MSA MultiGard 5000, Manual

Page: 28 / 132

20
3103-1001 Rev. 0
3.5 Actual Dwell Time
NOTE: Sections 3.3, 3.4 and 3.5 specifically apply to the standard MultiGard 5000 look-ahead
bypass flow scheme. Refer to Section 1 if your system employs a custom flow scheme.
The purpose of the look ahead bypass is to draw on the next sequential sample line to reduce or in
some cases even eliminate the sample transport time. The processor continuously uses the dwell time
parameters and the
actual programmed sampling sequence to determine the actual dwell time. For
every line, the actual dwell time is calculated according to the following formula:
Actual Dwell Time (line
n ) = Sample Transport Time (line n ) - Dwell Time of Previous Position in
Programed Se Internal Transport Time + Analysis Time + Extended Analysis Time
NOTE: The previous position should be verified in the actual programed sampling sequence.
With precautions taken such that the minimum actual dwell time is never less than the sum of the
analysis time, extended analysis time and internal transport time.
The internal transport time is a factory configured constant that is determined to be the time required
to transport the sample from the sample manifold to the sensor(s). The internal transport time for this
system is 10 seconds.
The extended analysis time is only a factor if triggered by a preset rate or level condition.
The actual dwell time of the current sample point is displayed on the Sequencer Control display
screen (see section 4.1.6).