Filter
Top Products
Installation and Configuration Manual 43
Maintenance and Fault Finding
SpecificationMaintenance and Fault Finding
5.4.7 Leak testing the 3098 specific gravity meter
Leaks incurred during servicing can be categorized under two main headings:
• Reference chamber leaks
a. Charge the reference chamber to 6.5 bar G using any clean dry gas.
b. Pass a gas of constant specific gravity (for example, nitrogen) through the instrument, and
when stabilized, record the time period.
c. Repeat operation twice every day for three or four days, ensuring that there are no large
temperature changes at each reading. A downward drift in the time period indicates a leak.
Note: Further tests can be done in order to define the nature of the leak. These procedures are laid out
in Section 5.3.
• Gas Path to Atmosphere Leaks
a. Apply any clean dry gas at a pressure of 6.5 bar G to the meter.
b. Apply a soap solution, or 'Snoop', to all disturbed areas of the meter and observe for any
bubble formation.
c. Seal as required and on completion of a satisfactory leak test, vent the meter to
atmosphere.
5.4.8 Post-maintenance tests
A density measurement check on ambient air will verify that the vibrating cylinder is functioning
correctly. A full calibration followed by a calibration check preferably using two suitable calibration
gases, as previously described, will be necessary to prove the system. This check, when carried out
over a period of time acts as a leak detection test.
5.4.9 Worked example of calibration certificate
This example relies on the following criteria being assumed:
The calibration gases in their pure state are passed through the meter and their respective periodic
times measured. From this information, the coefficients are derived.
Specific gravity 0.5–0.7
Gas line pressure 15 Bar
Reference chamber pressure 7 Bar G
Calibration gases CH
4
and N
2
SG values 0.5549 and 0.96715