SBP

Self-boring pressuremeter

Using a spreadsheet to derive calibration factors

Note: templates for the techniques discussed in this recipe are attached above. Both Microsoft Excel Macro Enabled Worksheet and LibreOffice Open Document Spreadsheet formats are available. These templates can be used to record a full calibration history for our instruments.

Replacing a 'Porosint' disc

Note: Figures and PDF version still required.

The Pore Pressure Cell Caps are fitted with sintered phosphor bronze filters. In time these 'Porosint' filters need replacing:-

  1. Support the front face of the Pore Pressure Cell Cap and press out the existing filter disc from the back face. A piece of brass rod or similar, less then 10 mm in diameter, can be used as a drift either in a press or tapped lightly with a hammer.

Knowing the cutter postion

Note: Figures and PDF version still required.

Refer to Figure 10-1 for a view of a cutter in its shoe.

There is a range of possible movement of the cutter in the shoe:

  1. The fully forward position is set by the two M5 bolts which stop the cutter falling through the bottom bearing.

  2. The fully back position is set by the spacers which sit between the cutter and the bottom bearing.

Drying out desiccators

The electronics units are sealed boxes fitted with desiccators. These absorb the small amount of moisture that, despite the sealing, eventually penetrates the units.

If the windows of the desiccators show pink then they must be changed. Spares are supplied, so fit the spare and dry the old desiccator.

Demobilising the equipment - SBP

Demobilisation with hydraulic power pack

  1. Thoroughly clean the instrument, removing all surface dirt.

  2. Strip off the lower end with the cutter assembly and dismantle (see Fitting the cutter). Clean each part.

  3. Remove the top bearing adaptor and clean out all dirt, checking that the pair of bearings are free.

Mobilising the equipment - SBP

Mobilisation with hydraulic power pack

  1. Calibrate the pressuremeter for

    1. Arm sensitivity – see Calibrating an arm - SBP.

    2. Pressure Cell sensitivity – see Calibrating the pressure cells - SBP.

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