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High Pressure Applications

By Jerry Philips on May 4, 2018 in Fiberoptic Sensors, High pressure environments, Non-Contact Sensing

There are three options for sealing the leak path thru the fibers under pressure:

1. Epoxy filled tips

2. Sapphire Windows epoxied into tip counterbores

3. Sapphire Windows brazed into tip counterbores

The best solution for an application depends upon several factors such as: the size of the fiber bundle, the dimensions of the probe tip, as well as the amount of applied pressure. Pressure can be static, reciprocating or pulsing. Extreme temperatures can be coupled with high pressures, and the probes could be submerged in oils or cryogenic fluids. Effectiveness of the seal and cost are major considerations. Philtec engineers can assist with the choice and design of the probe.

Design Guidance

Pressurized Cryogenic Fluids

Example: High Pressure Application

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ROCKET ENGINES for SPACE LAUNCH VEHICLES

By Jerry Philips on April 3, 2018 in Cryogenic environments, cryogenic turbopumps, Fiberoptic Sensors, High pressure environments, Measurements in fluids, Non-Contact Sensing, Rotor Dynamics, Space Launch Vehicles

A new generation of LOX/Methane engines are under development, and many have used Philtec’s FODS (Fiber Optic Displacement Sensors) for rotor dynamics measurements in the testing phase. Fiber optic probes are an ideal sensor choice in these applications where they are exposed to pressurized cryogenic fluids.

In 2016-2017, 100 sensors are delivered to companies testing advanced turbopump designs.

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Curved Glass Shape Turnkey Solution

By Jerry Philips on February 23, 2018 in Auto Glass Shape Gaging, Fiberoptic Sensors, Non-Contact Sensing, Quality Control, turnkey solution

Philtec has partnered with the Italian company Technosens to provide the complete turnkey solution for automatic production lines. The method used is to compare a production piece glass shape to the shape of a master frame as shown here.

The production line glass is placed against the master frame, and Philtec’s non-contact sensors measure distance to the glass at 50 locations. With data from 50 sensors, the shape of the glass is accurately mapped. Philtec’s non-contact optical sensors provide a scratch-free solution that is ideal for thin glass, where contact gages such as LVDTs can move and distort the glass when applied via air pressure.

With Technosens equipment, each measured piece has a complete traceability and the production is real time monitored with advanced statistics on process, moulds, system analysis (SPC, MSA) to have the maximum reduction of discarded pieces.

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Sensor Probe Installations with Tilt

By Jerry Philips on February 15, 2018 in Fiberoptic Sensors, Non-Contact Sensing, Probe Misalignment, Target Tilt

Sensor probes are to be generally mounted normal (perpendicular) to a target surface. With some applications, such as displacement of a cantilever beam, the target surface rotates as deflects. In other applications, due to installation constraints, the probe can not be mounted normal to the surface. In applications where tilt is unavoidable, what sensors can be used?

Our latest application note Sensor Applications With Tilt provides guidance on sensor performance and selection.

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Fiber Optic Displacement Probes in Liquid Oxygen

By Jerry Philips on February 9, 2018 in Cryogenic environments, cryogenic turbopumps, Fiberoptic Sensors, Liquid Oxygen, Methane, Non-Contact Sensing, Submerged in fluids

When the cryogenic medium is Liquid Oxygen (or Liquid Natural Gas), calibration in water is a better approximation than calibration in air:
Air Refractive Index = 1.000
Liquid Oxygen Refractive index = 1.221
LNG Refractive Index = 1.286
Water Refractive Index = 1.332

A sensor’s operating range is extended in proportion to the ratio of the refractive indices.

For example, to calculate a sensor’s response in LOX, first calibrate the sensor submerged in water. Then remap the displacement data by the ratio 1.221/1.332.

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Cryogenic Turbopumps

By Jerry Philips on March 17, 2017 in Cryogenic environments, cryogenic turbopumps, Fiberoptic Sensors, High pressure environments, Liquid Hydrogen, Liquid Nitrogen, Liquid Oxygen, Measurements in fluids, Methane, Space Launch Vehicles, Submerged in fluids

Space launch vehicles use liquid propellant rocket engines with high-pressured turbopumps to deliver extremely low temperature propellants of liquid hydrogen, liquid nitrogen, liquid oxygen or liquid natural gas (methane) to a combustion chamber in the engine. During developmental testing of advanced turbopump designs, engineers monitor the radial and axial displacements of the rotors over the entire speed range of operation.

