V-22 Sealing Requirements for Liquid Volumetric Proving Standards
Measurement Canada
PDF Format
Date: 2002-02-28
Bulletin: V-22-E
Category: Volume
1. Scope
The purpose of this bulletin is to outline the sealing requirements
for liquid volumetric proving standards that are calibrated and
certified by Measurement Canada.
2. Background
In an effort to monitor the calibration of liquid volumetric proving
standards, and to ensure better metrological control, the following
sealing requirements will come into force the effective date of this
bulletin and will be applied upon the recalibration due date of the
proving standard.
3. Policy
3.1 Sealing Requirements
Measurement Canada will affix seals to the identified components of
the proving standard at the time of calibration (water draw). Since
seal integrity can deteriorate due to environmental conditions and
everyday use, new seals will be affixed at each subsequent
calibration. For all liquid volumetric proving standards the following
components must be sealed at the time of calibration so as to prevent
their adjustment and/or removal:
3.2 Pipe Provers
For pipe provers all signalling detector switches, which define the
calibrated volume, must be sealed.
3.3 Small Volume Provers
In addition to sealing of signalling switches the following
components must also be sealed on small volume provers:
-
signalling detector switch cover/tube/housing assembly, and,
-
any calibration access switche(s) on the controller.
3.4 Open Neck Volumetric Provers
For open neck volumetric provers the following components, if
applicable, must be sealed:
-
gauge plate
-
all flanged or connections which make up part of the calibrated
volume; displacers, valves, drop tubes, thermal well(s) and or
thermometers without wells.
3.5 Variations From The Sealing Requirements
Some provers are designed so that component parts need to be removed
for various reasons. For example:
-
some open neck volumetric provers have removable necks for
transportation purposes
-
sanitary provers have butterfly valves which come apart for easy
cleaning
-
large provers have access hatches for visual inspections etc.
These provers in general are required to meet the same requirements as
those for open neck provers with the exception of components which may
need to be removed for sanitary, transportation, and/or inspection
purposes. These unique components that make up part of the calibrated
volume do not need to be sealed but each must be uniquely identified.
In addition to the markings, Measurement Canada will affix inspection
markings (plates) to the components to ensure inspection traceability.
This approach allows for the removal of components for the reasons
mentioned and ensures the proper components are used with the
appropriate standard.
4. Documentation
A valid Measurement Canada inspection certificate must accompany the
volumetric standard at all times if it is intended to be used by
Measurement Canada inspectors for inspection purposes. The certificate
shall identify the reference conditions of the calibration, the
essential construction data for the prover, and the number and
location of all inspection seals (including non-sealed component list
if applicable).
5. Missing Seals
If it is determined during an inspection that inspection seal(s) are
missing and/or an improper component is being used, the Measurement
Canada inspector will either continue on with the inspection holding
back the inspection certificate or discontinue the inspection. In
either case a confirmation water draw is required to ensure that the
certified base volume has not changed. If such an event should occur,
Measurement Canada will notify the owner of the standard, owner of the
measurement device and all other Measurement Canada offices of the
missing seals and the requirement for a confirmation water draw.
6. Breaking Seals
Should the owner of a standard wish to break seal(s) and/or
encounters a broken seal, a report must be submitted to the nearest
Measurement Canada office within 5 days of the removal or discovery of
the broken seal(s). The regional Measurement Canada Volumetric
Specialist should be notified of such an occurrence. Where Measurement
Canada has witnessed the breaking of a seal(s) and is confident that
the base volume of the prover has not been altered and the calibration
has not expired, may affix a new seal(s) without requiring a
confirmation water draw.
7. Replacing Switches
If the owner of a standard wishes to demonstrate that the removal and
replacement of switches does not affect the calibration of their
standard they can do so at the time of calibration. Results of any
additional testing will be documented on the inspection certificate.
This additional testing may allow for the replacing of switches during
a calibration cycle without requiring a confirmation water draw.
However, all of the sealing, documentation and reporting requirements
remain applicable.
8. Additional Information
For additional information regarding this bulletin, please contact
the Program Officer responsible for volumetric measurement. Further
information regarding Measurement Canada can be found on our web site.
Dennis Beattie CET
A/Program Officer, Volumetric Measurement
Program Development
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