6500 Series Purge and Pressurization System
I/O Manual
37
For dilution to properly be applied, the 6500 system would have to use the continuous vent
measures the pressure and flow across an open orifice plate inside the vent to give flow vs. pressure
curves for setting up the dilution requirement. For the setup, the 6500 will purge the enclosure at a user-
set flow rate and after purging, the flow will settle at a user-set dilution flow. From the flow curves for
each continuous vent. The 6500 menu also has a MIN FLOW SP (minimum flow set-point) that can be
used to alarm the user if the dilution flow is too low. For shutting down the system, from the vent flow/
pressure curves, the enclosure pressure for the shutdown flow in the curves can be used for the minimum
overpressure value for de-energizing enclosure contacts.
Below is an example of a dilution application. In this example, the user has set up the enclosure for a
dilution area as shown above and has calculated the required flow for dilution by knowing the normal and
abnormal releases.
Equipment used:
• 6500-01-… control unit
•
• 6500-MAN-PV-01 proportional valve
• 6500-CBLG-… cable gland set for 6500 control unit (optional)
Required flow for dilution = 45 l/min
From the 6500 menu for purge settings, the following dilution parameters are selected. All of these
parameters and set-points are user selectable.
MENU PARAMETER DESCRIPTION
VENT FLOW CONTROL Dilution User is going to set up system for dilution
VALVE CONTROL Proportional Proportional valve output on the 6500 control
unit will be used
DILUTION SETTINGS Sets up set-points
Purge Flow The flow rate for purging the enclosure by
the proportional valve
Dilution Flow SP The flow rate for dilutions. This value should
be higher than the minimum required flow
because of variations in line pressure and
reaction time of the PV
Min Flow Sp If the flow rate drops below this set-point,
alarm is generated
PRESSURES Min Overpressure The pressure associated with the minimum
flow for dilution to shut off the enclosure
contacts
Max Overpressure Maximum enclosure pressure will adjust PV
below this value
flows. From these curves, if it is required to shut power off to the enclosure if flow drops below the
minimum flow rate for dilution, then this pressure for the flow is selected for the minimum overpressure
value.
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