least one of a constant and a flashing visual signal, and the LCD unit generating the visual signal as at least one of a constant message alarm on an LCD screen and a blinking message alarm on the LCD screen. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the audible alarm unit is at least one of a speaker unit and a horn unit effective for generating the audible signal, the speaker unit including means for storing a recorded alarm message and issuing the recorded alarm message as the audible signal, and the horn unit including means for generating a tonal sound as the audible signal. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the mechanical alarm unit is at least one of an eccentric vibratory unit and a flag unit effective for generating the mechanical signal, the eccentric vibratory unit including means for providing vibration to the pressure alarm devise based upon a rotating weight eccentric to a rotational axis and for generating the mechanical signal as a vibration, and The flag unit including means for providing a visible mechanical flag on the pressure alarm device and for generating the mechanical signal as a motion of the visible mechanical flat. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the electronic signal unit is at least one of a wired and a wireless electronic signal unit, and the electronic signal unit effective for generating an electronic alarm signal and sending the alarm signal to a communications interface during the use, whereby the electronic signal includes information indicating at least one of an alarm condition of the pressure alarm device and an electronic resupply order for the pressure alarm device. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the electronic message signal unit is at least one of a wired and a wireless electronic signal unit, and the electronic message signal unit is effective for generating an electronic message alarm signal to a communications interface during the use, whereby the electronic signal includes information indicating at least one of an alarm condition of the pressure alarm device and an electronic resupply order for the pressure alarm device. 
     According to another embodiment of the present invention there is provided a pressure alarm system, adaptable to a pressure supply system, comprising: a pressure stem, the pressure stem in a pressure communication with the pressure supply system, the pressure supply system including at least one gas cylinder, at least a pressure diaphragm in a pressure communication with the pressure stem, at least one male pressure release device in an operable pressure communication with the pressure stem, whereby the at least one pressure release device enables filling external items with a pressurized gas released from the gas cylinder during a use, a pressure alarm device in a pressure communication with the pressure stem, comprising: at least a first pressure gauge and at least a first pressure alarm, the pressure gauge having an indicator needle operable about a pivot during the use, at least a first means for sensing at least a first desired position of the needle during the use and for creating at least a first corresponding position signal, alarm circuit means for receiving the position signal and for generating at least one alarm signal, both the means for sensing and creating and the alarm circuit means in the pressure alarm, and means for supplying power to the alarm circuit means, whereby during the use, when the means for sensing determines the needle is at the at least first desired position, the means for sensing creates the corresponding position signal and the alarm circuit means generates the at least one alarm signal. 
     According to another embodiment of the present invention there is provided a method of applying a pressure alarm device to an existing pressure gauge having a pressure indicator needle operable about a pivot, the method comprising the steps of: positioning the pressure alarm device on the pressure gauge, adjustably securing the pressure alarm to the pressure gauge, determining a users desired amount of warning prior to reaching an empty state on the pressure gauge, aligning means for sensing and creating in the pressure alarm device to sense at least a first desired position of the needle during a use of the gauge and create a corresponding position signal, the first desired position being the users desired amount of warning prior to reaching the empty state, and enabling an alarm circuit means in the pressure alarm device to receive the position signal and generate at least one alarm signal. 
     According to another embodiment of the present invention, there is further provided a method of replacing a pressure gauge, wherein the step of adjustably securing includes a step of engaging at least one of an elastomeric member system, a cover system, and an adhesive system as a means for adjustably positioning and securing the pressure alarm to the pressure gauge. 
     According to another embodiment of the present invention, there is provided a method of replacing an existing pressure gauge with a pressure alarm device, comprising the steps of: disconnecting the existing pressure gauge from a first pressure engagement, connecting the pressure alarm device to the first pressure engagement, the pressure alarm device comprising: a pressure alarm, a pressure gauge, the pressure gauge including an indicator needle operable about a pivot relative to a pressure scale upon an introduction of an external gas pressure, the pressure alarm including at least a first means for sensing at least a first desired position of the needle during a use of the pressure alarm device and for creating a corresponding position signal, alarm circuit means in the pressure alarm for receiving the position signal and for generating at least one alarm signal, and means for supplying power to the alarm circuit means, whereby during the use, when the external gas pressure is applied and the means for sensing and creating determines the needle is at the first desired position and creates the corresponding position signal, the alarm circuit means generates the at least one alarm signal. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, according to claim  15 , further comprising: at least means for receiving external electronic control signals in the at least one system controller, and the electronic control signals allowing an external operator to submit control instructions to the controller during the use and to store the control instructions in the at least one memory device, whereby the system controller enables an electronic control of the pressure alarm device from a remote communications position. 
