Operating instructions

6. Maintenance page 71
Mercury Instruments UT-3000-E_V2.11.docx 31.07.12
Analytical Technologies
The Automatic Calibration Unit has two main fuses which are located in the fuse compartment.
This is located on the rear of the instrument between the power cord receptable and the power
switch.
Pull power plug before opening the fuse compartment!
Fuse type: The rating of the fuses to be used as spares depends on the operation voltage
indicated on the rating plate of the instrument:
230V Operation voltage: Fuse type T 1.0 A (time lag)
115V Operation voltage:
6.7 Cleaning the GoldTrap
In some cases the sensitivity of the analyzer may be clearly reduced compared to the new
instrument and the measurement signal gets weak. One reason for this may be a contamination of
the GoldTrap. One may try to remove this contamination by rinsing the inside of the GoldTrap
with concentrated nitric acid.
WARNING: Nitric acid is a toxic, harmful, dangerous and corrosive
reagent. Only personnel which has been sufficiently trained in working
with such chemical substances is allowed to handle nitric acid and to
perform the following steps!
Concentrated acids shall be handled in a fume cupboard!
Protective laboratory clothes, safety goggles and laboratory gloves have
strictly to be worn!
The GoldTrap has to be uninstalled following the steps in chapter 7.6. Over both ends of the thin
ceramic tube which poke out from the aluminium cylinder a suitable plastic tubing (PVC,
Tygon®) is pushed so that a tight connection is formed. The plastic tubing on one end shall be
long enough to reach the bottom of a 50 ml or 100 ml glass beaker. The plastic tubing on the
other end is connected with the tip of a plastic syringe (a 10 ml medical syringe will work).
Approximately
20 ml of concentrated nitric acid are filled into the glass beaker (fume hood!). The GoldTrap-
Syringe assembly is positioned over the beaker so that the free end of the tubing dips into the
nitric acid. The piston of the syringe is pulled carefully and slowly so that nitric acid is sucked
through the GoldTrap and appears in the syringe. After waiting for approximately 30 seconds the
acid is pushed through the GoldTrap the other direction by pushing the piston of the syringe.
Care has to be taken that no acid splashes out from the beaker.