p/n 18603-001, Rev. C LTV
®
1200/1150 Ventilator Service Manual Page E-13
If the instrument accuracy is 2% of full scale and the instrument has a full scale of 500 ml,
the resulting accuracy is 500 ml x 2% = 10 ml.
Under these conditions, reduce the tolerance from ± 30 ml by the accuracy of the
instrument (10 ml) for a “guard-banded” tolerance of 300 ml ± 20 ml = 280 ml to 320 ml.
Flow rate measurements
10 Lpm
When measuring a flow rate of 10 Lpm with a tolerance of ± 1.5 Lpm, the minimum accuracy
level for instrumentation would be 1.5 Lpm / 4 = 0.375 Lpm.
If the instrument accuracy is 2% of reading, at 10 Lpm the resulting accuracy is 10 Lpm x
2% = 0.2 Lpm. The resulting accuracy is less than the minimum accuracy level (0.375 Lpm)
and is acceptable.
If the instrument accuracy is 2% of full scale and the instrument has a full scale of 25 Lpm,
the resulting accuracy is 25 Lpm x 2% = 0.5 Lpm.
Under these conditions, reduce the tolerance from ± 1.5 Lpm by the accuracy of the
instrument (0.5 Lpm) for a “guard-banded” tolerance of 10 Lpm ± 1.0 Lpm = 9.0 Lpm to
11.0 Lpm.
50 Lpm
When measuring a flow rate of 50 Lpm with a tolerance of ± 7.5 Lpm, the resulting minimum
accuracy level for instrumentation would be 7.5 Lpm / 4 = 1.875 Lpm.
If the instrument accuracy is 2% of reading, at 50 Lpm the resulting accuracy is 50 Lpm x
2% = 1.0 Lpm. The resulting accuracy is less than the minimum accuracy level (1.875 Lpm)
and is acceptable.
If the instrument accuracy is 2% of full scale and the instrument has a full scale of 100 Lpm,
the resulting accuracy is 100 Lpm x 2% = 2.0 Lpm.
Under these conditions, reduce the tolerance from ± 7.5 Lpm by the accuracy of the
instrument (2.0 Lpm) for a “guard-banded” tolerance of 50 Lpm ± 5.5 Lpm = 44.5 Lpm to
55.5 Lpm.
90 Lpm
When measuring a flow rate of 90 Lpm with a tolerance of ± 13.5 Lpm, the resulting
minimum accuracy level for instrumentation would be 13.5 Lpm / 4 = 3.375 Lpm.
If the instrument accuracy is 2% of reading, at 90 Lpm the resulting accuracy is 90 Lpm x
2% = 1.8 Lpm. The resulting accuracy is less than the minimum accuracy level (3.375 Lpm)
and is acceptable.
If the instrument accuracy is 2% of full scale, and the instrument has a full scale of 100 Lpm
the resulting accuracy is 100 Lpm x 2% = 2.0 Lpm. The resulting accuracy is less than the
minimum accuracy level (3.375 Lpm) and is acceptable.
Oxygen blending percentage measurements
30%
When measuring oxygen blending of 30% with a tolerance of ± 3%, the resulting minimum
accuracy level for instrumentation would be 3% / 4 = 0.75%.
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