
Reference Manual
00821-0100-4810, Rev AA
March 2004
3-2
405 and 1595
GRAVIMETRIC
PROCEDURE
Piping is selected to match the inside diameter of the flowmeter under test.
Carbon steel piping is normally used for these tests. Gaskets between pipe
flanges are carefully installed and checked to ensure that they not interfere
with the flow. Proper alignment of the flowmeter with the piping is maintained.
After all piping is secured with bolts, couplings, or clamps. Water is gradually
introduced into the line. Flows are set to purge air from the system and to
bring the flowmeter to steady-state temperature. After operating the system
for a period of time, air is purged from all instrumentation lines, instruments,
and the flowmeter. After air purging, all instrumentation is checked for
zero-flow indication.
The flow rate is set by adjusting the control valve at the end of the test line to
a desired flow. This flow is allowed to stabilize and reach steady-state
condition. This condition is achieved when the average flow-meter readout is
constant with time. At this point, the calibration run begins.
A calibration run consists of simultaneously recording the flowmeter output
while the weighing tank is filled and the filling process is timed. Electronic
timers are activated and deactivated by electric eyes on the switch way.
Outputs are recorded at 1 Hz during this time. The duration of the run is
typically between 50 and 100 seconds
In addition to recording weight and time, the water temperature, air
temperature at the weigh tank, and air temperature adjacent to the readout
are recorded. Barometric pressure is also recorded at the start and at the end
of the test.
After a run is completed, the control valve is reset to another flow rate and the
process is repeated. Runs are normally conducted at 10 different flow rates,
approximately equally spaced from the maximum to the minimum flow rates.
In some cases, the maximum flow obtainable by the test facility determines
the upper flow limit of the test.
FLOW TESTS A summary of the tests provided on the following pages:
Run to Run Repeatability Meter section was assembled, tested, disassembled, re-assembled and
re-tested.
• 405P, Water, 06442, 1.5-in., 0.40 beta (see page 3-4)
• 405P, Water, 13443, 2-in., 0.65 beta (see page 3-6)
• 405P, Water, 26171, 4-in., 0.65 beta (see page 3-8)
• 405C, Water, 08261, 2-in., 0.40 beta (see page 3-10)
• 405C, Water, 12402, 2-in., 0.60 beta (see page 3-12)
• 405C, Water, 16261, 4-in., 0.40 beta (see page 3-14)
• 405C, Water, 24061, 4-in., 0.60 beta (see page 3-16)
• 1595, Water, AT24261, 6-in., 0.40 beta (see page 3-18)
• 1595, Water, AT39422, 6-in., 0.65 beta (see page 3-20)
• 1595, Water, AT48003, 12-in., 0.40 beta (see page 3-22)