IS-HF-AirSentinelIII-100123 Rev 0
6
Operation
The Air Sentinel III purge controller is mounted on the side of the
main enclosure. This controller will ensure proper safe operation of
the attached equipment. If all of the required conditions are met, the
controller will act as a power governor. It does this by monitoring the
pressurization of the main enclosure with clean, dry air. The Air
Sentinel III has three indicator lamps. Should the air supply pressure
fail, the top lamp on the Air Sentinel III unit will turn RED and power to
the rest of the instrument is disconnected.
Startup
When power is applied to the Air Sentinel III for the first time, ensure
that the air supply is connected as stated in the Installation and
Commissioning section earlier in this manual. Also ensure that the
main enclosure is closed and locked. Once power is supplied to the Air
Sentinel III, it will run through an automatic seven-minute purge cycle
before supplying power to the rest of the system. During the purge
period, the Air Sentinel III’s Timer lamp will be RED indicating the purge
is in process and no power is output.
At the completion of the purge, the Timer lamp will go GREEN and
power will be applied to the rest of the system. As long as the proper
air supply conditions are met, the Air Sentinel III will continue to
operate.
Indicator Lamps
The Air Sentinel III indicator lamps are a very quick way to determine
operation of the controller and the safety condition of the connected
instrument or equipment.
The Air Sentinel III has three LEDs that can be either RED or GREEN.
Lamp Color Matrix
Operation
Power to Instrument
All lamps
GREEN
Safe Operation
ON
TIMER Lamp
RED
Instrument is purging.
OFF
PRESSURE Lamp
RED
Unsafe operation, pressure low.
OFF
Bypass Lamp
RED
Bypass key operating.
ON
Using the table above, you can quickly determine the operating
condition of the power out. Under normal, safe operation, all lamps
should appear
GREEN
.
Do not apply power to the Air Sentinel III purge controller unless
the area has been properly tested and is known not to contain
explosive materials.
DANGER
!
After power is applied, the Air Sentinel III requires 10 seconds to
respond while it runs a self-test.
NOTICE
This lamp indicates if the minimum
enclosure pressure is met.
This lamp indicates if the timer is
enabled.
This indicates if the Bypass Key has
been used.
Maintenance Bypass Operation
To perform some maintenance operations on the enclosed equipment,
it may be necessary to have the enclosed equipment powered up while
the enclosure door is open. Under these conditions, normally the Air
Sentinel III purge controller would determine that the enclosure is not
pressurized and power would be removed to the equipment. To allow
for this situation, a special maintenance bypass key is supplied.
Located on the front of the Air Sentinel purge controller is a knurled
cap. Removing this cap reveals the key slot. Insert the key, push
in slightly and turn it clockwise to engage the bypass operation.
The BYPASS lamp will turn RED to indicate entering bypass mode.
Assuming the atmosphere around the enclosure has been tested and
known to be safe, the enclosure door can now be safely opened and
power will remain on to the entire system. The key cannot be removed
while operating in the maintenance bypass mode.
To return the Air Sentinel III to normal, safe operation, close the
enclosure door. Ensure that the air supply is connected, turn the key
counter-clockwise and remove. Replace the knurled cover. If the
pressure in the cabinet has built up to a normal acceptable level, the
instrument will continue to run.
Programming
The Air Sentinel III is factory programmed for the application to ensure
that during purge, at least five volumes of air are exchanged during the
Timer period. This will vary with internal pressure and the volume of the
enclosure that the system is operated at.
When used in the HF scientific AccUView LED Ex, the purging time is
set to 7 minutes.
Each Air Sentinel III is factory programmed and checked for flow rate,
internal (enclosure) pressure and timer period.
To meet the requirements of the IEC 60079-2, the minimum
overpressure is 50 Pa or 0.5 millibar. This pressure should be regulated
with an internal pressure regulator.
Use of the bypass key disables the safety features and safe
operation of this instrument. It is very important that the
operator checks the operating atmosphere and determines that
it is safe before opening the enclosure. This is intended as a
temporary operating condition.
DANGER
!
Do not operate the Air Sentinel III for long periods of time in the
bypass mode. This is intended only for maintenance operations.
Do not operate the Air Sentinel in the bypass mode unattended.
DANGER
!
To ensure safe operation, the information for intended operating
pressure, flow rate and timer (purge) period must be sent to
HF scientific as part of the order so the Air Sentinel III can be
programmed accordingly.
NOTICE
