ETS-Lindgren HI-3603 VLF Survey Meter - Manual (Page 36)

HI-3603 VDT/VLF Survey Meter
© ETS-Lindgren, August, 2005
Revision E, Part # H-600042
36
USING THE MAX HOLD FEATURE
In some instances it may be useful to perform area surveys for
identifying locations of elevated exposure and determining the
maximum field strength in a given area (for example an entire
office, series of offices or region within a single office). Such area
surveys are simply accomplished by making use of the MAX
HOLD feature on the HI-3603. First, locate an area at least 3-4
meters away from any VDT's. Next, press the MAX HOLD
keypad and release. This insures that the MAX HOLD memory
has been cleared. Now, slowly walk through the study area,
moving the sensor paddle about so that the space under
consideration has been adequately sampled, returning to the
origination point. Now depress the MAX HOLD keypad once
more and while keeping the keypad depressed, record the
maximum value of field strength. Each time the MAX HOLD
keypad is depressed the MAX HOLD memory is cleared. Be sure
to record the maximum indicated value before releasing the
keypad.
GUIDELINES FOR RF EXPOSURE
To provide a means for judging the significance of measured
electromagnetic field emissions found near VDT's, the scientific
literature can be examined for information on suggested
exposure or emission limits. The exposure standards reviewed at
the time of this manual's preparation apply to humans for the
purpose of establishing safe working or living environments
where electromagnetic fields exist. The exposure limits compiled
in this manual are those found that correspond most closely to
the predominant frequency range of VDT's. In some cases, the
standards apply to occupational exposure environments and in
other cases, to the general living environment; often standards
for this latter case are referred to as general population or public
exposure limits.
Traditional approaches to radiation protection, principally derived
from ionizing radiation protection practices, usually differentiate
between occupational and public exposure. Generally,
occupational exposure limits are higher, i.e., more permissive,
than public limits. This is because of the greater uncertainties
associated with the general public; in the work place, employees