Abstract: A pressure sensor, such as the type of sensor used in screw-type refrigeration compressors, permits sensing of positive as well as negative pressures and provides an indication of the direction in which the compressor is rotating. Negative pressure leads to system shut-down, while positive pressure verification will allow compressor operation to continue. The pressure sensor includes a pair of adjustable tension springs, on opposite sides of the diaphragm, to vary the position of the diaphragm within its mechanical stroke. By establishing a pressure range of interest, and by employing an electrical sensor, such as a Hall effect sensor, the direction of movement of the diaphragm and sensor can be monitored immediately upon compressor start-up.

Abstract: A device for measuring physical values, each as pressure changes, includes a sensor transponder section and an interrogator receiver section for transmitting interrogation signals including a power supply from the interrogator receiver section to the sensor transponder section and for transmitting measured signal values in the opposite direction. The sections can be coupled to each other by inductive coils so that electrical connections are avoided. Thus, the pressure in a rotating automobile tire can be measured, for example. The sensor transponder section includes a computer circuit the input of which receives a reference frequency signal and a measured frequency signal. A reference oscillating signal has a frequency determining element that is not influenced by the pressure to be measured, but only by extraneous, e.g. environmental influences. A measuring oscillating circuit has a frequency determining element that is responsive to the changes in the physical value to be measured.

Abstract: A monitoring and alarm system allows a firefighter to monitor a variety of safety related parameters during firefighting activities through audible and/or visual means. The system monitors the pressure in the firefighter's breathing system and also monitors ambient temperature and motion of the firefighter. An audible alarm is activated to indicate a potential emergency situation relating to low remaining air time, impending thermal breakthrough or lack of motion of the firefighter.

Abstract: An ultra low pressure flow sensor consisting of a support gasket defining a flow way and having a thin, pliable membrane extending thereacross with right angle slits formed totally across the flow way portion. An electrical conductor strip is then bonded across each pair of opposing quadrants of the membrane in continuous connection to an electrical indicator circuit. The conductor strip across each pair of membranes is centrally notched to a preselected depth of cut thereby to adjust the flow pressure break strength.

Abstract: A differential pressure control provides a housing having a pair of opposing inlets for accepting lines having different fluid pressures therein. The inlets are sealably connected to a central chamber having a piston by means of diaphragms. The piston is joined to a pivoting lever having a free end that translates as the piston is moved by each of the diaphragms. Upon existence of a pressure inbalance, the free end is moved by the piston, tripping a switch that indicates the pressure imbalance. The lever includes an adjustable spring to vary the gain of the switch and further includes a pair of opposing stops that limit the lever's displacement to substantially match that of the throw of the switch.

Abstract: A pneumatic pressure detector for use in an overheat or fire alarm system utilizes a known capillary type sensor tube which has absorbed in it a gas. Overheat or fire condition causes the gas to expand which then actuates an associated deformable diaphragm to close an electrical switch. To insure that the system pressure is maintained and no fault condition exists, the compact detector also uses a deformable diaphragm associated with an integrity switch which opens if the pressure falls below normal. Both of these diaphragms are juxtaposed to form the plenum to which the sensor tube is attached thereby saving weight and space.

Abstract: A pressure sensor that responds to a predetermined rate of change of pressure in the fluid medium comprises a housing that encloses a pressure chamber which has a divider wall that consists of a printed circuit board and a flexible diaphragm which is permeable. The divider wall serves to separate the pressure chamber from the pressure sensitive system in which the sensor is used. The sensor may be used in a pneumatic tire and in such use the flexible diaphragm will be deflected to activate a transmitter when the pressure in the tire changes at a hazardous rate. The sensor will not activate the transmitter when the rate of change of pressure is less than a hazardous rate of change.

Abstract: An orthopedic exercise chamber such as a slipper including a light-weight, self-contained limb load monitor is disclosed. The limb load sensor circuit provides extended service life for the miniature power supply that is included in the slipper, thereby making the slipper suitable for out-patient use. A fluid-filled plantar chamber that supports the entire load borne by the patient's foot is connected to the sensor circuit, thereby providing improved monitoring of the load being carried by the leg or foot that must be protected from excessive loading.

