WIKA CPB3800 - Handbuch (Seite 39)

39 WIKA operating instructions model CPB3800
14062232.03 12/2013 GB/D
GB
7. Maintenance, cleaning and recalibration
Weights are made of austenitic stainless steel which are entirely stable. They should be
periodically cleaned using a non abrasive method to remove any foreign matter.
7.4.2 Need for overhaul and re-certification
We recommend that the pressure balance be returned to us for overhaul and
re-certification at any time if when used in accordance with instructions:
1. The piston does not spin freely.
2. The rate of fall of the piston is appreciably greater than when new and makes use of
the pressure balance difficult.
3. The weights are damaged.
4. The pressure balance cannot be made to operate satisfactorily due to wear or
damage to pump piping or valves which cannot be rectified by the user.
This pressure balance can be used for calibration of instruments with an expected
accuracy of 1, 0.5 or 0.25 %. Such pressure balances need not be sent back frequently
for overhaul and re-certification and provided they are working well can be trusted for
many years. Under these circumstances, an interval of five years might be appropriate
between overhauls.
When high accuracy of the pressure balances is required, it should be returned for
overhaul and re-certification more frequently. The actual period will depend on how the
pressure balance is used. A pressure balance kept in a laboratory and carefully used
might need to be returned every two to five years. A pressure balance carried from site
to site and used for calibrating high accuracy gauges or transducers from industrial
process plant or for measuring pressures directly might well need to be returned at
intervals of less than specified above.
The actual period between overhaul and re-certification should be fixed by the user in
the light of the above comments taking into account the requirements of any inspection
authority, which might be involved.
7.4.3 Identification of weights
All weight sets supplied with a pressure balance have allocated, and are marked, with
a weight set number. Additionally, if users wish to ensure that only specific weights are
used with an individual pressure balance or piston and cylinder unit, then the serial
number of the pressure balance, and/or piston-cylinder unit may also be marked on the
main weights. Regrettably due to size of certain weights, not all the above information
may be marked.