     According to another embodiment of the present invention, there is provided a pressure alarm device, wherein: the means for receiving includes means for receiving the control signals via one of a wired and a wireless communication system, and the communication system including a communication interface with at least one of the world wide web, a cellular signal system, and a cellular paging system. 
     The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conduction with the accompanying drawings, in which like reference numerals designate the same elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial view of a pressure alarm device according to one embodiment of the present invention; 
         FIG. 2  is a combined circuit diagram and partial sectional view along line I-I in  FIG. 1 ; 
         FIG. 3  is a partial view of a pressure alarm according to another embodiment of the present invention; 
         FIG. 4  is a sectional view along line II-II in  FIG. 3 ; 
         FIG. 5  is a partial sectional view along II-II in  FIG. 3 , according to another embodiment of the present invention; 
         FIG. 6A  is a schematic diagram of one embodiment of the pressure alarm device shown in  FIG. 3 ; 
         FIG. 6B  is a partial schematic diagram of the alarm generator as shown in  FIG. 6A  containing selected alarm components; 
         FIG. 7  is a top view of a pressure alarm device according to another embodiment of the present invention; 
         FIG. 8  is partial top view of the pressure alarm device as shown in  FIG. 7 ; 
         FIG. 9  is a partial sectional view of the pressure alarm device along line III-III in  FIG. 7 ; 
         FIG. 10  is a partial sectional view of the pressure alarm device along line III-III in  FIG. 7 ; 
         FIG. 11  is a partial cross-sectional view of a pressure alarm device according to another embodiment of the present invention; 
         FIG. 12  is a top view of a pressure alarm device in an open position according to another embodiment of the present invention; 
         FIG. 13  is a partial top view of the pressure alarm device as shown in  FIG. 12  in a closed position; 
         FIG. 14  is a sectional view along line IV-IV in  FIG. 12  of a pressure alarm device in both opening and closed positions; 
         FIG. 15  is a schematic view of alternative embodiments of the pressure alarm device operationally linked with a pressure alarm communication interface, allowing wired or wireless and informational or directive communication with an external control. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In resolving the issues noted above, the present invention provides a pressure alarm device and system that overcomes the problems noted above. 
     Referring now to  FIGS. 1 and 2 , a pressure alarm device  100 , operates as at least a pressure alarm body, and includes a pressure gauge member  1  having a face  3  and a scale  4 . A needle  2  pivots on a pivot  5  relative to scale  4  during a use. An alarm sensor  6 , is one of an electrical, a mechanical pressure, a magnetic, or an optical contact trip sensor type of, and is positioned proximate a position selected by a manufacturer or customer, generally a zero reading on scale  4  below or at the plane of needle  2 . 
     Contact trip  6  operably (generally electrically) connected with an alarm circuit  7 . Alarm circuit  7  includes at least a circuit power source  8  and an alarm generator  9 . The present embodiment includes both a light  9   a  and a horn/speaker  9   b  as alarm generators  9 , but different visual, audible, electronic displays (for example to display a pager or emergency number), and even mechanical/vibratory alarm devices may be alternatively included. 
     During use, an operator operates pressure gauge  1  by opening a regulator valve (not shown) and applying a system pressure (gas cylinder pressure) to pressure alarm device  100 . The system pressure drives needle  2  around pivot  5  relative to scale  4 . The operator then operates the conventional unit (i.e. a grill or gas cylinder, both not shown) and fills an external balloon or other apparatus (both not shown) as required by a customer or operates a gas grill. 