Abstract: An oil-pressure warning apparatus for automobiles includes an oil-pressure switch which is turned on when the circulation pressure of engine oil drops below a predetermined level, an alarm circuit which provides an electrical path in response to the on-off operation of the oil-pressure switch, and a warning control circuit which energizes the alarm circuit when the oil-pressure switch is turned on and maintains the energization of the alarm circuit. Thus, even when the oil pressure switch fluctuates back and forth between its on and off positions, the warning lamp will not flash.

Abstract: An oil filter for filtering oil is combined with a differential pressure indicator with temperature compensation. The differential pressure indicator has a spool assembly slidably disposed in a spool insertion cylinder in axially confronting relation to a terminal which is connected through a warning lamp to a battery. The spool assembly comprises a spool body disposed for axial sliding movement in the spool insertion cylinder, a contact member disposed for axial sliding movement in the spool body and having a contact pin movable out of one of the spool body, and a spring of a shape-memory alloy, restorable to a memorized shape when the oil is in a predetermined temperature range, for biasing the contact member to move the contact pin out of the spool body towards the terminal. When a differential pressure in excess of a predetermined level is developed in the oil and applied to the spool assembly, the differential pressure acts to move the spool assembly towards the terminal.

Abstract: A pressure sensor that responds to a predetermined rate of change of pressure in the fluid medium comprises a housing that encloses a pressure chamber which has a permeable wall and flexible diaphragm that separates the pressure chamber from the pressure sensitive system in which the sensor is used. The sensor may be used in a pneumatic tire and in such use the flexible diaphragm will be deflected to activate a transmitter when the pressure in the tire changes at a hazardous rate. The sensor will not activate the transmitter when the rate of change of pressure is less than a hazardous rate of change.

Abstract: A pressure responsive apparatus having an encoded disc provides preselected pressure indication. The apparatus preferably includes a pressure gauge having a Bourdon tube responsive to an external pressure. The Bourdon tube drives a conventional pointer indicator which has mounted thereto the encoded disc. Light is transmitted to the disc by means of fiber optic cables from a remotely positioned oscillator. Light if reflected by the disc at the preselected pressures and transmitted by fiber optic cables to processing circuitry that responds to reflected light signals as generated by the oscillator. To generate these light signals, light emitting diodes form a light source and the light signals are detected by means of phototransistors. For apparatus detecting two preselected pressures, there is a light source/light detector pair for each pressure. The processing circuitry responding to the outputs of the phototransistors generates visual indications of the preselected pressures.

Abstract: A modular self-contained mechanical refrigeration unit adapted to form one wall of a refrigeration appliance is relatively thin and includes all of the electrical, mechanical and control components of the sealed refrigeration system.

Abstract: A pressure transducer having a first pair leads for receiving an excitation voltage and a second pair of leads between which it can supply a voltage corresponding to a pressure applied to it is provided with means for placing at least one electrical load between said first pair of leads. The leads are connected to a pressure monitor having means for indicating the pressure represented by the voltage between said second pair of leads and means for indicating an alarm condition when said signal indicates a pressure outside of a given limit. The monitor has local means for disabling the alarm indicating means and means for setting the indicated pressure to zero. The monitor also has means responsive to a first given current in said first pair of leads for disabling said means for indicating an alarm and means responsive to a second given current in said first pair of leads for causing said means for indicating pressure to indicate a zero pressure.

Abstract: A method of detecting failure to tighten screws against works includes steps of detecting every screw tightening operation against a work after start of a screw tightening step, counting the number of times of the screw tightening operations detected in the previous step, detecting the completion of the screw tightening step, and comparing a counted value at the time of the completion of the screw tightening step with a predetermined value, thereby informing of a result of comparison.

Abstract: A vacuum pressure monitoring system includes a mercury manometer in communication with a vacuum line from an apparatus operating under high vacuum (approx. 0.25 in. Hg). A proximity sensor targets the height of the Hg. Incremental changes in the height of the Hg are detectable by the proximity sensor which triggers safety control components for alerting personnel and for protecting the apparatus.

