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P-Wave Quick Start Guide
Table of Contents
Introduction
Running a sample
Supplementary Information
Evaluating Your Measurement
A) First Arrival Picking
B) Manual pick
C) Running a Standard as a QAQC Check
Viewing Your Data
Calibrating the PWV CALIPER
Credits
Archived Versions


The P-wave velocity station.

Introduction
The P-wave velocity gantry measures the speed at which ultrasonic sound waves pass through materials that are placed between its transducers; this includes section halfs, discrete samples, and mini-cores.
The three orthogonal sets of piezoelectric transducers allow the velocity to be determined in the X-, Y-, and Z-directions (Figure 1) on working-half split-core sections. The P-wave bayonets (PWBs) measure the velocity along the core (Z-direction) and across the split-core face (Y-direction), and a P-wave caliper (PWC) measures the velocity perpendicular to the split-core face (X-direction). 
For discrete sample cubes, the velocity is measured along each of the three axes separately using the PWC; whereas, mini-cores are measured along the axis of the cylinder (X-direction). For discrete samples cubes and mini-cores, all sample information, including offset, is entered by the user.
Figure 1. Core section-half liner showing top of section and relative orientations.
Procedures
Preparing the Instrument
CAUTION: DO NOT place anything, including samples, below the instruments before opening the program. The program will close all transducers upon startup, and CAN CAUSE SEVERE INJURY.


Copy From SHMSL
Preparing Samples:

  1. Make sure the sensors are clean.
  2. For section halfs, place the desired measurement location underneath the desired sensor. Make sure that the section is oriented with the blue end-cap towards the laser (Figure ).
  3. Place a small piece of Glad Wrap at the measurement location to keep the sensors clean and the core free of contamination (including water).
  4. Place one or two drops of deionized (DI) water at any relevant sample/sensor interface. It will improve the signal transmission.
  5. For discrete samples, place them within the caliper transducers with the desired axis oriented vertically.


Making a Measurement:

  1. Select the measurement type. Nine different measurement configurations are available (Figure ).
  2. Depending on measurement, insert the bayonets or close the caliper onto the sample. Click the instrument motion buttons to slowly lower the transducers to the sample (Figure ). The autoclose button functions for either the caliper or the bayonets.


Note: For the bayonets, insert them until the entire sensor (the circular part of the black sensor dot) is within the sample. Stop before the bayonets make contact with the liner.

  1. The program continually updates the velocity calculation and displays the value (averahe of the set of stacks) in the Velocity-Auto box (Figire ). It also displays a signal graph with a red vertical auto-pick location line (Figure 7), where the program's algorithm has placed the first arrival wave.


Note: Typical slide bar settings are 100 for the stack bar and10mV for the threshold bar.

  1. Click Save Data


Note: If the velocity is out of the expected range, or the pick location is not near or at the first arrival wave, contact the PP technician.

  1. Save Your Data
  2. The Section Information screen is displayed.
  3. Place the cursor in the SCAN field and scan the section label. SAMPLE ID and LIMS ID automatically fills. These ID tags contain information on expedition, site, hole, core, section number and length.


Additional entry field options are the LIMS and MANUAL tags.

  1. Check that the test offset data is correct for section halves. If you are measuring a discrete sample, the offset is already in the database.


  1. Click Save Data



Figure 3. Program home screen.

Figure 4. Section-Half loaded under caliper.

Figure 5. Measurement Configuration Options

Figure 6. Instrument motion buttons.

Figure 7. Clean waveform indicating a strong/good signal.



Figure 9. Sample Information window with relevant sample ID fields populated.
Credits
This document originated from Word document Gantry Velocity: Quick Start Guide Version 1.0; Version 372 written by A. de Loach (2017-12-16). Credits for subsequent changes to this document are given in the page history.
Archived Versions
P-Wave Quick Start Guide (*.pdf)
PWV_QSG_372.docx: A Word document of the Gantry Velocity: Quick Start Guide

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