UV lamps and exposure criteria (fwd)

[steven t hand <hand@wam.umd.edu>]

Good Afternoon:

I somehow was bumped off of the listserver and have no gotten back
on.  I am resending this so there may be some extra stuff at the top
of the message.  Please excuse this.  Thank you for your help on this
issue.


steve at umcp
hand@wam.umd.edu
fax: 301-314-9467
---------- Forwarded message ----------
Date: Fri, 21 Mar 1997 14:51:00 -0500 (EST)
From: steven t hand <hand@wam.umd.edu>
To: radsafe@romulus.ehs.uiuc.edu
Subject: UV lamps and exposure criteria

	

I have an experiment involving UV lamps and plants.  I am calculating	
the irradiance the radiant exposure and trying to deterine allowable
stay times without eye protection.  Please contact me to let me know
if my calculations are correct, or where they  are wrong.  Thank you
very much.

steve at umcp
hand@wam.umd.edu

Wavelength is 313 nm (UV-B range)
Equation for irradiance from lamp is E=P/2(Pi)rL, where :

P= 40 Watts/bulb x 12 bulbs
Pi= 3.14
r= 1 meter (distance from bulb to researcher)
L= bulb length = 1.22 meters

E = 480 Watts / 2*(3.14)*(1m)*(1.22m) = 63 W/m^2

H the radiant exposure is for an 8 hour exposure 63W/m^2 * 3600 seconds ?

H = 2.27 x E+5 J/m^2 ?


or

Do I calculate the effective irradiance = 63W/m^2 * SRE * wavelength

E(eff) = 63*(.006)*(313) = 118 W/m^2

Limiting value for 8 hours from ACGIH TLV is 5000 J/m^2.  Does this imply	

allowed time t = H/E(eff) = 5000 J/m^2 / 118 W/m^2 = 42 seconds ?


I am confused about which values to plug in and use, as you can see from
the above calculations.



If it is easier to fax me something on this please feel free to do so at
(301)-314-9467.  Also I can be reached at (301)-405-3985 at work.

Thanks again.


ps. standard uvex goggles were purchased at 3.50 for the researchers to
wear when they were in the room with the lamps.