Kendro HERAcell 150 - Metering and Regulation Circuit

Name/Name Datum/Date Benennung/Designation
Erstellt/Prepared
D.Dornseiff 01/15/98
Index Änderung Name/Name Datum/Date
Service Handbuch HERAcell 150
Service Manual HERAcell 150
C 202613 D.Dornseiff 06/26/03
Dokumentnr./Document No. Seite/Page
Datei/File
50051109_04_EN_C.doc 50051109 / C 30/ 9
Weitergabe sowie Vervielfältigung dieser Unterlage, Verwertung oder Mitteilung ihres Inhalts nicht gestattet, soweit nicht ausdrücklich zugestanden. Zuwiderhandlungen ver-
pflichten zu Schadensersatz. Alle Rechte für den Fall der Patenterteilung oder Gebrauchsmustereintragung vorbehalten. © Kendro Laboratory Products GmbH, Germany
4.7.6 CO
2
METERING AND REGULATION CIRCUIT
Short description:
The replaceable, connector-compatible, thermal conductivity detector (TCD with
auto-zero or infrared (IR) sensor) is integrated in the sensor block. CO
2
regulation
is µP-based
CO
2
gas input is metered by a solenoid. The gas flowrate is also restricted by a
capillary opening with a diameter of 0.7 mm, integrated in the valve block. Before
entering the unit, the gas passes through a sterile filter that can be accessed from
outside the unit for replacement.
TCD:
In units equipped with the O
2
option, a cross-sensitivity of the O
2
concentration in
the sample chamber to the CO
2
measured value must be taken into account. The
compensation has been factory preset for new units. The steps required to check
this setting or when replacing the measuring cell are described in Section 4.14.3.
IR Sensor:
IR-absoption-sensor with auto-zero function for automatic zero-point correction of
drift and grow old.
Selection of the wavelenght with two different filters.
Compensation of the barometric influence with an internal pressure sensor.
Finding of the CO2 value in the microcontroller of the sensor.
Circuit diagram:
See circuit diagrams in Chapter 3.
Technical specifications:
Gas flowrate: ~ 5 l/min
Gas input pressure: 1 bar