     During continuous operation, the system pressure (gas cylinder pressure) drops and needle  2  rotates around pivot  5  relative to scale  4 . As needle  2  reaches a position proximate the preselected position, shown as a zero (0) reading on scale  4 , needle  2  trips alarm sensor  6  and completes alarm circuit  7  allowing electrical current to flow from power source  8  to alarm generator  9  (alarm devices  9   a ,  9   b , or others). 
     Power source  8  may be any type of conveniently available power source including a solar power sources or a battery-based power source, including camera, flashlight, and hearing aid type batteries or direct system power from an external source. The requirements for power source  8  are that the power supplied be adapted to operation of alarm circuit  7  and alarm generator  9 . As the focus of the present invention is on an inexpensive and portable pressure alarm device, power source  8  should be most frequently understood as a battery, but nothing herein shall prevent power source  8  from being any other type of conventional power source. 
     Adaptations to the present embodiment may additionally include an alarm circuit system controller  10  or a memory device  11  linked with and controlling alarm circuit  7 . In the embodiment shown, system controller  10  is in an operative control of alarm circuit  7  and any devices attached thereto. System controller  10  may be programmed with variables including a duration, an intensity, and a selection of any alarm given by alarm generator  9  (light  9   a , horn  9   b , etc.) or other included alarm device. Memory device  11  may be designed to retain any number of alarm variables, including the number of times trip alarm sensor  6  has actuated since a reset, and may provide an alternative-feed back loop (not shown) with system controller  10  and prevent actuation of alarm circuit  7  except during an actual pressure reduction (odd integer operations). In this manner, alarm circuit  7  will only actuate during low pressure readings of pressure alarm device  100  and not during an initial opening of pressure gauge  1  as needle  2  sweeps past alarm sensor  6  to a high pressure reading. 
     In additional embodiments, system controller  10  may be operably and controllably linked with a communications interface, for example a modem or wireless router. The communications interface may then be connected with an external control system such as the world wide web. In this manner, alternative embodiments of the present pressure alarm device may either send messages or emails of alarm or re-order or receive alarm controls from an external control, for example a home computer. 
     Referring now to  FIGS. 3 through 6B , a pressure alarm device  101 , acting as pressure alarm body  101 , includes a pressure gauge  30  having a face  32  and a scale  33 . A needle  31  pivots on a pivot  34  relative to scale  33  during a use. 
     An alarm circuit  36 , including at least a set of alarm components sensors  36   a , is positionable proximate a desired reading on scale  33 , frequently but not necessarily just above a zero reading, and includes multiple alarm generators  35  (alarm components  35 ), as will be described. Alarm circuit  36  includes at least a power source  43  and alarm generators  35 . As shown, both a light  44   a  and a horn  44   b  are included in alarm generators  35  as alarm devices, but different visual, audible, electronic, or mechanical/vibratory alarm devices may be included. 
     In the present embodiment, alarm circuit  36  includes at least a Light Emitting Diode (LED) emitter  38  and an LED receiver  39  (sensor  39 ) as alarm sensor components  36 A, but alternative combinations or substitutions of alternative alarm components may be made without changing the nature of the present embodiment. 
     Needle  31  includes a preferred sensor surface  40 . Sensor surface  40  is selected by a customer and may be one of either a reflective or an absorptive surface designed to interact with LED emitter  38  and LED receiver  39 , as will be described. Where a customer selects a conventional pressure gauge  30  for incorporation with into pressure alarm device  101 , alarm sensors  36 A may be selected for optimal effectiveness relative to the surface characteristics of needle  31 . 
     A cover system  41  suspends LED&#39;s  38 ,  39  and selected alarm components  35  in alarm circuit  36  on pressure gauge  30 . Cover system  41  includes a front cover  41 A and a back cover back  41 B. Cover system  41  surrounds a portion of pressure gauge  30 . As shown, front cover  41 A is glued to back cover  41 B and fixed, but alternative means of joining front cover  41 A and back cover  41 B may include an elastic snap joint. It should be noted that front cover  41 A is rotationally positionable and repositionable relative to face  32  before and after it is joined with back cover  41 B. In this manner, a user may select or reselect a desired ‘zero’ position for alarm sensors  36 A. 
