Geonics Limited EM38-MK2, Operating Manual

Page 1: ...sissauga Ontario Canada L5T 1C6 URL http www geonics com EM38 MK2 GROUND CONDUCTIVITY METER OPERATING MANUAL GEONICS LIMITED LEADERS IN ELECTROMAGNETICS 8 1745 Meyerside Drive Mississauga Ontario L5T...

Page 2: ...er Switch 10 3 SURVEY PROCEDURES 10 4 ELECTRICAL INTERFERENCE 11 5 NOTES ON SURVEY INTERPRETATION 11 5 1 Linearity of Response 11 5 2 Relative Response with Depth 11 5 3 Multi Layer Calculations 12 5...

Page 3: ...sitions 21 ii Relative Response Curves 22 iii Cumulative Response Curves 24 iv Two Layer Curves 26 v Automatic Calibration Set up 34 vi External Battery Components 35 vii Protective Housing 36 viii Ex...

Page 4: ...t to a digital recorder optional connected to RS 232 port The EM38 MK2 1 provides simultaneous measurements of ground conductivity Quad Phase and magnetic susceptibility In Phase with one transmitter...

Page 5: ...To remove the battery undo two thumb screws holding the cover of the battery compartment at the bottom of the front panel A Mallory MN1604 9 volt Alkaline battery or equivalent gives about 5 hours of...

Page 6: ...otate the Q P zero control until the display reads the value calculated in step 2 In this example it would be 6 mS m Now when you rotate the EM38 to the vertical dipole mode the reading should be 12 m...

Page 7: ...5 Fig A...

Page 8: ...TN 6 the EM38 measures ground conductivity by inducing very small electrical eddy currents in the ground and measuring the magnetic field that these currents generate A small transmitter coil located...

Page 9: ...shall call V Now it can be shown that regardless of any layering in the earth with the instrument at a height of 1 5 meters V should equal twice H conversely if V is not equal to twice H we know that...

Page 10: ...that this site happens to be a region of very high conductivity say 1 000 mS m to take an extreme example If the conductivity is uniform with depth at an instrument height of 1 5 meters it can be sho...

Page 11: ...es an additional signal to be picked up by the receiver coil when the EM38 MK2 is located close to or is lying on the surface of the ground Fortunately this signal decreases rapidly with the instrumen...

Page 12: ...bed in the EM38 MK2 logger manual 2 7 Marker Switch The orange push button switch on the unit front panel can be used during digital data recording to either initiate recording of a data point in manu...

Page 13: ...rent conductivity reading becomes a maximum when a the instrument is directly over the pipe and b also pointing in the same direction as the pipe These remarks apply in the vertical dipole mode which...

Page 14: ...irst the near surface material is the more conductive and vice versa If both readings are essentially the same then the conductivity of the ground is essentially uniform to a depth of about 1 5 meter...

Page 15: ...12 By translating this data as described above on top of the various curves of Fig 4 we see that good agreement is achieved for t 0 3 m and k 2 1 2 Furthermore we note that in the vertical dipole mod...

Page 16: ...etermine z the thickness of the conductive upper layer Given z use Fig 3 to obtain either Rh z or Rv z whence 1 ah 1 Rh z av 1 Rv z Note that in the event that neither 1 2 or 2 1 it is still possible...

Page 17: ...MK2 also reads in units of mS m where 28 5 ppt 7 12 for 0 5 m of the secondary field relative to the primary field corresponds to 1 000 mS m The following relation can be used to convert mS m to ppm 1...

Page 18: ...more detailed description on the use of two communication method is provided in the EM38 MK2 Logger Manual 10 OPTIONAL COMPONENTS 10 1 External Battery A provision is provided on the instrument front...

Page 19: ...ies will lose 2 to 3 of their charge per month when stored at 20 C Deep Discharge Protection The Dryfit battery unlike conventional lead storage batteries is protected against excessive discharge In t...

Page 20: ...on the housing cover are to allow for connection to the external battery and to the recording device 10 3 Extender Arm A collapsible extender arm see Figure 11 can be used to conveniently carry the i...

Page 21: ...recision 0 1 of full scale Primary Field Source Self contained dipole transmitter Sensor Two self contained dipole receivers Intercoil Spacing 1 and 0 5 metres for EM38 MK2 1 metre for EM38 MK2 1 Oper...

Page 22: ...al Dipole Positions ii Relative Response Curves iii Cumulative Response Curves iv Two Layer Curves v Automatic Calibration Set up vi External Battery Pack and Charger vii Protective Housing viii Exten...

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Page 40: ...be used to connect EM38 MK2 to other computer or data acquisition system provided that such computer or system has an RS 232 port EM38 MK2 INTERFACE CABLE pin assignment is summarised as follows 3 pi...

Page 41: ...annel 3 Low Byte Byte 9 Channel 4 High Byte Byte 10 Channel 4 Low Byte Byte 11 Channel 5 High Byte Byte 12 Channel 5 Low Byte Byte 13 Channel 6 High Byte Byte 14 Channel 6 Low Byte Byte 15 FF High End...

Page 42: ...ivity FOR 1M Channel 4 In phase FOR 1M Channel 5 Temperature FOR 1M Channel 6 Temperature FOR 0 5M DATA INFORMATION for Channel 1 4 160mV 0000HEX OV 8000HEX 160mV FFFFHEX 1mV 8mS m 1mS m 25 6 raw data...

Page 43: ...n the test coil on The instrument should read approximately 90 mS m for 1 m coil separation and 185 mS m for 0 5 m separation If the reading deviates more than 4 mS m and 8 mS m for 1 m and 0 5 m sepa...

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