11
CSLD Troubleshooting
Actual CSLD Test Problems Analyzed
11-16
ANALYSIS OF RATE TABLE (IA51)
LRT
Looking in the leak rate column (LRT) the test results start off looking reasonable, if anything they tend to be
positive. Leak rates suddenly change on the 8th and are consistently negative. There is another transition on the
13th where the leak rates return to the pattern observed prior to the 8th - slightly positive.
ST
the status table indicates that the tests between the 8th and 13th are the only ones contributing to the overall leak
rate. This is indicated by a status code of 0. The reason CSLD is favoring these tests will be explained below.
DATE
The DATE field indicated that tests are being performed on a regular basis, several tests a day.
CSLD will complete a test after 3 hours and start a new test if the tank remains idle. The tests between the 8th
and the 13th are being performed continuously, one test every 3 hours. This is inconsistent with the tests outside
this date range.
INTVL
This is the length of a test in minutes. With the exception of the period between the 8th and 13th, test lengths are
much less than 140 minutes. this indicates the site is a 24-hour site because tests are halted by dispensing, not
the 3-hour CSLD limit. Test intervals are less than 3 hours because CSLD eliminates the first part of a test. The
amount of time eliminated varies with the feedback variables.
Together, the interval and date information indicates that the tank was IDLE during the 8th and 13th period.
In reference to all the test in the rate table, these tests also have the longest interval time, one of the reasons
CSLD is favoring these tests. All the tests with status code 1 were rejected due to short intervals.
DSPNS
The dispense factor is an indication of the amount of dispensing that occurred during the last 24 hours. It is not as
simple as the amount of gallons dispensed during the last 24 hours because the hourly volumes are weighted in
such a way that the most recent dispensing value contributes more to the dispense factor than dispensing volume
that has occurred 23 hours ago. But it can be used as a relative indication of tank activity. The dispense factor for
the above data set shows a typical value of 600. But the dispense factor during the 8th and 13th period drops
rapidly to single digit values. This is another indication that there was no dispensing during this period.
CSLD prefers tests with low dispense factors, another reason why CSLD is favoring these tests. All the tests
rejected with error code 3 were rejected because of high dispense factors.
VOL
The volume parameter indicates the volume at the start of the test. The volume during the trouble period started at
6027 and slowly dropped to 6009 gallons. Note that none of the volumes exceeded 6027.
EVAP
If the Reid Vapor Pressure table has been entered, the evaporation rate is displayed here.
DEL
The time since last delivery is in hour units. There was no indication of a delivery during the problem period. All
tests rejected with error code 2 started within 2 hours of a delivery.
ULLG
The ullage factor is the surface area of the walls of the tank that is NOT covered in fluid. It is used for leak rate
compensation. This parameter normally provides little diagnostic value, but it actually solves the problem. An ullage
factor of zero indicates the tank is completely full, i.e., fluid height is equal to or greater than the tank’s diameter.