     Those skilled in the art will readily recognize the benefits afforded by the present invention since cover system  41  (and respective front and back covers  41 A,  41 B), which allow pressure alarm device  101  to be easily adapted to preexisting pressure gauges  30  without destruction. Since the present invention does not require replacement of pressure gauges  30 , additional economic benefits and convenience exits. 
     Those skilled in the art should additionally recognize that the present cover system may alternatively include multiple ways to secure and repositionably position sensors and emitters on the pressure gauge. One envisioned embodiment for the cover system provides a front cover alone with extending retaining arms reaching to a back surface of the pressure gauge and holding the front cover in position. 
     A threaded member  42  operably joins pressure gauge  30  to an external system pressure, from a gas cylinder or boiler type unit, and allows pressure gauge  30  to operate. 
     As shown, alarm components  35  are positioned and retained, at least partially, in a portion of cover system  41  for easy visual, audible, or vibratory perception by a user. Alternatively, alarm components  35  may be positioned throughout pressure alarm device  101  where convenient for a manufacturer or user. 
     Alternative embodiments of the present invention may also include alarm components  35  of any manner best able to gain the immediate attention of a user. As examples, an alternative cover  41 C may contain alarm components  35  alternatively include LCD displays  44   c ,  44   d , covering all or a portion face  32 , and provide a message to a user (for example, instructions to call a pager or emergency number). This type of warning message may include some type of notice, or warning, or instruction to a user regarding the state of the read pressure. 
     As noted above, during use an operator operates pressure gauge  30  by opening a regulator valve (not shown) and applying a system pressure (gas cylinder pressure or boiler system) to pressurize alarm device  101 . In the case of a balloon cylinder, the operator then operates a conventional filling adaptor (not shown) and fills an external balloon or other apparatus (both not shown) as required by a customer. In the case of an LB type cylinder, the operator then conventionally operates a grill or heating apparatus. In the case, where the one of the present embodiments reads on a boiler system, the operator operates the boiler. 
     During continuous operation, the system (gas cylinder or boiler) pressure drops and needle  31  rotates around pivot  34  relative to scale  33 . As needle  31  approaches a zero ( 0 ) reading on scale  33 , sensor surface  40  on needle  31 , interrupts a signal emitted from LED emitter  38  to LED receiver  39  and completes alarm circuit  36  allowing electrical current to flow from power source  43  to alarm generators  35  (devices  44   a ,  44   b ). 
     Power source  43  may be any type of conveniently available power source including solar power sources or batteries including miniature camera, flashlight, hearing-aid type batteries, as well as direct line current. The main requirement for power source  43  is that the power supplied be adapted to effectively operate alarm circuit  36 . 
     As noted above, since the focus of the present invention is on an inexpensive and portable pressure alarm device, power source  43  should be most frequently understood to be a battery, but nothing herein shall prevent power source  43  from being any other type of suitable power source recognizable by one skilled in the art. 
     Adaptations to the present embodiment may additionally or alternatively include incorporating an alarm loop system controller  45  and a memory device  46  in alarm circuit  36 . 
     Where, alarm circuit  36  includes system controller  45 , system controller  45  is in an operative control of alarm loop  36  and any devices attached thereto. System controller  45  may be programmed with variables including, but not limited to, the duration and intensity of any alarm given by alarm generators  35  (light  44   a , horn  44   b , or an alternative eccentric vibrator (not shown)). Memory device  46  may retain the number of times control loop  36  has actuated as well as other information, and in an alternative feed back loop with system controller  45  and memory device  46  (not shown), may prevent actuation of alarm circuit  36  except during odd integer operations. In this manner, alarm loop  36  would only actuate during a low pressure reading of pressure alarm device  101 , not during an initial opening of pressure gauge  30 . 
     In an additional embodiment, system controller  45  may additionally include means for communicating with a communications interface (shown later), for example a microprocessor and a modem (wired or wireless) or a router. The communications interface may thereafter be configured to communicate with an external controller for example a personal computer. In this manner, the system controller  45  of the present embodiment may send as an alarm an email message and/or a restocking order from a supplier. In either case, memory device  46  may additionally store email addresses and other software elements necessary to send and alarm notices. It is envisioned that an additional embodiment to the present invention include means, through system controller  46  to remotely update or reset alarm signals via the world wide web. 
