Kearflex Engineering Co.

United States

ANSI B16.5 Process FlangeThese are a very common type of flange used throughout the process industry. They bolt into the side of tanks, pressure vessels and piping systems. The flanges are available in Class 150, 300, 450 and 600, which allow operating pressures up to 1, 580 Psi.In level applications, the weight of the liquid above a point creates a pressure that is measured by the diaphragm based sensor. The density of the liquid needs to be known, and this type of measurement is suitable for liquids that are corrosive, have extreme temperature and contain solids.The flange assemblies can be liquid filled where the diaphragm isolates a delicate sense element, or direct where the diaphragm displacement is calibrated and the motion is used to measure level.ANSI Flange CutawayIsolation DiaphragmsKearflex offers a line of diaphragms specifically used for isolation applications. This is where there is a fluid fill behind the diaphragm which trasmits pressure to a remote, or "isolated" sensor. The sensor can be of any type including strain, gauge, piezo, capacitive, inductive and optic.Direct Acting SwitchIn a direct acting assembly the diaphragm displacement with respect to pressure, and therefore level, is calibrated. The diaphragm acts like a linear spring and will move a known distance with pressure, and this displacement can be converted into level.The diagram shows a simple level switch. This direct acting switch has several advantages.No Liquid Fill There is no liquid fill as used with isolation diaphragms, and therefore no possibility of contaminating a critical process in the event a diaphragm is damaged.Very Sensitive DiaphragmsA very sensitive diaphragm can be used which can detect down to a few inches of liquid. This allows quick detection if mounted in a spill containment vessel, or overfill protection if mounted at the top of a storage vessel.Alternative TechnologyThe switch is not electronic or microprocessor based - it will remain operational in the event of electrical or electronic interference, and is a suitable backup of other technologies.

FULL INSTRUMENTSAltitudePressure vs AltitudeThis instrument uses an aneroid capsule assembly to measure the atmospheric pressure outside of an aircraft.The pressure at a given altitude is a function of the air supported above that point where the force is caused by gravity. As the column of air is taller closer to earth, there is more pressure. However, this is not a linear progression due to the fact that air is compressible. Altitude Pressure Chart Altitude Pressure ChartThe Altitude Pressure Chart provides a visual representation of what the instrument must be calibrated to measure. There are only very slight changes in pressure past 30, 000 feet.The nature of an altitude instrument requires a great deal of sensitivity as the atmospheric air pressure approaches a vacuum. Aneroid CapsuleThe aneroid capsule assembly has a deep vacuum trapped inside, and measures the difference between the atmosphere outside of the aircraft, and this nearly perfect vacuum. The internal vacuum is constant and provides the reference pressure that the capsule uses to measure altitude.Temperature EffectAn important consideration is temperature. Heat reduces the density of air resulting in a lower pressure due to the force of gravity. To know the true altitude, both the atmospheric pressure and the ambient temperature would be required. This class of altitude instrument is not temperature compensated.This does not invalidate the usefulness of this instrument - the temperature of the atmosphere gets colder, and is more predictable as altitude increases above 10, 000 feet. Operating from 20, 000 to 50, 000, the instrument will be accurate.As the aircraft approaches an airport the controller will advise the "temperature altitude" at the runway. In Denver during the summer, this value can be as high as 9, 000 feet. The pilot knows that when his altitude instrument indicates 11, 000 feet, the aircraft is really 2, 000 feet above the ground.Instrument ApplicationThis type of altitude instrument is not usually used for primary flight in newer general aviation. Contemporary microprocessor based altimeters, and radar altimeters coupled with heads up and in dash displays provide for more accuracy without other considerations on the part of the pilot.These instruments remain in the aircraft for emergency use, and in the hands of a skilled pilot will still allow for a safe landing.Other applications include balloons and ultra-light aircraft where un-powered mechanical instruments would be attractive.AirspeedDifferential Pressure vs AirspeedThis instrument uses a capsule assembly to measure the differential pressure produced by a pitot static tube mounted outside of the aircraft.The pressure at a given airspeed is a function of the impact pressure of the air hitting the aircraft, and the ambient pressure surrounding the aircraft. However, this is not a linear progression due to the fact that impact force is a function of kinetic energy which has a square function. Airspeed Pressure ChartAirspeed Pressure ChartThe Airspeed Pressure Chart provides a visual representation of what the instrument must be calibrated to measure. There are only very slight changes in pressure below 50 knots. The nature of an airspeed instrument requires a great deal of sensitivity at low speeds.Differential CapsuleThe differential capsule assembly measures the difference between the impact pressure at the tip of a pitot tube, and the atmospheric pressure outside of the aircraft. If the aircraft is stationary with no impact pressure, the differential capsule will indicate zero at any altitude - this is because the ambient pressure is applied equally to both sides of the sensor.Altitude and Temperature Effect A consideration is altitude and temperature. Both heat and altitude reduce the density of air resulting in a lower impact pressure, and a reduced indicated airspeed. This class of altitude instrument is not temperature or altitude compensated.This does not reduce the usefulness of this instrument. Because the wing requires more airspeed to generate lift in less dense air, the indicated airspeed is very important - the plane will stall at the same indicated airspeed at any temperature altitude. At low altitudes during takeoff and landing, the errors are small.Glass Cockpit with legacy Altitude and AirspeedInstrument ApplicationThis type of airspeed instrument is not usually used for primary flight in newer general aviation. Contemporary microprocessor based air data computers, and radar sensors coupled with heads up and in dash displays, provide far more accuracy without other considerations on the part of the pilot.These instruments remain in the aircraft for emergency use, and in the hands of a skilled pilot will still allow for a safe landing.Other applications include balloons and ultra-light aircraft where un-powered mechanical instruments would be attractive. Vertical Speed InstrumentVertical SpeedDifferential Pressure Generated by Time DelayThis instrument uses a capsule assembly to measure the differential pressure produced by changes in altitude. The differential pressure is created by measuring two volumes - one attached directly the atmosphere outside the aircraft, and the other attached via a restrictor. The restrictor makes the second volume respond slowly to changes in pressure, which are the result of changes in altitude. This time lag is directly related to the altitude rate of change.