Abstract: An improved apparatus for monitoring a respiratory circuit comprises two independent pressure sensing means, a first pressure sensing component having a preset minimum pressure for creating an alarm condition in response to pressure falling below the minimum, and a second pressure sensing component having an adjustable low pressure threshold setting means and for creating an alarm condition if the patient's breathing cycle pressure fails to periodically pass through the low threshold pressure. A preferred embodiment includes visual pressure indicating means including a display of the low threshold pressure setting and a display of the patient's breathing cycle pressures.

Abstract: By providing pressure-responsive switch-actuation means constructed for being substantially unaffected by temperature changes, a pressure sensor is attained which is capable of monitoring pressure levels with precision, regardless of the ambient temperature to which the system is subjected. By employing temperature insensitive material to effectively compensate for temperature changes incurred by the remaining sensor components, the actuation control assembly of the sensor is capable of achieving precision monitoring of desired pressure levels regardless of changes in the ambient temperature to which the monitor assembly is exposed. In one preferred embodiment, the pressure sensor of the present invention incorporates a uniquely constructed, machined bellows which further enhances and provides precision pressure sensing capabilities.

Abstract: A pressure sensor that responds to a predetermined rate of change of pressure in the fluid medium comprises a housing that encloses a pressure chamber which has a permeable wall and flexible diaphragm that separates the pressure chamber from the pressure sensitive system in which the sensor is used. The sensor diaphragm will be deflected to activate a transmitter when the pressure in the tire changes at a hazardous rate. The sensor will not activate the transmitter when the rate of change of pressure is less than a hazardous rate of change.

Abstract: A sewer blockage alarm for a sewer line having a pressure sensor mounted at the top of a clean out branch section of the sewer line which is connected to a large diameter pressure multiplying pressure bell via a length of flexible to be dangled at the entrance of the branch section. An audible and a visual indicator are activated by slight pressure rises caused by water level rising to the tip of sewer line to provide an early warning of an incipient blockage condition.

Abstract: An apparatus for determining the rate of discharge from a nozzle for spraying an aqueous solution of hydrogen peroxide comprises a pressure sensor for detecting the internal pressure of a pipe for supplying the solution to the nozzle under elevated pressure, and means for determining the rate of discharge from the pressure detected by the pressure sensor and the predetermined relationship of the discharge rate of the nozzle with the internal pressure of the pipe.

Abstract: An improved collective protection system (CPS) alarm is generally comprised f an electronic circuit board terminal box that is readily connectable to any selected point of a ship power bus system. The system is provided with a plurality of pressure transducers that are selectively disposed in associated remote zones to be continuously monitored. A master monitoring panel is connected to the terminal box and is provided with a pressure indicating meter and a series of three red, yellow, and green lights corresponding to each remotely monitored zone. Separate slave panels allows monitoring of light status at additional locations such as a pilot house and/or a damage control station. The system is appropriately shielded to prevent EMI or RFI interference.

Abstract: This invention discloses a truck with a hand-operatable bed of which the front side under surface is provided with a pair of front wheels and of which the rear side under surface is supported by a hydraulic cylinder, for lifting or lowering the bed, mounted on a pair of rear wheels by means of bearings, which is characterized by being further provided with an overload-sensing device and an alarm-raising device to be put into operation according to the sensing of the overload-sensing device. Because operators can be told about an overload immediately by the devices, they do not have to keep a plunge pump working without being aware of an overload applied on the cylinder as did before. What is more, as they can realize whether the cause of not feeding oil to the cylinder has come from troubles in pressure lines or an overload, they can take measures against the cause at their earliest possible, with the result that the safety and the operatability in handling the truck are improved greatly.

Abstract: The invention discloses a method and an apparatus for explosion protection of plants, pipelines and the like by monitoring chronologically successive values of the system pressure in the potentially explosive area and by comparing these values with a predetermined pressure threshold, where the exceeding of this pressure threshold is used as a triggering criterion for initiating explosion protection provisions. According to the invention, instead of predetermining a constant value as the pressure threshold, the pressure threshold is updated continuously in accordance with the system pressure prevailing at that time. As a result, the pressure threshold can be set with a smaller safety margin above the system pressure than before. Brightness and temperature thresholds may also be used singly, or together with pressure in any combination in continuous value monitoring.

