Results (
Thai) 2:
[Copy]Copied!
United Kingdom Accreditation Service, 21-47 High Street, Feltham, Middlesex, TW13 4UN
Website: www.ukas.com Publication requests Tel: 020 8917 8400 Fax: 020 8917 8500
© United Kingdom Accreditation Service 2009. UKAS Copyright exists in all UKAS publications
PAGE 4 OF 11
(iii) the letters Ex (In for volumetric flasks), to indicate that the glassware
has been adjusted to deliver (or contain) its indicated volume;
(g) multi-mark pipettes of the blow-out type shall be marked with an etched white ring
and marked as blow-out.
2.4.3 If a particular item of glassware is not marked in accordance with the relevant British
Standard, then it does not conform to that standard.
2.5 CALIBRATION INTERVALS
2.5.1 The capacity of volumetric glassware may change with use. Particularly where the
application warrants Class A glassware, the calibration should be verified at regular
intervals. The interval will depend on the extent and nature of usage and should be
determined by experiment so that re-calibration may be performed before the
apparatus fails to perform to specified requirements. Initial calibration intervals
should not exceed one year.
2.6 CALIBRATION REQUIREMENTS
2.6.1 For most procedures, it is reasonable to expect that volumetric errors will be
cumulative and thus dependent on the number of volumetric steps involved. If the
testing procedure requires the measurement of a liquid volume to specified accuracy,
then the volumetric glassware need not be calibrated if its specified maximum
permissible error does not exceed one fifth of the specified accuracy for the
measurement. For example, if there is a requirement to measure a volume of
100 cm 3 to 0.1 cm 3 , there is no need to use glassware which has been calibrated, if
the glassware’s maximum permissible error is < 0.1 cm 5, that is 0.02 cm 3 .
2.6.2 In Table 1, four error ranges have been assigned for one-mark volumetric glassware,
based on the maximum overall error permissible in the analytical procedure. These
do not apply to multi-mark volumetric glassware (such as graduated pipettes and
burettes) for which tolerances are generally less strict. For these, two further error
ranges have been defined (see Table 2).
2.6.3 Tables 1 and 2 also list glassware by type against the assigned error ranges, and
indicate which sizes of glassware require specific calibration before use.TRACEABILITY: VOLUMETRIC APPARATUS LAB15 | EDITION 2 | JUNE 2009
United Kingdom Accreditation Service, 21-47 High Street, Feltham, Middlesex, TW13 4UN
Website: www.ukas.com Publication requests Tel: 020 8917 8400 Fax: 020 8917 8500
© United Kingdom Accreditation Service 2009. UKAS Copyright exists in all UKAS publications
PAGE 5 OF 11
Table 1 Error ranges for one-mark volumetric glassware
Error
range
Permissible overall
error in analytical
procedure*
Maximum specified
tolerance for
volumetric glassware*
Glassware usable without prior calibration
1 0.1% () 0.02% None
2 0.1-0.5%, mean 0.3% () 0.06% Certified volumetric flasks
Class A, capacity at least 250 cm 3
Uncertified volumetric flasks
Class A, capacity at least 2000 cm 3
Certified bulb-pipettes
Class A, capacity at least 200 cm 3
3 0.5-1.5%, mean 1.0% () 0.2% Certified volumetric flasks
Class A, capacity at least 25 cm 3
Uncertified volumetric flasks
Class A, capacity at least 100 cm 3
Certified bulb-pipettes
Class A, capacity at least 10 cm 3
Uncertified bulb-pipettes
Class A, capacity at least 50 cm 3
4 > 1.5% eg > () 0.3% Certified volumetric flasks
Class A, capacity at least 10 cm 3
Uncertified volumetric flasks
Class A, capacity at least 25 cm 3
Certified bulb-pipettes
Class A, capacity at least 5 cm 3
Uncertified bulb-pipettes
Class A, capacity at least 20 cm 3
* This data has been adapted from procedures outlined in an MOD MQAD Calibration Bulletin (#11),
published in January 1978 and amended in June 1978. This Bulletin was published as guidance for
conformity to DEF STAN 05-33, AQAP 6 (formerly DEF STAN 05 26).
Note that Error Range 4 is open-ended and, as the permissible error increases, it becomes possible to use
Class B glassware throughout.
Table 2 Error ranges for multi-mark volumetric glassware
Error
Range
Permissible overall
error in analytical
procedure*
Maximum specified
tolerance for
volumetric glassware*
Glassware usable without prior calibration
A < 1% 0.2% Certified burettes
Class A, capacity at least 5 cm 3
Uncertified burettes
Class A, capacity at least 25 cm 3
B > 1% eg > 0.2% Certified graduated pipettes
Uncertified graduated pipettes
Class A, all capacities
Class B, all capacities
Certified graduated burettes
Uncertified graduated burettes
Class A, all capacities
Class B, all capacities
Being translated, please wait..