Ion Science MiniPID - Manual (Page 10)

MINIPID 3PIN MANUAL Ion Science Ltd
Page 10 of 27
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Instrument interfacing
Mechanical installation
The mechanical considerations have been made simpler by designing compatibility with the standard LEL
sensor configuration, thus it is possible to plug the MiniPID into a standard 20mm diameter LEL sensor
position and the MiniPID detector will operate correctly, provided the OEM external signal conditioning circuit
can operate under the stated output specification range of the MiniPID.
Always ensure that the interconnect pins are fully seated and that the sensor is fully secure to prevent
unintentional movement or removal of the sensor by those unauthorised to do so.
Sealing the MiniPID
The MiniPID is designed to provide a good sealing area on the top face of the MiniPID. It is important that
your sampling line is well sealed to the MiniPID when measuring VOCs using a downstream pump. Refer to
the data sheet to ensure that you are sealing properly the PID without covering the gas access area.
The sealed cavity is defined by the window face at one end, through to the volume that contains the pellet
electrode stack arrangement and up to the PID filter front face. It is at this front face the OEM designer must
seal upon, ensuring that the seal lies within the three segmented arcs visible on the front face. This gives a
very small detector cavity of about 15 mm
3
that opens up many exciting possibilities for analytical work in
pump drawn systems.
Due to the potential for minor leakage through the layers within the cell do not exceed

500 Pa (5 mbar)
differential pressure between the PID and the gas detector internal cavity. This will ensure good signal
integrity (within 1%). Typically 5000 Pa (50 mBar) gives (10%).
Important note:
While every care has been taken to ensure that the lamp sits abutted against the underside of the visible
electrode, always ensure that the lamp is firmly pushed up against the underside of the visible electrode.
Should the lamp not firmly abut the front electrode (relative to the lamp) then the user will experience severe
degradation in accuracy (combined reduced signal levels and poorer linearity at high VOC concentrations).
Incorrect abutment will also cause a loss in pneumatic sealing.