VIacoustics ACCULAB RSS-101 - RPM and Environmental Corrections

2021 RSS Manual all models.doc. Page 13 // 02/12/21
CORRECTIONS
Nominal values are corrected for Reference Meteorological Conditions of 23.0 C, 101.325 kPa and 50%
RH and have been adjusted for air absorption at the time of the calibration per ISO 3745/ANSI S12.55
Equation 19 and ISO 9613-1:1993. Actual RSS sound power level emitted at a test site will depend on
temperature, barometric pressure, and humidity at the test site. Adjustments to the calibrated sound power
can be calculated as described in ISO 3745 Equation 16 and ISO 9613-1.
The table below may be used to correct for variance between RPM read from a tachometer or
strobe and the RPM stated in calibration documentation. Or, if available, a variable transformer
may be used adjust the input AC voltage as to obtain the RPM stated in calibration
documentation.
Frequency Range:
12 – 40 Hz
50 – 160 Hz
200 – 10,000 Hz
test RPM - cal RPM
Correction, dB
+30
+o.1
+o.2
+o.3
+20
+o.1
+o.2
+o.2
+10
-0-
+o.1
+o.1
Cal RPM ( )
-0-
-0-
-0-
-10
-0-
-o.1
-o.1
-20
-o.1
-o.2
-o.2
-30
-o.1
-o.2
-o.3
1. Measure the RPM with an optical tachometer or strobe
2. If the observed RPM that occurred during your test departed more than 10 RPM from the value at
calibration, then correct the sound power values according to the following table. The emitted sound
power of the RSS unit increases at higher fan RPM and decreases at lower fan RPM.