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14
Set Zero Flow
On some applications and in some conditions it may be that although there is no flow the instrument may show a small
offset due to system noise. The offset can be cancelled out and will increase the accuracy of the instrument. Selecting
this option and pressing
ENTER
the display will show the following.
Stop the flow
COMPLETELY and
press ENTER or
SCROLL to cancel
Pressing
ENTER
before the flow has stopped will result in an error message asking if you
are you sure the flow has
stopped
. This occurs when the flow is still above 0.25m/sec.
When this facility has already been selected, press
ENTER
to cancel the previous instruction, then it is possible to re-
set the Zero balance. The option is not available when error messages E1 and E2 (See page 17) are being displayed.
Total
This option allows the user to disable the positive and negative totalizers. When you select either of these options the
totaliser will start or stop functioning. It does not zero the total, this is a separate function described below.
Reset + Total/- Total
The Portaflow 216 has forward and reverse totaliser that can be reset when this facility is selected. Use the scroll keys
to select and press
ENTER
to reset. The Total is stored when the unit is switched off or battery goes flat, therefore may
need to be reset before each use.
Damping (sec)
This facility is used when the flow readings are unstable due to turbulence caused by obstructions or bends etc.
Damping or averaging can be used to make the readings more stable. It can be set to up-date the display, anything
between 3 and 100 seconds.
Calibration Factor
If for any reason the instrument goes out of calibration and the readings may be higher or lower than normal then this
facility enables the user to correct the reading. If for example the reading is 4% higher than normal then entering 0.96
will reduce the reading by 4%. If the reading is 4% lower than normal then entering 1.04 would increase the reading by
4%.
When the instrument is supplied it will always default to 1.00 and when this is changed it will stay in the memory to
whatever it has been changed to, until such time as it needs to be changed again.
Correction Factor
This is a facility that can be used when errors occur due to lack of straight pipe or the sensors have been placed too
close to a bend, this could give an incorrect reading to what is expected. The user can set this as a % in the same way as
the calibration factor, but it will not be stored in the memory.
Diagnostics
Calculated µ
µµ
µs
This is a value the instrument predicts will be the time in
µ
secs that it should take for the transmitted signal to go across
a particular pipe size. This value is ascertained from the data entered by the user. i.e. Pipe size, material, sensor set etc.
Up
µ
µµ
µ
s, Dn
µ
µµ
µ
s
This is the actual transit time measured by the instrument and will be slightly (5-10
µ
s depending on the pipe size and
signal condition) less than the calculated value above.