en
Operation
4.2.2
Medium pressure breathing connection (LP)
CAUTION
The maximum input pressure of 10 bar is not permitted to be
exceeded in the medium-pressure version of the Air Guard
because the Air Guard can be damaged by higher pressures.
1. Use a CEJN connection (346 series) to connect the
Air Guard to the local system.
2. Pressurise the pipeline system.
4.2.3
Connection of the potential-free contacts
NOTE
The use of both potential-free contacts is recommended so
that filling with contaminated air is blocked in the event of an
alarm.
► Observe the technical data for using the potential-free
contacts (see chapter 9).
The Air Guard has two potential-free contacts. Using the
potential-free contacts, it is possible, e.g., to switch off a
breathing air compressor (not supplied) and to connect an
external shut-off device (also not supplied) in order to block
filling of contaminated breathing air. The contacts are located
on the internal terminal strip (X2 terminals 23 and 24 as well as
X2 terminals 26 and 27) and are closed in normal operating
mode. If there is an alarm or a malfunction or the Air Guard is
shut down, the contacts open.
NOTE
► When purging is initiated, the contact (X2 terminals 23 and
24) for controlling the compressor is closed so that the
connected compressor can be started. The contact (X2
terminals 26 and 27) remains opened so that when an
external shut-off device is activated, the contact will only be
opened again when the breathing air complies with the
standard.
► In Standby mode, contact (X2 terminals 23 and 24) for
controlling the compressor is closed, and contact (X2
terminals 26 and 27) for the external shut-off device is
open.
When the breathing air supply is turned on, an increased CO
concentration may occur. This happens especially after the
compressor has been idle for a longer period of time. In this
case, activate the purge to restore the Air Guard to its
operating condition. To purge the line, purging must be
activated on the Air Guard touchscreen. When purging is
activated, the contact (X2 terminals 23 and 24) for controlling
the compressor is closed so that the compressor for purging
can be started.
1. Connect the potential-free contacts to the external alarm
system or component.
22
4.2.4
Electrical connection
WARNING
The electrical system may only be installed by qualified
electricians.
1. If necessary, connect the potential-free contacts.
2. Insert the power plug of the Air Guard into the earthed
power socket.
NOTE
It is recommended that the circuit breaker in the mains supply
line should have the following characteristics:
16 A, characteristic B.
3. Turn on the circuit breaker.
4. Close and lock the door of the Air Guard.
4.2.5
Calibration
Gas detector
CAUTION
The Air Guard must be calibrated before use to prevent
erroneous measurements.
► Calibration may only be carried out by Dräger or by Dräger
authorised technical personnel.
The electrochemical gas sensors for the Polytron gas
detectors are supplied unmounted along with the Air Guard in
order to increase the life span and must be installed before
calibration. For instructions on how to install them, refer to the
instructions for use of the respective gas detector and sensor.
The respective gas sensor must be allowed to warm up for a
while after it is inserted in the gas detector. The exact warm-up
time can be found in the corresponding instructions for use.
The gas detectors can then be calibrated. It is recommended
that the Air Guard be turned on before calibration so that the
wait time up to calibration by Dräger Service or the authorised
technical personnel is as short as possible. The PIR 7200 and
the PID 5000 are optical gas detectors which do not require
sensors.
1. Calibrate the zero-point as described in the instructions for
2
use.
2. Calibrate the sensitivity as described in the instructions for
use.
The calibration gas suitable for the sensor must be used to
adjust the sensitivity. Select the concentration according to the
measuring range of the sensor (see chapter 10).
Oil sensor
Calibrate the oil sensor using isobutylene as described in the
instructions for use included in delivery. This work may only be
carried out by Dräger or by authorised technical personnel.