Abstract: A pair of electrical switches are operable by a movable lever between a first condition where the first switch is on and the second switch is off, to a second condition where the first switch is off and the second switch is on, by movement of a piston connected to a pressure source via an inlet port. A flange is fixed on the piston shaft, and a compressed spring is mounted over the piston shaft between the flange and a sleeve surrounding the piston bore. A pressure close to ambient moves the flange which in turn moves the lever to the first position, while a pressure substantially less than ambient moves the flange in the direction to move the lever to the second position. The switches are adapted to respond to the pressure of the input manifold of a motor vehicle, actuating the vehicle headlight circuit when the motor is running and the manifold pressure is very high, and actuating the starter/ignition circuit when the motor is not running and the manifold pressure is at ambient.

Abstract: The invention is concerned with switch devices and more particularly with devices to be fitted to piston and cylinder actuators to monitor the position of the piston therein. The device comprises a switch which has two connection or terminal contacts arranged at its axially opposite ends. These terminal contacts are respectively connected with signal conductors which may for instance be in the form of flexible cable wire. The switch is accommodated in a sleeve surrounding it. The two signal conductors are extended as far as a common axial terminal or connection end of the switch. For producing an electrical connection of the one signal conductor with the second terminal contact the current is caused to flow through the sleeve.

Abstract: A pressure gauge has a turning button, a turning disc and a sliding block disposed thereon that, through a protruding wheel fixed on the needle shaft moves the sliding block to force a contact point of a conducting metal piece to contact with a contact point of the turning disc, can start an alarm in case the needle of the gauge comes to reach the designated pressure.

Abstract: An air sampling and alarm control system for detecting the presence of a toxic contaminant in the atmosphere and for providing an audible alarm when insufficient gas flow is present in the system to adequately test for the presence of the contaminant. The alarm control is provided by a pressure switch which is electrically connected in circuit with an audible alarm and pneumatically connected in circuit with the gas flow line connecting the sampling pump to the sampling detector.

Abstract: Method and system for detecting a level of an engine oil of an engine include an operation for detecting a time duration in which the engine is operating. When the engine operation has continued for more than a predetermined time period, and the engine is stopped subsequently, the oil level is detected after the elapse of a second predetermined time period in which the engine is stopped. By this feature, the engine oil level is detected very accurately.

Abstract: A proximity switch for signaling the location of a movable member at either of opposite end limits of movement relative to a stationary frame includes a movable member, such as a piston, traveling along a fixed path of movement between a first position and a second position and having an aperture formed within the movable member extending from one end toward another end. A housing encloses a portion of the movable member to form a first fluid chamber between the movable member and a first end of the housing, and to form a second fluid chamber between a second end of the housing and the movable member. Expansion of the first fluid chamber drives the movable member to the first position and expansion of the second fluid chamber drives the movable member to the second position.

Abstract: Disclosed is an engine fuel flow restriction warning system comprising an engine including a first conduit means connecting a fuel storage means and a fuel pumping means. A second conduit means connects a fuel pumping means with an engine fuel inlet means. Pressure sensing means communicates with the first conduit means, and the pressure sensing means operates a warning means to produce a warning when the pressure in the first conduit means reaches a predetermined low level. When used with an engine including a cooling system and a cooling system temperature sensing means communicating with the engine cooling system, the temperature sensing means operates the same pressure warning means to produce a warning when the temperature in the engine cooling system reaches a predetermined level.

Abstract: Monitoring a room is accomplished by measurement of air pressure where air passage resistance between a secured room and an outside atmosphere is measured and an alarm actuated, if the air passage resistance drops below a predetermined value. Evaluation of typical air pressure fluctuations in a frequency range between 0.01 Hz and 10 Hz is advantageous. The air pressure resistance may be determined by difference measurements of air pressure fluctuations in the outside atmosphere and the secured room, or as a singular process wherein a connecting tube is provided between the room to be secured and the outside atmosphere, where air movements varying as a function of air pressure fluctuations are measured. Devices for the carrying out of the process are described. The devices and the process provide a simple and cost effective alarm system that operates reliably and is secure against outwitting and sabotage.

