P2.x AMEX
4.4.1.2 Monitoring measures when conveying flammable and/or toxic gasses
Conveying flammable and/or toxic gasses
further requires
continuous monitoring
of the sample gas
pump during operation.
This can be done as follows (1) or (2).
1.
Flow rate monitor before the pump’s gas inlet and after the gas outlet. A sudden reduction of the suction volume / flow
volume ahead of the pump and consistent or suddenly increased flow volume after the pump indicates a defective bellow
(the pump can convey ambient air suctioned in due to the tear).
2.
Vacuum monitoring before the pump’s gas inlet and flow monitoring after the gas outlet (see illustration). A sudden drop
in the vacuum before the gas inlet indicates a defective bellow.
When conveying flammable gasses above the upper explosive limit (UEL) we further recommend monitoring the lower explosive
limit (LEL) in the installation location.
When conveying toxic gasses we recommend MAC monitoring (MAC: Maximum Workplace Concentration) at the installation
site.
underpressure
manometer
sample gas pump
manometer
flowmeter
shut-off valve
Fig. 1: Sample flow diagram of suitable monitoring
4.5 Electrical connections
WARNING
Hazardous electrical voltage
The device must be installed by trained staff only.
WARNING
Inverter operation is forbidden!
WARNING
Regard National directives concerning installation and operation of electrical devices in
hazardous areas when installing and commissioning the motor (e. g. EN 60079-14).
CAUTION
Wrong mains voltage
Wrong mains voltage may damage the device.
Regard the correct mains voltage as given on the type plate.
A switch or circuit breaker (per approval) must be installed for the sample gas pump. It must be easy for the operator to reach.
The switch must be marked as a cut-off for the device. It mustn't be integrated into a supply cable or interrupt the earth con-
ductor. It must further separate all poles of the sample gas pump from live parts.
Only operate the unit with the factory installed motor. The user must not exchange the unit or replace it with a different motor.
The sample gas pump must be protected against prohibited heating with suitable overload protection (protective motor switch
per approval).
Please note the rated current for the protective switch settings (see motor type plate).
Verify the pump motor has the correct voltage and frequency: Voltage tolerance ±5 %, frequency tolerance ±2 % - from rated
value.
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Bühler Technologies GmbH
BE420003 ◦ 08/2021