     Referring now to  FIGS. 7 through 10 , a pressure alarm device  102  includes a pressure alarm body  102 A joined with a pressure gauge  60  by an elastomeric member  70 . Pressure alarm body  102 A includes a rigid body  67  and opposing body arms  68 A,  68 B. Body arms  68 A,  68 B extend from rigid body  67  and provide a smooth stabilizing surface between pressure gauge  60  and rigid body  67 . Pressure gauge  60  includes a face  62  having a scale  63 . A needle  61  pivots about a pivot  64  relative to scale  63 . 
     Elastomeric member  70  surrounds pressure alarm body  102 A and pressure gauge  60  and elastically urges rigid body  67  and body arms  68 A,  68 B into close contact with an outer circumference of pressure gauge  60 . The present embodiment may be easily rotationally positioned around the outer circumference as desired, and even removed and repositioned on conventional pressure gauges. Consequently, the present embodiment is convenient to use and does not require costly replacement of conventional pressure gauges. 
     A sensor arm  66  extends from rigid body  67 , and is conveniently made from any type of translucent or transparent rigid material, for example Lexan® or polycarbonate, but maybe opaque depending upon manufacturer or customer desires. It is sufficient that sensor arm  66  retain sensors and be conveniently positionable in a desired location. Sensor arm  66  extends toward pivot  64  and cantilevers slightly above a top gauge surface of pressure gauge  60 . 
     At least one alarm sensor  65  is positioned in sensor arm  66  and is one of an optical intensity and a reflective-type sensor capable of determining a position of needle  61  relative to alarm sensor  65  against a background intensity or reflectivity of face  62 .  FIG. 8  indicates an embodiment including multiple alarm sensors similar to the previous embodiments.  FIG. 10  indicates an embodiment having a single alarm sensor  65 . In any embodiment, an operator skilled in the art will readily recognize the interchangeable nature of alarm sensors  65  depending upon commercial demand, cost, and the design of face  62  in pressure gauge  60 . 
     An alarm circuit  71  includes one or more alarm circuit leads  71 A extending from selected alarm sensors  65 . Alarm circuit  71  includes alarm generating components  69 , namely a light emitter  69 A (single or multiple LEDs or an LCD display capable of displaying a message), an audio emitter  69 B (horn or speaker), and a power source  69 C. Alarm circuit  71  may additionally include a system controller and a memory device similar to those described before, both not shown, performing similar system control and memory support functions in manners as would be commonly understood by one skilled in the art of system control. As with each of the above embodiments, power source  69 C may alternatively be an external power supply, a battery-based power supply, or some form of solar cell power supply. As with each of the above embodiments, the alarm circuit  71  may be controlled or updated by the system controller via the world wide web. The system controller is also enabled to send alarm messages and/or re-order or re-stocking emails to a designated supplier of the gas cylinders, or in the case of a boiler, may email a repair person to refill the liquid boiling medium. 
     Referring now to  FIG. 11 , a pressure alarm device  103 , alternatively pressure alarm body  103 , includes an adapted pressure gauge  80  having a scale  83  on a face  82 . A needle  81  pivots relative to a pivot  84 . 
     An alarm circuit  87  includes an alarm sensor  85  opposite a cover glass plate  86  in pressure gauge  80 . As described, alarm sensor  85  is an optical intensity sensor, which is capable of detecting a light intensity difference between when needle  81  is positioned over alarm sensor  85  (blocking external light sources), and when needle  81  is not over alarm sensor  85  (allowing external light sources to reach sensor  85 ). As with the other optical sensor systems noted above, a signal intensity changes based upon a position of needle and actuates alarm circuit  87  accordingly. 
     Alarm circuit  87  additionally includes alarm-generating components  89 . Alarm generators  89  include a light emitter  89 A and a horn/speaker-type audible emitter  89 B, but multiple types of additional alarm-generating components may also be includes allowing vibration, LCD display messages, email warnings, re-order messages, pager numbers to call, etc. 
