Siemens SIPROCESS GA700 Compact Operating Instructions page 56

Connecting
4.7 Connecting the wall-mounted device
Minimum requirements for explosion protection with pressurized enclosure
In principle for IEC/ATEX applications, any Ex px, Ex py or Ex pz safety equipment with a type
test certificate for hazardous areas can be used.
This safety equipment must have at least the following features:
• Safety level for monitoring:
– During pre-purging: At least to Category 3 from EN ISO 13849-1
– During operation: At least to Category 1 from EN ISO 13849-1
– or to other comparable international standards.
• Adjustable automatic pre-purging phase for Ex px/py: Purging gas flow must be at ≥ 60 l/min
• Limitation of purging gas pressure during the pre-purging phase: < 110 hPa relative
• Purging gas flow must be a monitored to be more than >= 1 l/min
• Connection of purging gas lines: ∅ 12 mm (0.47 inch) from/to analyzer
• For Ex px: Relay contacts for all-pole isolation of the analyzer's power supply (inrush current
>50 A)
• For Ex px: Relay contacts for disconnecting additional equipment (e.g. Ex isolating relay)
• Access protection against unauthorized persons
Suitable Ex px safety equipment is shown in the section "Ex px safety equipment (Page 107)"
using a pressurized enclosure system as an example.
For flammable gases we recommend Ex px, as otherwise, all electric circuits for power
supply, signals and communication must be manually switched off in the event of the failure
of purging.
Further information on the Ex p purging
When discharging purging gas ensure that the pressure drop via the exhaust air line does not
result in the following components switching off:
• Ex p safety equipment during the pre-purging phase
• Analyzer during the operating phase
To achieve this, the exhaust air line must be dimensioned accordingly (for example with an
inner diameter of G1", the length of the exhaust air line may be about 20 m).
• Always adhere to the pre-purging time that can be set at the Ex p safety equipment.
The pre-purging time amounts to 10 minutes at a purging gas flow rate of 60 l/min.
• Do not supply sample gas to the analyzer until the pre-purging phase has ended.
• OXYMAT 7: Before sample gas is supplied, the microflow sensor must be reliably flushed by
reference gas. The reference gas must therefore also be connected (pre-purging period -
10min) when the Ex p safety equipment is switched on.
Note that the reference gas pressure must always be 2000 hPa (± 150 hPa) above sample gas
pressure.
56
SIPROCESS GA700 rack and wall mounted devices
Compact Operating Instructions, 06/2023, A5E35134047-AB