Simpson 886-2, Operator'S Manual, Page: 17 / 24

17
Act of 1970, noise that measures above 115 dB(A) is automatically “too high” for
any length of exposure approximately over one second.
4.1 Precautions
Read Section 3 before performing measurements. This section contains impor-
tant information on terminology, standards, techniques, and precautions perti-
nent to sound and noise measurements.
Use the 890-2 Calibrator to check the calibration of the Sound Level Meter peri-
odically, especially if the Instrument has been subjected to severe mechanical
shock or environmental extremes.
4.2 Operational Items And Features
All items and features used to operate the 886-2 are described in Table 4-1 and
illustrated in Figure 4-1.
Table 4-1. Operational Items And Features
1. Range Switch: This eleven position rotary switch is used to
turn the Instrument on and to select the de-
sired measurement range. The range is indi-
cated by the arrowhead. When the range
switch is set to the “OSHA” position, the dB
level is read on the red arc displaying the
OSHA range. With the range switch set to
one of the other dB ranges, the black arc is
used. A zero (0) indication on the black arc
10
9
8
7
6
5
4
3
2
1
0
0
1 2 3 4 5 6 7 8 9 10
dB D IFFERENCE BETWEEN TOTAL NOISE &
BACK G ROUN D NOISE MEASUREMENTS
dB
CORRECTION
(T
O
BE
SUBTRA
CTE
D
FR
OM
TOT
A
L
NOISE)
Figure 3-4. Background Noise Correction