How to Recalibrate the Bloodhound Vacuum Sensor - Method 1

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How to Recalibrate the Bloodhound Vacuum Sensor - Method 1


The Bloodhound's vacuum sensor is a useful instrument for real-time analysis of
problems in the unit, blockages, filter conditions, and rig-up.  While it is a solid
performer most of the time, certain events such as excessive time on high-vacuum
and/or significant barometric pressure events can cause it to become slightly mis-
calibrated.  This is normally not a large problem as the primary function of the
sensor is to identify a blocked sample line; however, if you use the sensor as a
general "health metric" and/or "line-troubleshooting metric" on the Bloodhound this
can be annoying to say the least.  There are three methods for re-calibrating the
vacuum sensor.  This method is the simplest.

HOW TO:
1)  This is recommended when the drill bit is off bottom.  Make sure that the bit
     is off bottom or tripping altogether.

2)  Observe what the vacuum reading is before disconnecting in the sample line.

3)  Disconnect the sample line from the Bloodhound and make sure that there is
     nothing connected to the outside of the Bloodhound's sample inlet (no fuel filter,
     hose segment etc. - Observe the following image for an example).  Only the
     brass barb should be left (this is important as the vacuum on the machine is
     based on the length between that brass barb's inlet, the sample pump, and the
     "T" to the vacuum sensor.  Any variation in this will cause it to calibrate with
     an incorrect baseline).
    

4)  Let the Bloodhound it sit and run on "open air" for no less than two (2) minutes
     in order to make sure the vacuum reading settles out properly.

5)  Observe the vacuum reading on the Bloodhound.  Under normal conditions, the
     the vacuum with no sample line connected should be between -6 and -10 (with
     potentialy slight variances outside of this range).  If it is excessively outside of
     this range on open air, you should attempt to re-calibrate the Bloodhound's
     vacuum sensor.  To do this, proceed to the next step.

6)  After the 2 or more minutes has elapsed, reboot the Bloodhound (with the sample
     line still disconnected).  To reboot the Bloodhound:
     a)  Pull the power cord from the Bloodhound 's power port as illustrated below:
          
     b)  Press the "Start/Stop" button as illustrated below.
          
     c)  Re-connect the power cord that you disconnected above and the Bloodhound
          will re-start.

7)  Let the rebooting process complete.  The process of rebooting with the sample line
     disconnected will automatically recalibrate the Bloodhound's vacuum sensor.

8)  Observe what the vacuum is after the reboot and re-calibration.  If it was too high
     or too low before, the issue should be resolved now.  If it is not, proceed to the
     next step.

9)  Check the inner-plumbing of the sample line:
     a)  Open the case of the Bloodhound by removing the four (4) Philips' head screws
          as illustrated below:
          

     b)  Lift the face of the Bloodhound out and tip it toward the front of the Bloodhound
          (toward the handle).
     c)  Observe the inlet's inner connections, and in particular the inner filter (as shown
          in the following photograph which depicts a filter after 1 year of use.):
         
     d)  If there are any obvious obstructions in the clear tubing remove them, and you
          can try disconnecting/reconnecting them in order to clear any unseen debris.
     e)  If the filter is clearly dirty, it can be replaced with a common G4164 plastic
          filter, available at most auto parts stores.

10)  After repairs to the inside of the Bloodhound's plumbing, you must again re-calibrate
       the vacuum sensor.  In order to do this, repeat steps 1 through 7 above.

12)  If you are still not able to stabilize the vacuum on open air to an acceptable range,
       the sensor must be repaired at the iBall Instruments shop.  You may choose to run
       a lighter test and/or a trap test, and/or a Chromatograph Lighter Test to determine
       if the Bloodhound is functioning well enough to complete the current logging job.


OTHER ARTICLES OF INTEREST:

How to Perform a Basic Lighter Test on the Bloodhound: 
http://www.bhkb.org/kb2/KnowledgebaseArticle50019.aspx

How to Perform a Chromatograph Lighter Test on the Bloodhound:
http://www.bhkb.org/kb2/KnowledgebaseArticle50030.aspx



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Details
Last Modified:8/5/2014 8:38:54 AM

Last Modified By: syonker

Type: FIX

Level: Novice

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