16
Table 3-2. Combining Noise Sources
Difference Between
No. of dB to be Added to
Levels in dB
Higher Level
0
3.0
2
2.1
4
1.5
6
1.0
8
0.6
10
0.4
4.
OPERATING INSTRUCTIONS
This section contains the instructions required for the operation of the 884-2
Sound Level Meter. Follow these instructions carefully to obtain accurate and
useful data.
If noise levels exceed 115 dB(A) (SLOW response) immediate use of protective
ear muffs or plugs is required. According to the Occupational Safety and Health
Act of 1970, noise that measures above 115 dBA is automatically "too high" for
any length of exposure approximately over one second.
4.1
Precautions
a.
Read Section 3 before performing measurements. This section contains im-
portant information on terminology, standards, techniques, and precautions
pertinent to sound and noise measurements.
b.
Use the 890-2 Calibrator to check the calibration of the Sound Level Meter
periodically, especially if the Instrument has been subjected to severe me-
chanical shock or environmental extremes.
4.2
Operational Items And Features
All items and features used to operate the 884-2 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 In-
strument on and to select the desired measurement range.
The range is indicated by the arrowhead. With the range
switch 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 corresponds to
either 130, 120, 110, 100, 90, 80, 70, 60, or 50 dB as
determined by the position of the range switch. An indica-
tion other than zero (0) must be added to the range se-
lected to obtain final level indication. For example, if the
range switch is set to the 110 position, and the indication is
+5, the sound level is 115 dB.
2.
SLOW/FAST
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