Mechanical MovementsMechanical movements amplify the displacement of the diaphragm to turn a pointer providing pressure indication.Specific advantages of the Kearflex Diaphragms:Ranges: 1 Psi to 400 PsiLinearity: 1% of full scaleConsistent: 1% or less variance within a lotHysteresis: 0.5% or lessMaterials:316L, Nispan, Inconel, Hastelloy, or any available material that is formable.Note:The size of the diaphragm is based pressure range.1.125 Inch Diameter: 10 Psi to 400 Psi1.375 Inch Diameter: 10 Psi to 75 Psi1.590 Inch Diameter: 10 Psi to 50 Psi2.000 Inch Diameter: 5 Psi to 50 Psi2.375 Inch Diameter: 1 Psi to 25 PsiSmall Mechanical GaugeUsing the small 1.125 inch diameter diaphragm, this mechanical gauge can be calibrated in ranges from 10 Psi to 400 Psi.A range of diaphragms is used providing the same deflection at the specified full scale pressure. This allows the mechanical movement and all other parts except the faceplate to be common for all ranges.

Aneroid CapsuleThe aneroid capsule assembly has a deep vacuum trapped inside, and measures the difference between the atmosphere outside of the assembly and this nearly perfect vacuum. The internal vacuum is constant and provides the reference pressure that the capsule uses to measure altitude.Note the collapsed condition of the altitude capsule compared to the airspeed capsule. The atmospheric pressure is pressing on the assembly which has an internal vacuum. Increasing altitude up to the near vacuum at 40, 000 feet, the capsule will expand to nearly the same profile as the airspeed assembly.Both capsules measure a differential pressure and are neutral when the difference is at or near zero. For the aneroid, this occurs when exposed to a vacuum, and for the airspeed, this occurs when the inside and the outside pressure are equal.The aneroid capsule is used in measurement of the aircraft altitude, and for the cabin pressure.Differential CapsuleThe differential capsule measures the pressure outside the assembly with respect to the inside of the assembly. It operates as an analog computer in that any pressure applied equally to both sides of the capsule will result in zero deflection.In application, an airspeed capsule measures the difference between the impact pressure at the tip of a pitot tube and the static air pressure surrounding the side of the tube. The differential capsule ignores the altitude of the aircraft because this is applied to both sides equally. A stationary aircraft at sea level or in Denver will both have a zero differential.Principal of Operation In all cases, diaphragm based capsules convert a differential pressure to a displacement. It is important to remember that an aneroid is still a differential pressure measurement, with the special characteristic being that internally this value is held at zero, or full vacuum. Mechanically, the diaphragm functions the same way in sealed and un-sealed assemblies.AneroidNote the natural direction of deflection is collapsing with the external air pressing against the internal vacuum.Differential Capsule GraphicDifferentialNote the natural direction of deflection is expanding with the internal air pressure exceeding the external air pressure. The direction of pressure application can be reversed so that the capsule would collapse on differential pressure.In addition, the higher pressure can be applied both internally and externally for a bi-directional deflection. This is how the capsule is used in the Altitude Rate of Change instrument the applied differential is used for both climb and decent, and the capsule moves in both directions. Altitude Compensated AirspeedThe altitude compensated airspeed capsule is a clever analog computer that provides a pitot static airspeed reading that is corrected for changes in altitude.Assuming that an aircraft was traveling at a constant 350 knots and went from 10, 000 feet to 30, 000 feet in altitude, the pitot static pressure would drop due to the lower density of the air at the higher altitude. This would cause the differential pressure capsule to collapse.At the same time, the smaller altitude capsule mounted on top of the differential would expand due to the lower pressures at the higher altitude. The altitude and airspeed capsules are approximately matched so that the overall travel is opposed and equal.The primary application for this assembly is in ejection seats. A single switch can be used to trip when the pilot is both below a specific altitude and a specific airspeed. The parachute must not deploy at high speed which would injure the pilot, or at too high an altitude where it would be too cold.This little analog computer is very powerful it is small and non-electronic.

