National Institutes of Health 
Dr. Fredrickson 
9/21/78 
Page 5 
F. The Laboratory Safety Monograph does not contain a Leak 
Tightness test for Class II Type B cabinets. In order to perform 
the HEPA filter leak test in this cabinet, the bottom access 
panels must be removed. If they are not reinstalled leak tight, 
unfiltered ambient air will be drawn in through the leaks and 
will reach the work surface of the cabinet without filtration. 
Therefore a leak test is required. The procedure of pressurizing 
and soap bubble testing is sufficient. 
G. We would like to see a recommendation for the use of 
a separate centrifuge room or cubicle added to section IV-A of 
the Laboratory Safety Monograph. The room should be designed 
so that the ventilation system can be sealed off from the rest of 
the P3 facility so that the room can be decontaminated with 
paraformaldehyde without Shutting down the rest of the facility 
or losing the inward airflow to the facility. Rotor failures in 
ultracentrifuges are common and provision should be made for 
containing the spill and decontaminating the area when a failure 
occurs. 
H. Paragraphs III-B-7-b- (3) and III-B-7-b- (5) - (a) of the 
Laboratory Safety Monographs are written around a particular 
Laskin nozzle containing 2 shearing jets (these numbers are also 
used in NIH specifications and NSF Std 49) . The original work on 
DOP generators used a 4 jet nozzle (Echols, W.H. and J. A. Young, 
"Studies of Portable Air-Operated Aerosol Generators", NRL Report 
5929, U.S. Naval Research Laboratory, Washington, D.C. July 26, 
1963) . This nozzle is currently sold by one manufacturer. It 
requires 2 scfm of air and produces twice the smoke that a 2 jet 
nozzle produces. These paragraphs should be revised to permit 
the use of this nozzle on a basis of 1 per 1,000 cfm. This 
recommendation is also included as part of the comments below. 
I. The integrity of the containment systems depends heavily 
on the adequacy of the certification procedures used, and 
particularly the equipment used to leak test HEPA filters and 
measure airflow. The Laboratory Safety Monograph does not 
adequately define equipment and calibration requirements. En- 
closed is a paper "Testing of Laminar Flow Equipment" Journal 
of the Parenteral Drug Association 32:174-181 (July-Aug) 1978 
which discusses some of the problems involved in making sure 
test equipment is correct for certification. We suggest that the 
paper be included as a reference in section VI-F of the Laboratory 
Safety Monograph, and that the data of figures 1,2,4 and 11 be 
added to appropriate parts of section III-B of the Monograph. 
When inserting this data in the monograph, the sampling probe 
[A-222] 