     During operation, as needle  81  limits an optical intensity determined by alarm sensor  85 , alarm circuit  87  actuates alarm generators  89  and warns a user of a low-pressure status in the attached compressed gas cylinder (not shown) or in an attached boiler (also not shown). 
     As noted above, in the present embodiment, alarm circuit  87  may additionally include a system control module  88  including a system controller and/or a memory device (both not shown) as well as a power source  89 C. The system controller and/or memory device in system control module  88  incorporate each of the control and programming abilities as earlier noted. 
     Referring now to  FIGS. 12 through 14 , a pressure alarm device  200  includes a pressure alarm body  201  shaped similarly to the embodiment shown in  FIG. 7 . Pressure alarm body  201  includes a pair of support arms  218 ,  218  (alternatively body arms). An elastomeric member  219  elastically connects pressure alarm body  201  with a pressure gauge  202 . Pressure gauge  202  includes cover glass  208  opposite a face  204  having a scale  205 . A needle  203  pivots about pivot  206  relative to scale  205  during use of the present embodiment. As shown, a first alignment indicator  215 A visually marks a centerline of pressure alarm body  201  relative to a center of pressure gauge  202 . Since elastomeric member  219  enables an operator to rotatably position pressure alarm body  201  about an outer circumference of pressure gauge  202 , first alignment indicator  215 A enables the operator to accurately position alarm body  201  relative to scale  205 . An alarm sensor system  207  is positioned on a transparent sensor arm  220  pivotable about a pivot hinge  216  relative to pressure alarm body  201 . 
     During use, in an alignment step, an operator uses first alignment indicator  215 A to position alarm body  201  in a desired position on pressure gauge  202  and scale  205 . During an engagement step, an operator rotates sensor arm  220  about pivot hinge  216  into a position placing alarm sensor system  207  proximate cover glass  208 . A second alignment indicator  215 B is on a centerline of sensor arm  220  and overlays first alignment indicator  215 A in the engaged or closed position for sensor arm  220 . In this manner, an operator can easily confirm that both alarm body  201  and sensor arm  220  are co-aligned relative to a desired position on scale  205 . 
     An alarm circuit  221  joins alarm sensor system  207  with a control module  209  and alarm components  210 . Alarm components  210  include a power source  211  and a visual alarm emitter  212 , an audible alarm emitter  213 , and a alarm display (LCD)  214  similar to those described above. Control module  209  operates to control alarm circuit  221  and minimize false alarm signals. Control module  209  may additionally include an memory module  211 A, or another type of enabling memory module (not shown). 
     The present embodiment additionally includes alarm display  214  operably linked to alarm circuit  221  and alarm sensor system  207 . Alarm display  214  is an LCD-type display capable of displaying both an alarm signal, a pager or alarm number to call, or basic instructions or feed-back, for example, that an email-order has been placed or alarm email sent. It will be readily understood by those skilled in the art, that alarm display  214  may be operably or alternatively combined with visual alarm emitter  212  as a back-light for the LCD display, or may remain separate allowing alarm display  214  to display a predetermined alarm message or warning with an adjacent blinking light (visual alarm emitter  212 ). 
     As shown, alarm sensor system  207  is positioned on sensor arm  220  with an offset  217  predetermined by a manufacturer. Offset  217  is the selected number of degrees, relative to pivot  206 , which separates alarm sensor system  207  from alignment indicators  215 . 
     Offset  217  allows an operator to conveniently align alignment indicators  215 A,  215 B on the zero reading of scale  205  while maintaining a predetermined safety offset (for example, five (5) degrees or 5 psi). Consequently, an operator receives a low-pressure warning alarm prior to completely emptying a pressure cylinder. 
     It should be additionally understood, that control module  209  may be oparably connected with a communications interface, such as a modem or electronic router. The communications interface may in turn be connectable with an external controller, for example a home computer or other microprocessor. In this manner, the present embodiment may send alarm or instructive message, or receive controlling data similar to the above-described embodiments. 
