Instruction Manual MIC type EC-912
Revision no.4
29 / 38
Periodical calibration of the MIC
To ensure that the MIC measures correctly we highly recommend calibrating your MIC system, in
regular intervals no longer than 2 years, against FORCE Technolog
y’s world reference MIC for smoke
measurements.
The test procedure, the setup and the results of the smoke calibration are documented in 2 Certificate
of Calibration
– one measured before cleaning, and one measured after .
The MIC contains a radioactive source and the manufacturer specifies that the RWL (Recommended
Working Life) of the source is 10 years calculated from the date of first use. However the life time may
be extended, when routine inspections are performed on a regular basis.
Before we deliver any MIC, the radioactive source is examined and checked for any leakage by
executing a WIPE-test according to ISO 9978:1992, clause 5.3.1.
The WIPE test of the radioactive source ensures that the MIC is safe to use for a period of up to 2
more years.
Note:
Before the smoke calibration, the electrode distance and the active area of the
radioactive source of the individual measuring ionization chambers have been adjusted.
So the serial number of the radioactive source must correspond to that of the MIC.
Possible errors and hints
Flow system
If it is not possible to adjust the flow rate on the flow meter to 30 l/min then there is either a leak or a
block in the VP, the FCU or the hose connections. First check the performance of the VP and the FCU
as described in Section 2.1.3 point i) to l) by using a short new piece of hose. If the performance of the
VP and FCU is OK there is either a leak or a block in the hose connections. Inspect the hose
connections for a possible leaks or blocks and replace the damaged hose connection. If the
performance of the VP and MCU is not OK then there is probably a block in the filter for the MCU, in
the flow meter or in the filter for the VP. Refer to Section 5.1.3 for cleaning of flow meter and exchange
of filter element in the FCU.
Electronics
The mains fuse is located in the mains plug assembly which is placed on the left side of the rear part
of the CC. First remove the mains plug and then remove the fuse holder with a screwdriver.
Recorder output X should follow the reading on the display with a factor of 10. If this is not the case
then either the load impedance on the recorder output is to low (load im-pedance >100 k
Ω) or the
AMCU / IMCU electrical circuit is malfunctioning. Refer to Section 5.4 if the latter is the matter.
If the chamber voltage Uc necessary for calibrating the MIC is greater than 25 V, the radioactive
source is probably covered with smoke deposits and needs cleaning. Refer to Section 5.1.1 for
cleaning of the radioactive source.