Survey Meter vs. Personal Monitors

["Mercado, Don" <don.mercado@lmco.com>]

Happy new year, Radsafers!	

I am currently debating the wisdom of using personal alarming RF
monitors vs. a survey meter for measuring RF fields. The monitors have a
digital readout that can be compared to the IEEE RF standard, are
available now, seem to be more rugged than a survey instrument, requires
less training to use, and are MUCH cheaper. The survey instrument is a
more "standard" way of measuring RF fields, is more precise and less
directional, but is not currently available and costs big bucks. The
users have the monitors, are buying a survey instrument (but can't get
it for 3 months) and have asked to borrow my survey instrument in the
mean time. I'm reluctant to do that because they have a history of
breaking it and have a problem interpreting survey results. I can't be
there all the time to do RF surveys for them, so I have asked them to
use the personal monitors to do their own surveys. Unfortunately, the
users "trust" a survey meter more than the monitors, so they are
reluctant to do that. The monitors are set to alarm at 1 mW/cm2, so if
there was a leak (which there shouldn't be, all RF emissions are
supposed to be enclosed) the users would be warned, and 20 monitors
cover a wider area than one survey meter. Both the monitors and my
survey meter are under factory NIST traceable calibration. A monitor
"checker" has been ordered and should be on site now, so in case one is
dropped or is otherwise suspect, its function can be assessed. 

My question: Is there a reason the personal monitors should *not* be
used to survey RF fields? I mean, isn't that what they do? Have any of
you used them that way or encountered a problem with them? One
manufacturer of monitors that do not have digital readouts indicated
that they did that on purpose so that they wouldn't be used as survey
meters. I'm not sure why, other than to sell more of the expensive
survey meters. I'm inclined to use the monitors because I can't afford
the time necessary to stand around waiting to do an RF survey, can't
afford to keep paying for instrument repairs, can't find a good reason
not to, and they are nearly idiot proof. I'm not trying to quantify the
field, just determine if there is a problem or not.

What 'cha think? Any comments would be helpful. Thank you in advance.


Donald P. Mercado
Radiation Safety Officer
Lockheed Martin Missiles & Space
O/47-20, B/101
1111 Lockheed Martin Way
Sunnyvale, CA 94089
Ph. (408) 742-0759
Fx. (408) 742-0611
Email: Don.Mercado@lmco.com