Abstract: A medical pumping system has a supply tube (2), an outlet tube (6), a readily sterilizable, disposable cassette (3) connected to the tubes and engaged with the pump, and means (22,24) such as a motor-driven piston, for intermittently applying pressure to the cassette. The pumping system features a display and switch means (9, 10) on a front panel thereof, a pressure sensor (28), an optical fluid presence sensor (19), and a microprocessor (20) metering the volume of fluid pumped through said cassette (3), monitoring output signals from said sensors (18, 28), controlling the motor-driven piston in accordance with settings entered via said switch means (9,10), and directing output data to said display means (8). The microprocessor has a stored program for performing SET RATE, RUN, HOLD, VOLUME FED, and CLEAR VOLUME functions.

Abstract: Apparatus is provided to evacuate an air-tight openable and closeable container to a sub-atmospheric pressure. A flexible diaphragm inside the container responds to a change in pressure to actuate an alarm. In one embodiment, a display case is evacuated via a one-way valve by connecting a pump thereto. In a different embodiment, a pump inside a hand-carried case evacuates the case via a one-way valve. Alternatively, at least one side of the case is flexible enough to evacuate the case by pushing thereon, with no pump being required.

Abstract: An immersion control device. The device includes a fluid filled manifold and a fluid filled support device. Fluid pressure in the fluid filled support device equals fluid pressure in the fluid manifold notwithstanding respective fluid volumes. Immersion depth is controlled by increasing or decreasing fluid pressure. A fluid pressure regulator operates manually or automatically in response to a feedback of a fluid pressure change. Regulating members and spaced apart conductors or conductive stages can be used to provide feedback and activate an alarm, the fluid pressure regulator or both.

Abstract: An electronic oil pressure transducer circuit interfaces a piezoresistive pressure sensor to magnetic needle movement and lamp or electronic instrument control computer for reliable automotive engine oil pressure instrumentation. Circuit design uses standard components suited for automotive under-hood environment. Calibration is performed at the design level, eliminating the need for expensive on-line procedures. Circuit assembly is designed for automated, high-volume production.

Abstract: An electronic relay control circuit is provided for liquid cooled electric power transformers. The control circuit senses the rate of change of internal tank pressure and operates its relays in response to a sudden pressure increase. Relay control connections are provided for operating transformer trip and annunciator circuits. The relay response is field adjustable.

Abstract: An apparatus for detecting when bolts, holding coacting surfaces of two objects together become loose. A gas supply is connected to a gas passageway in one of the bodies which extends to the coacting surfaces. A gas reservoir is positioned downstream of the gas supply and a flow orifice is connected to downstream of the reservoir. A pressure measuring switch is connected to the gas passageway and is actuated upon a drop of gas pressure to a predetermined value. An alarm is connected to the switch and when actuated provides an indication of the separation of the coacting surfaces.

Abstract: A proximity switch for signaling the location of a movable member at either of opposite end limits of movement relative to a stationary frame includes a movable member, such as a piston, traveling along a fixed path of movement between a first position and a second position and having an aperture formed within the movable member extending from one end toward another end. A housing encloses a portion of the movable member to form a first fluid chamber between the movable member and a first end of the housing, and to form a second fluid chamber between a second end of the housing and the movable member. Expansion of the first fluid chamber drives the movable member to the first position and expoansion of the second fluid chamber drives the movable member to the second position.

Abstract: An improved ventilator monitor and alarm apparatus includes circuit means for actuating the apparatus in response to sensed pressure in a ventilator circuit.

Abstract: The present invention concerns a method of sensing and indicating errors in a dosing circuit, in which a pumping device (1) pumps a fluid via a conduit system out to at least one dosing device (3) located nearby a dosing place. The dosing device (3) measures and discharges intermittently a predetermined volume of the fluid through a pressure controlled non-return valve (16) to the dosing place, when the pressure in the conduit system is increased from a low pressure to a high pressure during a certain limited time.

Abstract: A low pressure warning device for use by scuba divers attaches to a fitting on the high pressure stage of the air tank. The warning device has both audible and visual indicators contained in a housing attached adjacent the air pressure gauge. A two stage warning to indicate a first low pressure and a second dangerously low pressure may be provided.

