MSA MultiGard 5000 - Page 24

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3103-1001 Rev. 0
3.4 Dwell Time Parameters
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.
WARNING
Entering correct Dwell Time Parameters is critical to proper system
operation. Incorrect entries may lead to a hazardous situation.
Contact MSA if you have any questions related to the MultiGard
5000 Gas Sampling System Dwell Time Parameters.
The components make up the dwell time of the MultiGard 5000 unit on a sample point are referred
to as the dwell time parameters. These parameters are the sample transport time for the specific
point, the system internal transport time, the sample analysis time, and extended analysis time. The
sample analysis time and extended analysis time are entered in the Extended Setup/Sample Transport
Time screen (see section 4.2.6). These two factors are to be set in conjunction with the extended
analysis time trigger.
Table 3.3 is provided to assist in determining the appropriate dwell parameters. For each sensor
indicated, three options are provided; A, B and C. Selecting option A will require a longer cycle time
for the system but provide the least wear on the sample and bypass solenoid valves. Selecting option
C will allow for a shorter cycle time for the system leading to a quicker response to a leak at the
expense of decreasing the life span of the sample and bypass solenoid valves. Option B represents a
compromise between options A and C. Select the option which best suits your gas detection
requirements.
Examine the same row for each sensor to determine the slowest responding sensor in the MultiGard
5000 Gas Sampling System. Select one of option A, B or C for that sensor. Enter the analysis time,
extended analysis time and triggers for extended analysis time associated with the option selected.
For analysis time, use the column with the sample flow rate recommended for your specific system.
The analysis time and extended analysis time are common to all sensors. The triggers for extended
analysis time are independent for each sensor.
For the other sensors, select the option that has the longest analysis time that is less than the analysis
time for the slowest responding sensor previously determined. Enter the extended analysis triggers
for that sensor indicated by that option. Repeat this process for all the other sensors that may be
installed.
Refer to Section 1 and/or Section 3 for dwell time for any sensor/analyzer not indicated in Table 3.3.