SGP/EBBR/E4 - Pressure

Damage to some pressure sensors as a result, apparently, of high battery
voltage, caused pressure readings to vary significantly at a few EBBRs for
several months.  I am being intentionally vague in making that statement as
there are DQRs and at least one PIF that cover those cases, except for the
situation at E4, Plevna, KS.  Some time ago I had the suspect pressure sensors
replaced and "repaired".  Unfortunately, the repairs were insufficient, as
we found out by using Plevna as a guinea pig for the "repaired" sensors to
see if they were working.  It turns out that the three repaired sensors S/N
6500, 6504, and 6509 were better, but still experienced fluctuations in
output that followed battery voltage level as the battery was charged by
the solar panel during the daylight hours.  The fluctuations look like
long-term spikes, positive or negative at different times, and lasted from one
to several hours.  The fluctuations had minimal impact on adjustments to
computed values from the EBBR.

Pressure data from Plevna for the period listed above should not be used
for absolute values.  That is why I marked "questionable", in the data
labelling section, but this applies only to the pressure data itself.

The following documents the use of pressure sensors at Plevna:

1)  The original sensor, S/N 6509 was removed for repair on 1/13/94 and
    replaced with the "repaired" S/N 6500.

2)  S/N 6500 was removed for repair on 2/10/94 and replaced with the
    "repaired" S/N 6504.

3)  S/N 6504 was removed on 3/24/94 and replaced with "repaired" (2nd
    time) S/N 6500.

4)  S/N 6500 was removed on 5/5/94 and replaced with "repaired" (2nd time) S/N
    6504.

5)  S/N 6504 was removed on 5/19/94 and replaced with "repaired" S/N
    6509.

6)  S/N 6509 was removed on 6/30/94 and replaced with a new sensor, S/N
    6579.

Sensors 6500, 6504, and 6509 have been thrown away, as the manufacturer
appears to be incapable of repairing them completely.  Rather than waste
more money in trying to have them repaired, I ordered three new pressure
sensors, of which S/N 6579 is one.  Thus, we now have two new sensors as spares.

• vapor_pressure_top
• atmos_pressure
• vapor_pressure_bottom

• vapor_pressure_bottom
• vapor_pressure_top
• atmos_pressure

• atmos_pressure_mv