Retrotec DM32 - Manual (Page 85)

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©Retrotec Inc. 2014
Table 12: Errors in Estimated Flow at 50 Pa if gauge "n"= 0.65 differs from actual n
Actual Flow Exponent (n) of Enclosure
0.50 0.55 0.60 0.65 0.70 0.75
Achieved
Pressure (Pa)
10 -21.4% -14.9% -7.7% 0.0% 8.4% 17.5%
15 -16.5% -11.3% -5.8% 0.0% 6.2% 12.8%
20 -12.8% -8.8% -4.5% 0.0% 4.7% 9.6%
25 -9.9% -6.7% -3.4% 0.0% 3.5% 7.2%
30 -7.4% -5.0% -2.5% 0.0% 2.6% 5.2%
35 -5.2% -3.5% -1.8% 0.0% 1.8% 3.6%
40 -3.3% -2.2% -1.1% 0.0% 1.1% 2.3%
45 -1.6% -1.0% -0.5% 0.0% 0.5% 1.1%
50 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%
55 1.4% 1.0% 0.5% 0.0% -0.5% -0.9%
60 2.8% 1.8% 0.9% 0.0% -0.9% -1.8%
65 4.0% 2.7% 1.3% 0.0% -1.3% -2.6%
70 5.2% 3.4% 1.7% 0.0% -1.7% -3.3%
If the “n” value on the gauge is set to 0.60 and the enclosure n is different, an error, as shown in Table 13
will result if the [@ Pressure] function is used at the Achieved Pressure to estimate result at 50 Pa.
Table 13: Errors in Estimated Flow at 50 Pa if gauge "n" = 0.60 differs from actual n
Actual Flow Exponent (n) of Enclosure
0.50 0.55 0.60 0.65 0.70 0.75
Achieved
Pressure (Pa)
10 -14.9% -7.7% 0.0% 8.4% 17.5% 27.3%
15 -11.3% -5.8% 0.0% 6.2% 12.8% 19.8%
20 -8.8% -4.5% 0.0% 4.7% 9.6% 14.7%
25 -6.7% -3.4% 0.0% 3.5% 7.2% 11.0%
30 -5.0% -2.5% 0.0% 2.6% 5.2% 8.0%
35 -3.5% -1.8% 0.0% 1.8% 3.6% 5.5%
40 -2.2% -1.1% 0.0% 1.1% 2.3% 3.4%
45 -1.0% -0.5% 0.0% 0.5% 1.1% 1.6%
50 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%
55 1.0% 0.5% 0.0% -0.5% -0.9% -1.4%
60 1.8% 0.9% 0.0% -0.9% -1.8% -2.7%
65 2.7% 1.3% 0.0% -1.3% -2.6% -3.9%
70 3.4% 1.7% 0.0% -1.7% -3.3% -4.9%
Achieved pressure is the actual maximum pressure achieved in the enclosure during the test.
𝐸𝑟𝑟𝑜𝑟 = (
𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑜𝑓 𝐼𝑛𝑡𝑒𝑟𝑒𝑠𝑡
𝐴𝑐ℎ𝑖𝑒𝑣𝑒𝑑 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒
)
(𝐴𝑐𝑡𝑢𝑎𝑙 𝑛−𝐴𝑠𝑠𝑢𝑚𝑒𝑑 𝑛)