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Summary of Contents for PASI GFA-50
- Page 1 BOREHOLE GEOPHONE Mod. GFA-50/100 User Manual Edition 2025 Copyright 2025 P.A.S.I. All Right Reserved P.A.S.I. srl - via Galliari 5/E - 10125 TORINO - ITALY Tel.+39 011 650.70.33 Fax +39 011 658.646 E-MAIL sales@pasisrl.it www.pasisrl.it www.pasigeophysics.com 29/04/25...
- Page 2 PLEASE NOTE When the geophone is clamped to the side of the hole it is important to reach minimum pressure of 2 bar (lower pressure does not guarantee that the pneumatic circuit will hold). When unclamping move the lever (UNCLAMP/CLAMP) to the UNCLAMPED position very slowly to allow time for the air to be released and pressure to be lost.
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Page 3: Standard Package
• Cable adapter from borehole geophone panel to seismograph connector (standard NK2721C – other option on request) • User Manual (in PDF format – see PASI USB pen drive) Cleat Assembly (to suspend the GFA at the mouth of the borehole) - Page 4 OPERATING INSTRUCTIONS: A good coupling with the borehole wall is necessary not only for a good transmission of the seismic waves, but also to avoid any damage of the cable. The first thing to do is positioning the 3D Borehole geophone at the proper depth inside the borehole.
- Page 5 Now you can proceed by connecting the pump air tube and the seismograph adapter cable to the related plugs on the reel panel (see FIG.3). For clamping operation, move the hand lever to the right. Connect the air tube of the pump to the AIR PUMP input and start inflating;...
- Page 6 At the end of the measuring session you can unclamp the borehole geophone for the last time and upload it at the surface. Now disconnect the seismograph adapter cable; to disconnect the air tube, don’t forget the very last operation: To remove the air tube, press the grey ring of the input air pump plug and –...
- Page 7 3. Align the geophones, insert the cable of the second geophone in the appropriate slot (see image below) and fix the extension shaft (Spacing Assembly) using the three screws supplied (see image below) . WARNING: the position of these screws is unique and you must respect it. To facilitate the assembly, place the two geophones on a flat surface with the flaps open so that to ensure alignment.
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Page 8: Cable Connections
CABLE CONNECTIONS: GFA borehole geophone is delivered with a cable adapter with 27 poles Cannon connector as follows: Vertical channel (Z) ➔ pin 1(+) (BROWN) & 2(-) WHITE of the connector Horizontal channel (X or H1) ➔pin 3(+) GREEN & 4(-) YELLOW of the connector Horizontal channel (Y or H2) ➔... - Page 9 The GFA can be adapted in different borehole sizes. If the diameter is too small or too big, it is possible to remove the spacer block or to substitute it. Custom-made spacers are manufactured by PASI s.r.l. on request. FIG 4: GFA probe - with standard spacer block - in clamped position.
- Page 10 The GFA down-hole 3D geophone is lightweight and easy to carry (only 12 kg for the GFA-50 and 17kg for GFA-100). The outside case of the probe is in anodized aluminium, with a steady structure for long time using and easy maintenance.
- Page 11 CONNECTING THE GFA TO A PASI SEISMOGRAPH (physical connections) - 12 channel instruments: Channel 1 (-) 1 (+) 2 (-) 2 (+) 3 (-) 3 (+) - 24 channel instruments: Channel Connector 1-12 Channel 12 (-) 12 (+) 11 (-)
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Page 12: Main Technical Specifications
MAIN TECHNICAL SPECIFICATIONS: 1.Natural frequency: 10±5% Hz 2.Sensitivity: 1000±5% ( 3.Damping factor: 0.55±10% 4.Inner resistivity: 3500±5% (core body) ≤0.2% 5.Distortion: ≥50M 6.Insulation resistance: 7.Running temperature: -40°C to+70°C Φ50*570mm 8.Probe size: 20° 9.Normal working angle: 10.Cable length: 50/100m P.A.S.I. srl - via Galliari 5/E - 10125 TORINO - ITALY Tel.+39 011 650.70.33 Fax +39 011 658.646 E-MAIL sales@pasisrl.it...
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