Abstract: An accumulator has a piston axially slidably disposed in a cylinder mounted in a casing, the cylinder and the piston jointly defining a reservoir communicating with an inlet/outlet port in the casing. A piston rod axially movably disposed in the casing has an end slidably fitted in the cylindrical hole of the piston. The piston rod is normally urged by a spring to force the piston into the reservoir. The accumulator also includes a switch mechanism for detecting the position of the piston in the cylinder. The switch mechanism may comprise a reed switch, a light-sensitive switch, a pressure-sensitive switch, or a pushbutton switch.

Abstract: A pressure responsive switch including a case having a pressure inlet and an orifice plate, an amorphous diaphragm and a ferrite core arranged in said case, said ferrite core having a pick-up coil housed therein, in which a pressure introduced into the case acts through the orifice plate against a surface of the amorphous diaphragm and a mechanical deformation of said amorphous diaphragm caused by said pressure is detected as a variation of electrical signal by means of the pick-up coil. The characteristic feature resides in that said orifice plate has a larger area at its side facing the ferrite core than at its opposite side facing the pressure inlet.

Abstract: An improved automatic train-line air brake pressure monitoring system includes circuits that emulate an automatic brake valve and cause an automatic brake manifold release whenever a four psi increase in pressure is sensed. The system includes a pressure sensor amplifier (10) which provides a signal proportional to the sensed pressure in a brake pipe. This signal is tracked by a peak hold circuit (12) that stores the peak value of the signal. The output of the sensor amplifier is subtracted from the output of the peak hold circuit in a subtractor (14) to provide a difference signal. The difference signal is tracked by a reduction hold circuit (22) which stores the minimum value of the difference output from the subtractor. An increase in measured pressure from the stored minimum value is compared in a comparator (24) with a reference value representing the four psi level, and when the increased pressure exceeds the reference value, a system reset is generated.

Abstract: A window security device which operates on differential gas pressure theory to trigger an alarm upon pressure equalization. A plug which completes the electric activator circuit includes biasing springs or similar devices to urge the plug out of contact with the activator circuit to trigger the alarm upon disturbance or breakage of one of the window glazing panels.

Abstract: An electrohydraulic switching device for emitting electric control signals in dependence on supplied pressure signals. The switching device has a housing wherein a piston pressurizable by the inlet pressure is arranged so as to be axially displaceable. The piston is spring-loaded against the inlet pressure by means of a compression spring arranged between a spring plate and a guide means. The spring plate is secured at the piston by means of a snap ring, and the switching device has an actuating plate for actuating an electric switching mechanism. The actuating plate is positively connected with the piston, with the compression spring at its end facing the switching mechanism being axially guided by the guide sleeve.

Abstract: A device primarily for attachment to the spout of a teakettle for generating a musical signal in response to the vapor pressure of boiling water. A diaphragm distorts in response to the pressure and closes an electrical switch which applies battery voltage to a circuit in which a representation of a pre-selected tune is stored. The tune is applied to a piezoelectric speaker within a resonating housing to audibly signal the user that the water in the teakettle is boiling.

Abstract: A lightweight, free-standing, expandable shelter (10) providing protection against chemical and biological agents and against nuclear fallout. The shelter (10) has a frame comprising a series of U-shaped ribs (12) spaced and held parallel by a series of reinforcing members (16) connecting each adjacent pair of ribs (12) on each side of the shelter (10). A cover (11) made of flexible material which is resistant to chemical and biological agents is attached to the frame. An airtight floor (18) is attached to the cover material (11) so that the shelter (10) can be pressurized to a pressure of about one inch water gauge above ambient pressure, to prevent reverse air flow of contaminated air into the shelter (10). A blower (20) for pressurizing the shelter (10) and a filter (22) capable of filtering out chemical and biological agents are connected to the shelter (10).

Abstract: A pneumatically operated pressure switch for monitoring the air pressure in a tire is provided with a second switch in its housing capsule. The second switch is connected to an oscillating circuit. This second switch changes the oscillating circuit upon sensing a change in the gas pressure in the reference pressure chamber. This leads to an error indication to the driver, and thereby provides a self-monitoring pressure switch for monitoring the air pressure in a tire.