This is a message from the Museumpests List. To post to this list send it as an email to pestlist@museumpests.net To unsubscribe please look at the footer of this email. ----------------------------------------------------------- Re: Air movement in elevator shafts and pesticides
The movement of elevator cars inside elevator shafts does not typically generate large pressure changes. This is called the *piston effect. *The effect is essentially proportional to the speed of the movement and inversely proportional to the number of cars in the shaft (bigger shafts are less tight and there is a lot of air leakage at the doors). For example, with a single elevator car traveling at a velocity of 400 ft. per minute (fpm), there is a pressure differential of 0.08 inches of H2O. For a double-car shaft, it is only 0.02 inches of H20. The *piston effect* only occurs during car movement. The *stack *or *chimney effect*, however, can produce larger pressure differentials that generate air movement to balance pressures. The natural buoyancy of warm air will cause it to rise, creating a negative pressure in the lower areas and a greater pressure higher up. This is enhanced in heated buildings in the winter and partially reduced in air-conditioned buildings in the summer (the *reverse stack effect*). The *stack effect* is driven by building geometry and the laws of physics and *it never turns off. * The strength of the *stack effect* is influenced by numerous factor related to building height (the height of the stack), interior and exterior temperatures, location and types of openings and building envelope tightness (air leakage), exterior wind velocity and direction, whether and how the top of the elevator shaft is ventilated to the exterior (total area, automatically dampered), etc. For example, the stack-effect pressure differentials published by ASHRAE range from 0.07 inches of H2O at 30 ft. to 0.7 inches of H2O at 300 ft. Additionally, a 15 mph wind perpendicular to a building can result in a wind-effect pressure differential from the windward to leeward side of 0.12 inches of H2O. The *stack effect* can have significant unintended consequences and can lead to the movement of considerable volumes of air, moisture, smells, mold spores, dust, etc. up the shaft and through other parts of the building leading to the shaft. Interior conditions can be degraded with unexpected drafts and surprising temperature and humidity conditions. Importantly, condensation, with associated damage and biological growth, can occur in unexpected locations due to such air movement. Considerable amounts of expensive heated air (energy) are lost up the stack this way as well, as anyone who leaves their fireplace chimney flue open knows. The International Building Code and local building and fire codes have guidance on elevator shaft ventilation requirements. Some controversy remains about the best ways to handle fire and smoke in elevator shafts. Such air movement pathways may also provide access for vermin. The solutions include a deeper understanding of building science than is prevalent, great attention to detail during the design phase, and continuous supervision during the construction phase of a building. Some ventilation is obviously essential. However it needs to be properly understood and controlled. The importance of removing organic debris and potential bio growth habitat during construction, during renovations, during routine maintenance (which almost always needs to be better defined and more extensive), and during operations cannot be overstressed. Contractors must be told that such debris cannot be left behind, particularly in crawl spaces, under slabs, in attics, etc. and especially in the various interstices of a building where it cannot be seen and or easily removed. In addition to encouraging damaging biological growth, such debris can be a real fire hazard. William C. S. Remsen, RA Chief Preservation Architect International Preservation Associates, Inc. 85 Strawberry Hill Street Dover, MA 02030 508.561.1740 wremsen...@gmail.com On Thu, Nov 3, 2011 at 11:17 AM, Mary Baughman <m.c.boff...@mail.utexas.edu>wrote: > This is a message from the Museumpests List. > To post to this list send it as an email to pestlist@museumpests.net > To unsubscribe please look at the footer of this email. > ----------------------------------------------------------- > ** > Hi - > > I haven't researched this concern; > anecdotal evidence is all I have to back up a suspicion: > I wonder if elevators function like a bellows - pushing air up and down in > the building. > Is my concern unfounded? > If there is truth to the bellows notion, I would prefer that any pesticide > used in an elevator shaft be in a bait form that could not be pumped up and > down - and out - as the elevator moves. > > Mary Baughman > > This is a message from the Museumpests List. > To post to this list send it as an email to pestlist@museumpests.net > To unsubscribe please look at the footer of this email. > ----------------------------------------------------------- > > Denise - > > > > I think Gentrol would be a waste of chemical. Gentrol holds larvae in the > larval state; it usually does not prevent eggs from hatching. The Alpine > Dust would be a good choice as long as the elevator pit remains dry. > > > > Thomas A. Parker, PhD > > Pest Control Services, Inc. > > -----Original Message----- > From: Denise Migdail <dmigd...@asianart.org> > To: pestlist <pestlist@museumpests.net> > Sent: Wed, Nov 2, 2011 3:12 pm > Subject: [pestlist] Webbing Clothes Moths and Gentrol? > > This is a message from the Museumpests List. > To post to this list send it as an email to pestlist@museumpests.net > To unsubscribe please look at the footer of this email. > ----------------------------------------------------------- > After tracking and mapping webbing clothes moths for several months, we > have pinpointed our elevator shaft as a primary source. It housed a > gradual build up of debris from eight years of service, which when > inspected did contain larvae. We are now looking at having the elevator > shaft floor thoroughly cleaned and sprayed. Our facilities provider has > suggested using Gentrol, but we have only found it referenced with regards > to beetles in the literature. Any comments on the efficacy of Gentrol for > webbing clothes moths would be appreciated. We are also considering using > an insecticide/desiccant combination - such as PyGanic, or Alpine Dust (two > suggested by our facility providers). > > Denise Migdail > Textile Conservator > Asian Art Museum > 200 Larkin Street > San Francisco, CA 94102 > > ---------------------------------------------------------------------- > To send an email to the list, send your msg to pestlist@museumpests.Net > > To unsubscribe from this list send an email to pestlist@museumpests.netand in > the subject put: > "unsubscribe" - no quotes please. > > You are receiving the Pestlist emails in standard mode. > To change to the DIGEST mode send an > email to imail...@museumpests.net with this command in the body: > > set mode digest pestlist > > Any problems email l...@collectionpests.com or l...@zaks.com > > > ---------------------------------------------------------------------- > To send an email to the list, send your msg to pestlist@museumpests.Net > > To unsubscribe from this list send an email to pestlist@museumpests.netand in > the subject put: > "unsubscribe" - no quotes please. > > You are receiving the Pestlist emails in standard mode. > To change to the DIGEST mode send an > email to imail...@museumpests.net with this command in the body: > > set mode digest pestlist > > Any problems email l...@collectionpests.com or l...@zaks.com > > > > ---------------------------------------------------------------------- > To send an email to the list, send your msg to pestlist@museumpests.Net > > To unsubscribe from this list send an email to pestlist@museumpests.netand in > the subject put: > "unsubscribe" - no quotes please. > > You are receiving the Pestlist emails in standard mode. > To change to the DIGEST mode send an > email to imail...@museumpests.net with this command in the body: > > set mode digest pestlist > > Any problems email l...@collectionpests.com or l...@zaks.com > ---------------------------------------------------------------------- To send an email to the list, send your msg to pestlist@museumpests.Net To unsubscribe from this list send an email to pestlist@museumpests.net and in the subject put: "unsubscribe" - no quotes please. You are receiving the Pestlist emails in standard mode. To change to the DIGEST mode send an email to imail...@museumpests.net with this command in the body: set mode digest pestlist Any problems email l...@collectionpests.com or l...@zaks.com