Isolation DiaphragmsKearflex offers a line of diaphragms specifically used for isolation applications. This is where there is a fluid fill behind the diaphragm which transmits pressure to a remote, or "isolated sensor". The sensor can be of any type including strain gauge, piezo, capacitive, inductive and optic.The important characteristic of the remote sensor is that it is not suitable for exposure for the wetted media. The process media can be corrosive, high or low temperature and can contain solids. The key attributes of an isolation diaphragm are high sensitivity, and the material. The sensitivity allows a very thin diaphragm to pass through the applied pressure with a minimal change. The raw material is matched to the process media, and can be 316L, Hastelloy, Inconel, Monel, or any other material that can be formed into a diaphragm.Common Types Ansi B16.5 Process FlangeThese are a very common type of flange used throughout the process industry. They bolt into the side of tanks, pressure vessels, and piping systems. The flanges are available in Class 150, 300, 450, and 600, which allow operating pressures up to 1, 580 Psi.Sanitary Style FlangesSanitary Style FlangesUsed in the food processing and pharmaceutical industries, the isolation diaphragm provides a sterile sensing interface. These diaphragms include special internal angles that allow natural drainage for in place cleaning and sterilization.Industry specific surface finishes include electro-polishing, and bio-compatible coatings. These assemblies are installed using standard quick release clamps.Sandwich Clamp Design Sandwich Clamp DesignThis is a variation of the bolted flange type, except that it is clamped between flanges, or a tank flange interface, and does not include the bolt pattern in the assembly. The advantage of this approach is the assembly is significantly smaller and lighter.Custom Body ApplicationPictured is an isolation diaphragm installed in a custom body which has two ports to allow flush through cleaning. Kearflex can provide this type of assembly based upon a customer design, a clean sheet of paper approach, or a combination of both.Ansi Flange CutawayCut away view of the ANSI B16.5 Flange assembly. The chamber is filled with a liquid and pressure on the diaphragm creates pressure inside the chamber which is measured by the sense elements. The sensor can be of any type including strain gauge, piezo, capacitive, inductive, and optic.

High Pressure SwitchesKearflex utilizes a unique capsule assembly in our high pressure switches. These switches can be calibrated in ranges from 500 Psi to 5, 000 Psi and are compatible with hydraulic fluid.Applications include lubricating oil, brake and other hydraulic systems and high pressure systems.

