«Advanced model Introduction The PosiTector UTG is a hand-held Ultrasonic Thickness Gage that uses the non-destructive ultrasonic pulse-echo principle ...»
Ultrasonic Thickness Gage
Quick Guide v. 3.0
The PosiTector UTG is a hand-held Ultrasonic Thickness Gage
that uses the non-destructive ultrasonic pulse-echo principle to
measure the wall thickness of a wide variety of materials. It
consists of a body (Standard or Advanced) and probe (UTGC or
UTGM, see pg. 2).
This Quick Guide summarizes the basic functions of the instrument. Download the full instruction manual at:
www.defelsko.com/manuals Quick Start The PosiTector UTG powers-up when the center navigation button is pressed. To preserve battery life, the instrument powers down after approximately 5 minutes of no activity. All settings are retained.
1. Remove the protective rubber cap from the probe.
2. Power-up Gage by pressing the center navigation button.
3. Zero the probe (see pg. 6)
4. Select the correct velocity of sound (see pg. 7)
5. Measure the part (see pg. 3) The Coupled Symbol appears when the Typical Display probe is ultrasonically connected with a surface.
Currently Measurement Steel selected Mode currently set material to multiple-echo (UTGM probe only) Battery inch Icon Current Unit of Measurement Measurement Probes To disconnect a probe from a body, power-down the instrument and slide the plastic probe connector horizontally (in the direction of the arrow) away from the body. Reverse these steps to attach a new probe.
When powered-up the PosiTector automatically determines what type of probe is attached and does a self-check.
PosiTector UTG probes transmit an ultrasonic pulse into the material to be measured. This pulse travels through the material towards the other side. When it encounters an interface such as air (back wall) or another material, the pulse is reflected back to the probe. The time required for the pulse to propogate through the material is measured by the Gage, represented as t1 and t2 below.
PosiTector UTGC and UTGM (in single-echo mode) probes determine thickness by measuring t1 (uncoated) or t2 (coated), dividing it by two and then multiplying by the velocity of sound for that material (steel). See Figure 1.
t2 Probe t1 Probe coating steel steel
For uncoated materials t1 relates directly to material thickness.
When a material is coated the propagation time is increased and is shown above as t2.
Coatings such as paint have a slower velocity of sound than that of metal. Thus the single-echo technique will produce a thickness result greater than the actual combined coating+metal thickness.
The PosiTector UTGM in multiple-echo mode determines thickness by measuring the time between at least three consecutive back wall echoes.
t1 t2 t3 t1
In the figure above, multiple-echo mode measures only the time between echoes. Regardless of whether the steel is coated or not, all times between echoes are the same. In multiple-echo mode the Gage determines thickness by measuring t1+t2+t3, dividing it by six and then multiplying by the velocity of sound for that material. The resultant thickness calculation made by the instrument is therefore an accurate measurement of the steel thickness only, disregarding the coating thickness.
The velocity of sound is expressed in inches per microsecond or meters per second. It is different for all materials. For example, sound travels through steel faster (~0.233 in/µs) than it travels through plastic (~0.086 in/µs).
How to Measure
1. Remove rubber cap from probe. Couplant (glycol gel - included) must be applied to the surface to be tested to eliminate air gaps between the wear face and the surface. A single drop of couplant is sufficient when taking a spot measurement.
2. Place the probe flat on the surface. Use moderate pressure to press against the top of the probe with the thumb or index finger.
When the probe senses echoed ultrasound, a coupled symbol will appear on the display and thickness values will be displayed. While the probe is coupled, the PosiTector UTG continually updates the display.
3. When the probe is removed from the surface, the last measurement will remain on the display.
Occasionally, excess couplant will remain on the probe when the probe is lifted from the surface. This may cause the PosiTector UTG to display a final measurement value different from those observed when the probe was on the surface. Discard this value and repeat the measurement.