     Referring now to  FIG. 15 , schematic descriptions of alternative embodiments of the present invention each provides a pressure alarm system  300 ,  300 ′, and  300 ″ respectively adapted to a gas cylinder  301 , an LP gas cylinder  301 A, and a boiler or hot water heater  314 . Each of the previously disclosed embodiments of the present invention may be alternatively represented by pressure alarm systems  300 ,  300 ′, and  300 ″, which are used a representative pressure alarm systems adapted to various employment environments. In each representative embodiment, a pressure alarm body  302  is operably joined to or provided integrally with a pressure gauge  303 , as earlier discussed. 
     Each pressure alarm system  300 ,  300 ′,  300 ″ is in electronic (wired or wireless) communication with a communications interface  313  via respective communication pathways  315 ,  315 ′, and  315 ″. Communications interface  313  communicates electronically with an external control via communication pathway  316 , as will be described. 
     Where pressure alarm system  300  is adapted to a Helium containing-type gas cylinder  301 , pressure alarm system  300  includes a pressure stem  307 , threadably and securely mating with gas cylinder  301 . Conventional mating connections between gas cylinder  301  and pressure stem  307  may be alternatively used. Pressure stem  307  extends to a pressure control manifold section (shown but not numbered) and a pressure diaphragm  304 , used in accessing and releasing a compressed gas retained in gas cylinder  301 . A singular or multiple male pressure fittings  306  (here shown with two pressure fittings  306 ,  306 ) extend from pressure stem  307  proximate pressure alarm body  302 . 
     In the present embodiment of pressure alarm system  300 , any of the previously described pressure alarm embodiments may be adapted for use in registering the operable pressure within pressure stem  307  and gas cylinder  301 . Male pressure fittings  306 ,  306  may be provided singularly or on a multi-headed stem depending upon manufacturer and customer desire and may be adaptable to a variety of pressure containers of differing designs. For example, pressure containers may include mylar balloons, rubber balloons, double layer balloons (with an inner balloon and an outer balloon), advertising displays, and other pressure containers having various pressure fittings that may require different male pressure fittings to fully inflate. 
     In another alternative embodiment, gas cylinder  301 A is a propane (LP) gas cylinder  301 A suitable for use with an out-door grill (not shown). In this embodiment, a pressure stem  307 ′ extends from a control valve  312 . In this embodiment, pressure alarm system  300 ′ is positioned between control valve  312  and a quick disconnect fitting  311 . Conventionally, an additional safety and carry shield  310  surrounds and protects pressure stem  307 ′ and control valve  312 . In use, a braided metal hose (not shown) connects via fitting  311  and operably joins LP gas cylinder  301  to a grill or outdoor heating device (both not shown). 
     In yet another alternative embodiment, gas cylinders  301 ,  301 A are replaced with a boiler/hot water heater  314  having an alternative pressure stem  307 ″ extending outside an operational surface of boiler  314 . A portion of pressure stem  307 ″ extends into a pressure stem fitting  307 A joining pressure stem  307 ″ with pressure alarm system  300 ″, as shown. One skilled in the art of pressure measurement will also recognize that the alternative fitting arrangements may be created to supply system pressure to the pressure alarm system  300 ″. 
     In the present embodiment, pressure alarm systems  300 ,  300 ′,  300 ″ are adaptable to include each of the alternative pressure alarm systems described above depending upon manufacturer or customer need. The present embodiment provides a simple pressure alarm system  300 ,  300 ′, and  300 ″, which are easily adaptable to a variety of gas cylinders  301 ,  301 A, or boilers  314 . 
     In each embodiment shown in  FIG. 15 , pressure alarm systems  300 ,  300 ′, and  300 ″ each including pressure alarm bodies  302  are each operably connectable with related communications interface  313  via respective electronic communication pathways  315 ,  315 ′, and  315 ″, as shown. Pathways  315 ,  315 ′,  315 ″ may be either wired or wireless pathways known to those skilled in the art of electronic communication, and communications interface  313  may be any type of known interface enabled to receive electronic signals from system controllers (not shown) each existing within respective pressure alarm systems  300 ,  300 ′, and  300 ″ and transmit the same to an external control  317 . Similarly, in operation, external control  317  may receive and send instructive signals to alarm systems  300 ,  300 ′, and  300 ″ via wired or wireless communications interface. For example, alarm systems  300 ,  300 ′, and  300 ″ may both generate an alarm signal via a display and simultaneously send a pager or email alarm to external control  317 . The external control  317 , upon receiving the alarm signal, may generate a responsive control signal, for example an instruction to order a replacement gas cylinder or to perform maintenance of some kind, and send it back to respective alarm systems  300  via communications interface  313 . 
