Freon Application Operations - Scanivalve DSA3217-PTP Series Operation And Service Manual

DSA3200-PTP
Purging
All DSA-PTP modules incorporate an internal calibration
valve. One of the configurations of this valve allows for an
'isolate-purge' feature. This permits the pressure measure-
ment (Px) lines to be purged with pressures 50psi over the
full scale module pressure up to 500psi during test. If the
module range is greater than 500psi it is not recommended
to purge during test. It is not recommended to purge at
greater than 100psi when purging to atmosphere. This is
a very useful feature when the DSA-PTP module is used in
applications where corrosive gasses or moisture may be
present in the input lines. By isolating the pressure sensors
from the purge pressure, even low pressure DSA-PTP mod-
ules can be purged safely with high purge pressures.
In order to configure the DSA-PTP module for purge mode
90-120 psi of control pressure must be applied to the 'CTL1'
'CTL2' and 'PRG' ports. The purge mode must be estab-
lished in a set order in order to protect the sensor and
calibration modules from damage.
Configuring for purging:
1. Set the calibration valve for calibration mode by
applying 90-120 psi of control pressure to both the
'CTL1' and 'CTL2' ports.
2. Apply 90-120 psi of control pressure to the
'CTLPRG' port.
3. Apply the purge pressure to the 'PRG' port.
Re-configuring after a purge:
1. Shut off the purge pressure feeding the 'PRG' port.
Make sure to allow sufficient time for the input
lines to stabilize. The specific time required will
depend upon the physical layout and characteristics
of the system.
2. Remove 90-120 psi control pressure from the
'CTLPRG' port.
3. Remove the 90-120 psi control pressure from the
'CTL1 and 'CTL2' ports.
CAUTION! Failing to follow the above
procedure while entering or exit-
ing the purge mode could allow the
sensor to see the high purge pressure
and could seriously damage the DSA-
PTP module

Freon Application Operations

When using DSA3218-PTP modules in Freon Applications
special considerations must be taken. In order to prevent
premature deformation of the seals within the DSA3218-
PTP's valve, it is important to leave the module in the
following 'dormant' state.
• Apply CTL2 and PRGCTL pressures
• Ensure no Px pressures are applied
• Freon present must be vaporized
Any time the module will be left inactive for a significant
period of time it should be left in this state. Adhering to
this procedure will help ensure long life and prevent any
premature maintenance requirements.
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Section 3: Operation