Surface Conditions Ultrasonic measurements are affected by the condition, roughness and contour of the surface to be tested.
Measurement results may vary on coarse surfaces. Where possible, it is recommended to seat the transducer on a smooth flat surface that is parallel to the opposite side of the material.
On rough surfaces, the use of a generous amount of couplant minimizes the surface effects and serves to protect the transducer from wear, particularly when dragging the probe across a surface.
UTGM Probes: On smooth, uncoated metal surfaces the Gage (in multiple-echo mode) may occasionally be unable to give a measurement result even when the "coupled" symbol appears.
Use additional couplant and lighter pressure on the probe when measuring. Alternatively, laying a plastic shim on the surface with couplant applied to both sides to simulate a painted surface will help produce a steel-only thickness measurement (multiple-echo mode). Switching the Gage to single-echo SE mode (see pg. 9) will also help produce a steel-only thickness measurement.
Calibration, Verification and Adjustment Three steps ensure best accuracy…
1.Calibration - typically done by the manufacturer or a qualified lab. All probes include a Certificate of Calibration
2.Verification of Accuracy - as done by the user on known reference standards such as calibration step blocks.
3.Adjustment - to a known thickness or sound velocity for the material to be measured Calibration Calibration is the controlled and documented process of measuring traceable calibration standards and verifying that the results are within the stated accuracy of the Gage. Calibrations are typically performed by the Gage manufacturer or by a certified calibration laboratory in a controlled environment using a documented process.
Verification Gage accuracy can and should be verified using known reference standards of the material to be tested.
Verification is an accuracy check performed by the user using known reference standards. A successful verification requires the Gage to read within the combined accuracy of the Gage and the reference standards.
Adjustment Adjustment, or Calibration Adjustment is the act of aligning the Gage's thickness readings to match that of a known reference sample. See Calibration Adjustment pg. 6.
Cal Settings Menu Zero PosiTector UTG probes can be "zeroed" to compensate for temperature and wear. This action is not required when operating in multiple-echo mode (UTG M probes only) except when the instrument is new and after a Reset (pg. 8). However it ensures best accuracy when operating in SE (single-echo) mode. Therefore it is a good idea to "zero" the probe before each work shift and when the temperature of the part changes. During zeroing, it does not matter what the current velocity setting is.
1. Make sure the instrument is on and the probe is wiped clean.
2. Apply a single drop of couplant onto the zero plate located on the underside of the probe connector. DO NOT apply couplant directly onto the probe face.
3. Select the Zero menu option and follow the on-screen prompts.
Calibration Adjustment The PosiTector UTG is factory calibrated. But in order for it to take accurate thickness measurements of a particular material it must be set to the correct sound velocity for that material. Be aware that material composition (and thus its sound velocity) can vary from stated tables and even between lots from a manufacturer.
Adjustment to a sample of known thickness of the material to be measured ensures that the Gage is adjusted as close as possible to the sound velocity of that specific material. Samples should be flat, smooth and as thick as the maximum expected thickness of the piece to be tested.
The PosiTector UTG allows four simple adjustment choices. All four methods are based on the simple premise of adjusting the sound velocity. The first three adjustment methods make 1-point calibration adjustments to optimize the linearity of the PosiTector UTG over small ranges. The fourth method makes a 2-point calibration adjustment to allow for greater accuracy over a large range.
Thickness The most common method of adjustment is to measure a sample of known thickness. Select a reference standard of material as close as possible in composition to the intended application. For best results, the thickness of the reference standard should be equal to or slightly greater than the thickness of the part to be measured.
Material If a known thickness of the material is not available, but the material is known, this quick adjustment allows the user to load one of several preprogrammed material velocities.
Velocity If the sound velocity for the test material is known, the Gage can be adjusted to that specific sound velocity.
