Date: Mon, 17 Aug 2009 16:47:30 -0400
Reply-To: "Curtis, Martha" <mcurtis**At_Symbol_Here**NFPA.ORG>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: "Curtis, Martha" <mcurtis**At_Symbol_Here**NFPA.ORG>
Subject: Re: Recirculating fume hoods
Comments: To: Paul Dover
Comments: cc: "Goyette, Joanne" ,
"Mucci, Patti"
In-Reply-To: A<89907EA1DCFB7548A431C13A270F9DD507F1D0D5**At_Symbol_Here**prk-exch-01.vcp.local>

Dear All,

=A0=A0=A0=A0 My name is Martha Curtis and I am the Staff Liaison to NFPA’s Committee on Laboratories Using Chemicals which is responsible for NFPA 45, Standard on Fire Protection for Laboratories Using Chemicals.  I have been a member of the American Chemical Society since my graduation from college.  I am also a member of the ACS Division of Chemical Health & Safety, AIChE Safety & Health Division, ASSE, SFPE, and NEC-SFPE, the national society for fire protection engineers and its local chapter in New England.

=A0=A0=A0=A0 The 2004 edition of NFPA 45 addresses this type of hood as follows:

8.3.1  Laboratory ventilation systems shall be designed to ensure that chemicals originating from the laboratory shall not be recirculated.

8.4.1*  Air exhausted from chemical fume hoods and other special local exhaust systems shall not be recirculated. (See also 8.3.1.)

A.8.4.1  Ductless chemical fume hoods that pass air from the hood interior through an absorption filter and then discharge the air into the laboratory are only applicable for use with nuisance vapors and dusts that do not present a fire or toxicity hazard.

=A0=A0=A0=A0 For your information, NFPA 45 is available by calling NFPA’s Customer Service Department, 1-800-344-3555 or 617-770-3000, Extension 8660, or by download from NFPA’s website at  You can also view (but cannot copy) the document by going to the following web page:


=A0=A0=A0=A0 Scroll down to and select the desired document.  Scroll to the bottom of the next screen and click on “Preview this document”.  Follow the instructions from that point on.  Because the “on-line” documents are located on an external server, expect system loading and response to take a minute or two.

=A0=A0=A0=A0 If you have questions about NFPA 45, you can direct your inquiry to nfpa45**At_Symbol_Here** and your inquiry will be forwarded to me here at NFPA.

=A0=A0=A0=A0 Thanks for your interest in using NFPA’s codes and standards. =A0I recognize that many states ask for compliance with NFPA 45.=A0 I am assigned as the resource for those who have questions that they want answered on the standard.

=A0 Regards,

=A0 Martha H. Curtis

Martha H. Curtis
Senior Chemical Specialist/Staff Liaison to NFPA 45 
1 Batterymarch Park
Quincy, MA  02169-7471
Phone: 617-984-7496
Fax: 617-984-7110
Email: mcurtis**At_Symbol_Here**


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IMPORTANT NOTICE: This correspondence is not a Formal Interpretation issued pursuant to NFPA regulations. Any opinion expressed is the personal opinion of the author, and does not necessarily represent the official position of the NFPA or its Technical Committees. In addition, this correspondence is neither intended, nor should be relied upon, to provide professional consultation or services.
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From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**] On Behalf Of Paul Dover
Sent: Thursday, August 13, 2009 1:50 AM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: [DCHAS-L] Recirculating fume hoods

Dear all,


Can I please get some opinions on use of recirculating fume hoods?

We are looking at their potential use, primarily in undergraduate teaching. I’m sure we have all experienced the ‘hurricane’ effect from too many fume hoods in use.

Also the attractiveness of portability, environmental friendliness etc. that ‘ductless’ fume hoods seem to offer.


Here is an extract from our Australian/New Zealand Standard on these things:

AS/NZS 2243.9:2009 10



The recirculating fume cabinet shall not be used in the following circumstances (see also

Clauses 6.2, and

(a) For work with organic solvents which are only physically absorbed on the absorber

and the solvents -

(i) have boiling points less than 75=B0C; and

(ii) are evaporated in quantities of more than 50 mL per day.

NOTE: Fume from these organic solvents can be insufficiently delayed on the filter unless

chemisorption takes place, i.e. a chemical reaction between the absorbent and the solvent


(b) Where more than 50 mL of corrosive liquids are involved in a reaction or process that

generates fumes.

(c) Where perchloric acid digestions are carried out.

(d) Where other acid digestions are carried out except where these are conducted in

closed systems.

(e) Where infectious organisms are handled (see AS/NZS 2647 and AS 2252).

(f) Where Category 1 and Category 2 carcinogens (see NOHSC 1008), except those

which are chemisorbed by the filter, are used.

(g) Where radioactive materials exceeding ten times the annual limit of intake for

inhalation* are used.

(h) Where temperature and humidity extremes can affect filter operation.

However I don’t need to tell you guys that standards are not law.


Thanks in advance, Paul


Paul Dover
Resources Manager
Medicinal Chemistry and Drug Action
Monash Institute of Pharmaceutical Sciences
Monash University (Parkville Campus)
381 Royal Parade, Parkville
Victoria, 3052. Australia

Phone: +61 3 9903 9551
Fax:   +61 3 9903 9143

Email: Paul.Dover**At_Symbol_Here**

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