     In each of the above embodiments, the present invention enables several forms of easily perceived visual, audible, electronic, or vibratory signals immediately adjacent the pressure gauge, or communicated electronically. Consequently, each of the embodiments provides a simple way to notify an unsophisticated or untrained operator of the need to order or locate a replacement compressed gas cylinder prior to actual pressure loss, while enabling alarm notice or re-order/resupply directions to a more sophisticated owner or operator. 
     Another benefit of the present invention is that the embodiments are alternatively adaptable for either complete replacement of a conventional pressure gauge with one of the embodiments having pressure alarm devices incorporating a pressure gauge, or simply adapting a pressure alarm device to an existing conventional pressure gauge. In either case, due to the ease of replacement or attachment, the present invention enables an inexpensive way to improve operator awareness. 
     Where one embodiment of the present invention is joined to a conventional pressure gauge, with an elastomeric member or in a cover system, the present invention allows an operator to rotationally position the pressure alarm system or pressure alarm body in a desired location relative to a pressure scale and needle. Consequently, an operator can actuate a low-pressure alarm at any desired pressure level depending upon a supplier&#39;s lead-time. For example, an operator may set the pressure alarm to operate at a 40 psi level where supply lead times are several days and may operate at a 5 psi level where supply lead times are a few hours. In either case, the present invention allows an operator to adapt the pressure alarm device to their existing situation for maximum convenience. 
     One skilled in the art of electromechanical alarm design should readily recognize that the alignment arms discussed operate as support and guiding arms or members to stabilize the alarm body relative to the pressure gauge and may be readily replaced with alternative structures providing an equivalent result in an equivalent way. 
     Additionally, multiple methods of joining front and back covers together while permitting relative exist and are adopted herein, including adhesive-based and spring-based methods. One particularly useful method of snap-joining two covers includes a male/female snap portion on respective front and back covers. As the covers are closed about the pressure gauge, the covers snap together yet are relatively rotatable allowing a position sensor to be repositioned as needed. 
     While the present disclosure reviews various types of alarm signals, including visual (instructional alarm and/or directive type alarm), audible, electronic messaging (a notice or re-order message or both), and mechanical signals, one skilled in the art of alarm signal generation should recognize that multiple alternative methods of generating alarm signals exist. It should be further recognized that the present invention permits multiple combinations of alarm signals, i.e. visual/audible, audible/mechanical, electronic/audible, etc. 
     While the present invention may draw particular attention to a defined pressure alarm body, an alarm unit, or an alarm component, these phrases should be understood as generally interchangeable types of alarms mechanisms and alarm containers (including audible, visual, and mechanical alarms) by those skilled in the art as long as the invention, as disclosed in the multiple embodiments provided, is capable of determining a desired or selected alarm/needle position and providing an associated alarm signal. 
     Alternative embodiments of the present invention may also include a specially adapted cover member, containing all the elements of a sensor/alarm circuit that snap fits or otherwise adaptively attaches to a face of a conventional pressure gauge. In this manner, the present invention may be retrofitted to existing pressure regulator gauges and eliminate the problems noted above while not requiring purchase of a new pressure regulator gauge and the trouble associated with retrofitting existing conventional control systems. 
     In the claims, means- or step-plus-function clauses are intended to cover the structures described or suggested herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, for example, although a nail, a screw, and a bolt may not be structural equivalents in that a nail relies entirely on friction between a wooden part and a cylindrical surface, a screw&#39;s helical surface positively engages the wooden part, and a bolt&#39;s head and nut compress opposite sides of at least one wooden part, in the environment of fastening wooden parts, a nail, a screw, and a bolt may be readily understood by those skilled in the art as equivalent structures. 
     Although only a single or few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiment(s) without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included without departing from the scope or spirit of the invention as defined in the following claims.