||- MTH 65
- Ver 4
and Maintenance of the Analytical Balance
Safety Checks - Daily:
- The Metcalfe Digital Analytical Balance has a service
contract and is serviced regularly by Metcalfe Servicing
Division. For malfunctions and servicing beyond the calibration
and routine care items listed below, call Metcalfe Servicing
Division on 9555-8888 and quote Service Contract number
- When the balance is unserviceable, attach a 'Balance Unserviceable'
tag to the front of the weighing cabinet and disconnect
the power lead. Annotate the Equipment Log accordingly and
advise the Senior Technician.
Set-up and Pre-use Checks - Daily:
- Check that electrical connections are fully coupled, that
cords are not frayed and that there is no liquid on or about
- Under NO circumstances is any staff member of SimuLab
permitted to open the sealed electronic unit of the balance
or attempt any procedures not listed below.
- Unidentified spilt chemicals should be removed with extreme
caution whilst wearing standard SimuLab PPE (for details
of cleaning, see the cleaning section below).
Calibration Checks - Bi-annually:
- Ensure that the Instrument Room and the balance doors
are closed to minimise draughts.
- Check the level, and if necessary, level the balance using
the leg ferrule adjusters and the in-built spirit level.
- Turn the balance on at the wall and press the Start button.
- Allow five minutes for the electronics to warm up.
- Press the Zero button and ensure that the balance reads
0.0000 +/- 0.0003 g. Press the Zero button once more to
place the balance into Standby mode. An orange Standby light
will now glow
Cleaning - Daily or as required:
- Press zero button and check that digital readout reads
0.0000 +/- 0.0003 g within 4 seconds. Repeat once if digital
readout fails to display 0.0000 g within 4 seconds.
- Press the calibration button. The balance will run through
a calibration and zeroing check procedure and signal 'Cal
OK' in the digital readout. If Cal OK does not appear within
one minute, repeat the procedure once.
- Check the Accuracy of the balance by carefully
weighing check weights, which are located in the marked
box in the drawer adjacent to the analytical balance.
Always use the forceps provided to handle the calibration
weights. Do NOT handle weights with fingers. Use weights
1.0 g and 0.01 g. Acceptable ranges for each of the weights
1.0 g: 0.9980 - 1.0020 g
0.01 g: 0.0090 - 0.0110 g
Always weigh the 1.0 g weight FIRST.
- Check the Precision of the balance by weighing
the 1.0 g weight consecutively ten times. Calculate the
standard deviation (SD). Acceptable SD is up to 0.02, g.
- If the balance fails any of the four checks above, contact
the Metcalfe Servicing Division.
- Return the balance to Standby mode.
- Carefully remove the balance pan, clean and replace it.
- Mop up any spilt liquids and brush any spilt chemicals
from the weighing chamber. Clean the glass doors (inside
and out), using a soft cloth and 80% v/v ethanol.
- Remove dust from the exterior of the cabinet and clean
up any spilt chemicals from the balance bench area.
- Details of all routine maintenance, malfunctions and repairs
shall be kept in the Equipment Log.