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Explosion protection
DESIGN OF THE CLASSIFIED
There are three different areas in the chromatograph
with respect to the explosion protection:
Pressurized area
This includes the electronics area, the mounting shaft
behind the analyzer section, the connections of the oven
heating cartridge and the connection cables of the FID.
Carrier gas H
must never be passed into this area.
2
Switching valves for carrier gas H
fitted outside this area: classified solenoid valve in the
mounting area, or pneumatically-controlled slide valve.
Flameproof area
The housings can resist an internal explosion pressure.
Flames are not released because they are cooled down
below the ignition class temperature on their way out.
These include the FID, TCD and solenoid valves.
Potentially explosive atmosphere
The surface temperatures in the oven area and the
mounting area above the oven are limited to tempera-
ture class.
Degrees of protection used
A rating plate which specifies the degrees of protection
is present on the housing of your classified chromato-
graph:
Electronics area
Oven heater
FID
TCD
FDV
FPD
Detector heater
Heated line
Solenoid valve for H
2
and flammable samples
Safety monitoring unit
Heaters for oven,
liquid injection valve and heated line
Each heater contains a temperature limiter in addition
to a heating cartridge and temperature sensor. The
limiter switches the heater off shortly before the igni-
tion class temperature is violated.
The electrical connections have a pressurized enclosure.
They are routed into the mounting shaft via a purged
tube. Exhaust openings in the flange ensure good venti-
lation.
10
PGC 302
must therefore be
2
EEx pe IIB+H
2
EEx pd IIB+H
T2/T3/T4
2
EEx dp IIB+H
T2/T3/T4
2
EEx de IIB+H
T3/T4
2
EEx pd IIB+H
T2/T3/T4
2
EEx pd IIC T3/T4
EEx pd IIB+H
T2/T3/T4
2
EEx p IIB+H
T3/T4
2
EEx de IIB+H
T5
2
EEx de[ib] IIC T4
Electronics
Detector,
flameproof
Heaters
Solenoid valve for carrier gas H
The solenoid valve is classified. The connection cables
are potted.
Classified FID
The detector has no own heater and is classified. The
gas inlets and outlets act as flame barriers. They prevent
sparks from passing outside the heating chamber.
The electrical connections have a pressurized enclosure.
They are routed into the mounting shaft via a purged
tube. Exhaust openings in the flange ensure good venti-
lation.
Classified TCD
The detector has its own heater and is classified. The
gas inlets and outlets act as flame barriers. They prevent
sparks from passing outside the measuring chamber.
The electrical connections are present in a classified
junction box.
A temperature limiter is fitted in the detector housing
because the bridge current additionally heats the detec-
tor. The limiter switches off the bridge current shortly
before the ignition class temperature is reached.
Oven
2
1EXPLO.CHP, Stand Dezember 22, 1999
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