Altitude SwitchesKearflex incorporates our diaphragms and capsule assemblies into altitude switches. In the altitude switch, the sensing element has a permanent vacuum trapped inside to allow the switch to respond to atmospheric pressure.The pressure port and housing can be configured to meet the customer needs.Airspeed Switch Airspeed SwitchesKearflex integrates our diaphragms and capsule assemblies into airspeed switches. In the airspeed switch, the sensing element applies pressure to both sides allowing measurement of the pitot and static pressure signal.The pressure port and housing can be configured to meet the customer needs.Process Monitoring SwitchesAbsolute PressureKearflex designs our diaphragms and capsule assemblies into absolute pressure (Psia) switches. In the absolute switch, the sensing element has a permanent vacuum trapped inside that provides a reference for the measurement.These are configured the same way as the altitude switches, but can be calibrated as required for Psia switch points.Applications include vacuum systems and monitoring sealed tanks such as fuel, water or waste.Differential PressureKearflex incorporates our diaphragms and capsule assemblies into differential pressure (Psid) switches. In the differential switch, the sensing element applies pressure to both sides allowing measurement of closed systems.These are configured the same way as the airspeed switches, but can be calibrated as required for differential pressure switch points.Applications include cabin pressure systems, air filter pressure drop monitoring and closed tank level monitoring.Gauge PressureKearflex integrates our diaphragms and capsule assemblies into gauge pressure (Psig) switches. In the gauge switch, the sensing element applies pressure to one side, and the other side is open to ambient.These are configured the same way as the differential switches, but can be calibrated as required for gauge pressure switch points with only one connection required.Applications include air pump output, bleed air systems and instrument supply air.

Isolation Diaphragm DesignKearflex offers a line of diaphragms specifically used for isolation applications. This is where there is a fluid fill behind the diaphragm which transmits pressure to a remote, or "isolated" sensor. The sensor can be of any type including strain gauge, piezo, capacitive, inductive and optic.The important characteristic of the remote sensor is that is not suitable for exposure to the wetted media. The process media can be corrosive, high or low temperature and can contain solids.The key attributes of an isolation diaphragm are high sensitivity and the material. The sensitivity allows a very thin diaphragm to pass through the applied pressure with a minimal change. The raw material is matched to the process media and can be 316L, Hastelloy, Inconel, Monel or any other material that can be formed into a diaphragm.Direct Acting TransducerIn a direct acting assembly the diaphragm displacement with respect to pressure is calibrated. The diaphragm acts like a linear spring and will move a known distance with pressure, and this displacement can be converted into an electrical signal.The diagram shows a simple LVDT sensor design. The purple magnetic core moves with the diaphragm and is detected through the non-magnetic wall of assembly.This direct acting design has several advantages:No Liquid FillThere is no liquid fill as used with isolation diaphragms, and therefore no possibility of contaminating a critical process in the event a diaphragm is damaged.Very Sensitive DiaphragmsA very sensitive diaphragm can be used which can detect down to a few inches of water column. These are suitable for zone pressure measurement, air flow meters and draft pressures used in vapor recovery systems.Interchangeable DiaphragmsThe diaphragm can be interchanged for pressure ranges up to 400 Psi while maintaining the same full scale deflection.Alternative TechnologyThe coil itself is not electronic or microprocessor based - it will remain operational in the event of electrical or electronic interference, and is a suitable backup of other technologies. This is useful in very difficult applications such as nuclear or cryogenic installations. For general applications, signal conditioning is usually included in the transducer and will provide a standard electronic interface.

Complex AssembliesKearflex manufactures complex assemblies that are based upon our capsule sub-assemblies. These are sold to our customers to allow efficient installation in the next level assembly. Advantages to this approach are a turn-key product where the capsule related problems are solved and specialty manufacturing is performed.Customers can use these assemblies on a ship to stock basis with confidence that each unit is calibrated and interchangeable. Inspection and test activities, process fallout and specialty manufacturing efforts are all reduced.Closed loop calibration feedback from our customers allows the performance characteristics of the assembly to be optimized providing the best results in the finished product. Annual and blanket contract arrangements allow for just in time delivery, as well as demand pull formats.Reverse EngineeringThese complex assemblies can be provided on a build to specification basis, but it is usually more practical to reverse engineer the product and adapt the design to known and active Kearflex practices and processes. This is applicable to end of life situations where internal or external vendors have ceased to exist, or abandoned products.It is very common for there to be references to unavailable or inapplicable documents such as proprietary process instructions, obsolete engineering specifications and vendor specific test equipment procedures.The design can be converted to use existing Kearflex processes for welding, brazing, soldering and external processes such as plating, and anodizing. A good portion of the designs can be qualified by similarity, as these adaptations are based upon flight qualified practices that are in active and continuous use with similar products.It is worth noting that the legacy products of this type were all designed around the same time and used similar practices that differed with the particular manufacturer. The conversion to Kearflex practices represents a low design risk and a great deal of similarity to the original products.