2 Pt Adjust A 2-Point adjustment allows for greater accuracy while simultaneously adjusting probe zero. Select two reference standards as close as possible in composition to the intended application. For best results, the thickness of the thicker reference standard should be equal to, or slightly greater than the thickest part to be measured. The thickness of the thinner reference standard should be as close as possible to the lower end of the expected measurement range.
Cal Lock When checked, the icon appears and the current Cal settings are “locked” to prevent further user adjustments. Uncheck to make further adjustments.
Perform a more thorough Hard Reset by powering down the instrument, waiting several seconds, then simultaneously holding both the center and (+) buttons until the Reset symbol appears. This returns the instrument to a known, “out-of-the-box” condition. It performs the same function as a menu Reset with the
- Bluetooth Pairing info is cleared.
- Menu settings are returned to the following:
Units = millimeter Battery Type = Alkaline Flip Display = Normal Backlight = Normal Auto Sync = OFF Bluetooth Streaming = OFF White on Black = OFF USB Drive= ON Language = English NOTE:
- Date and Time are not affected by either Reset.
Scan Normally, the PosiTector UTG takes a single spot measurement at a rate of 6 readings per second while in contact with a surface.
When the probe is lifted, the last reading will remain on the display.
It is sometimes necessary to examine a larger region to locate the thinnest point. When Scan is selected, the PosiTector UTG will measure at a rate of 20 readings per second and display min/max values.
A Scan (Advanced models only) A display in which the received pulse amplitude is represented along y axis and the travel distance of the ultrasonic pulse is represented along the x axis.
Switches from multiple-echo to single-echo mode:
- To detect pits and flaws
- To increase the measurement range
- To obtain thickness measurements in circumstances where multiple-echo can not Battery Type Selects the type of batteries used in the instrument from a choice of “Alkaline”, “Lithium” or “NiMH” (Nickel-metal hydride rechargeable). If NiMH is selected, the instrument will trickle charge the batteries while connected via USB to a PC or optional AC charger (gage must be powered ON). The battery state indicator icon is calibrated for the selected battery type. No damage will occur if the wrong battery type is selected. DeFelsko recommends eneloop (NiMH) rechargeable batteries.
Standard models store up to 250 readings in one batch.
Advanced models store 100,000 readings in up to 1,000 batches. “New Batch” closes any currently opened batch and creates a new batch name using the lowest available number. The icon appears. New batch names are date stamped when they are created.
NOTE: This Quick Guide summarizes the basic functions of the
instrument. Download the full instruction manual at:
www.defelsko.com/manuals Screen Capture Press both (-)(+) buttons at any time to capture and save an image copy of the current display. The last 10 screen captures are stored in memory and can be accessed when connected to a computer (see USB mass storage pg. 11).
Outputting Stored Readings USB mass storage - connect your PosiTector to a PC/Mac using the supplied USB cable to access and print stored readings and graphs. No software or internet connection required.
PosiTector.net - a free web-based application offering secure centralized storage of thickness readings. Access your readings from any web connected device. www.PosiTector.net Connect Menu Sync Now Immediately initiates synchronization with PosiTector.net when connected (USB or Bluetooth) to an internet connected PC running PosiTector Desktop Manager.
Auto SYNC Allows the instrument to automatically synchronize with PosiTector.net when initially connected to an internet connected PC running PosiTector Desktop Manager.
Additional measurements added to memory while connected are synchronized only when the USB cable is disconnected, then reconnected or when ConnectSync Now is selected.
USB Drive The instrument uses a USB mass storage device class which provides a simple interface to retrieve data in a manner similar to USB flash drives, cameras or digital audio players.
NOTE: When connected, power is supplied through the USB cable. The batteries are not used and the body will not automatically power down. If rechargeable (NiMH) batteries are installed, the instrument will trickle charge the batteries.
Bluetooth (Advanced models only) Allows individual readings to be sent to a computer or compatible device as they are taken using Bluetooth wireless technology.
See www.defelsko.com/bluetooth Updates Determines if a software update is available for your instrument.