Philtec’s FODS (Fiber Optic Displacement Sensors) are being successfully used for rotor dynamics measurements in cryogenic fluids. When a fiber optic probe is submersed in a fluid, light rays diverging from the probe tip are more collimated than they would be in air. This increases the operating range of the sensor. The degree of collimation is proportional to the index of refraction of the fluid.

Refractive Index of Common Cryogenic Fluids

1.0002926 Air

1.0974 Liquid Hydrogen

1.2053 Liquid Nitrogen

1.221 Liquid Oxygen

1.286 Liquid Natural Gas (Methane)

OPERATION IN CRYOGENIC FLUID, EXAMPLE

Philtec provides the rocket engineers with a calculated best estimate of sensor performance following this example:

calibrate the displacement sensor in air (or water), then
rescale the gap data to derive an estimate of the sensor output in the cryo fluid.

For example, a sensor is calibrated to a target surface in Air with Refractive index of 1.0002926

For a probe immersed in Liquid Hydrogen with Refractive index of 1.0974, the sensor’s calibration gap data is scaled by the ratio of the Refractive Indices:

1.0974 ÷ 1.0002926 = 1.0971

Two calibration charts are provided: One for operation in Air; one for operation in LH2

Example Chart_LH2

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Glass Shape Gaging

By Jerry Philips on March 15, 2017 in Auto Glass Shape Gaging, Fiberoptic Sensors, multiplexing sensors, Non-Contact Sensing, Quality Control

The shape of curved glass windows in automated production lines is typically measured using LVDT contact sensors. When the glass is very thin and light, normal pressure of the LVDT probes tend to move the glass from the holding fixture and corrupt the measurement. Philtec’s non-contact FODS (Fiber Optic Displacement Sensors) solve the problem.

This month Philtec has delivered 100 sensors for a gaging station at a European automotive glass window manufacturing plant (50 for the driver side, and 50 for the passenger side). These sensors are very accurate, and prevent movement or scratches on the glass.

The model RC171 FODS is a reflectance compensated optical sensor with 15 mm operating range. It is insensitive to part-to-part reflectance variations as well as to ambient lighting interference. Data from a set of 50 probes is read in less than 1 second.

http://www.philtec.com/downloadssupport/documentlibrary/documents/applicationnotes/V9N1_ContouredGlassInspection.pdf

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Wireless Sensors for Turbine Blade Tip-to-Casing Cold Clearance Measurements

By Jerry Philips on September 24, 2015 in Fiberoptic Sensors, Non-Contact Sensing, Quality Control, turbine blade tip clearance, Wireless Sensors

Gas and steam turbine manufacturers of fossil power plants have long used hand-held feeler gages to measure turbine blade tip clearances and inspect the roundness of the TBC linings at access ports provided for that purpose. With new construction and at overhaul, turbine blade tip-to-casing clearances at room temperature must be properly set.

Philtec has developed the wireless non-contact sensor system CMS3400 to replace manual feeler gage methods. As a technician slowly jogs a rotor thru 360° of rotation, Gap and Angle data pairs are simultaneously recorded from 4 rows of blades and saved to a USB flash drive for offloading and data analysis. CMS3400 is a four channel wireless sensor system that digitally captures the full 360° picture of blade tip-to-casing roundness and clearance data. This product represents a major advancement in the state-of-the-art.

MORE INFO AT Wireless Sensors for Blade Tip Clearance

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USB Powered Sensors

By Jerry Philips on March 15, 2015 in Fiberoptic Sensors, Miniaturized Sensors, multiplexing sensors, Non-Contact Sensing, USB Powered Sensors

Introducing our smallest and most powerful digital sensor series with USB output: the MicroDMS series (µDMS). Powered via any standard USB port, or multiplexed via any standard USB hub, this new sensor series boasts a maximum data sample rate of 16,000 samples per second in a 145 gram enclosure of LWH dimensions 75 x 50 x 23 mm. With Philtec’s fully-featured DMS Control freeware, this sensor is a powerful solution to many measurement problems.

With its miniaturized size and USB power, it is an ideal solution for high density workstations where space is at a premium. Sensors can be stacked together to form the most compact arrangement. For example, 6 sensor modules can be stacked together in a space of 132 mm.

Contact our application engineering staff to explore the possibilities the µDMS series offers for you.