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Re: rack power question
forwarded with permission. > From: "Bob Bradlee" <[email protected]> > To: "Paul Vixie" <[email protected]> > Date: Tue, 25 Mar 2008 11:16:17 -0400 > X-Mailer: PMMail 2000 Professional (2.20.2717) For Windows 2000 (5.1.2600;2) > Subject: Re: rack power question > > On 25 Mar 2008 06:17:15 +0000, Paul Vixie wrote: > > >this has been, to me, one of the most fascinating nanog threads in years. > > >at the moment my own datacenter problem is filtration. isc lives in a > >place where outside air is quite cool enough for server inlet seven or more > >months out of the year. we've also got quite high ceilings. a 2HP roof > >fan will .... > > Point taken, and I agree ... > > May I suggest we, make that the collective we, take all that extra floor > space that we don't have power for anywaydue to all the new blades servers > that need the cooling and put it to good use as a dust or (not so clean) > clean room to lower your cooling and cleaning costs. > > I worked on a project many years ago where "they" had built a big dust > collection room as an air scrubber for the computer room and some labs. > > Outside air and inside return air was brought in and mixed to an optimun > temp for the season at one end of a very long, very tall, very large, not so > clean, room sized dust collector they called the "clean room". On the far > wall was an array of low cost filters that fed the HVAC cold air return > path. > > Because the room was very large with a small inlet and a huge filtered > outlet wall. The air in the room stayed at a low pressure and was slowly > exhausted from the area at a very slow surface velocity. The vast majority > of the dust and just about all of the grit just fell out of the air onto the > floor where it could be cleaned up with a big shopvac or a snow shovel if I > had my way :-). > > Because most of the particulate matter hit the floor before it got to the > filters, the filter wall lasted many months vs the previous few weeks > between cleaning before the dust room was built. The "normal" filters in the > HVAC system had quality HEPA filters and rarely needed to be changed because > the air was being so well precleaned in the (not so) clean room long before > it ever got to the HVAC system. > > I was told me that what I was looking at was the second version, about twice > the cubic feet as the origional halway they first used. The filters now > lasted almost twice as long and they were moving much more air. > > The dust room I saw was very tall, I think 10 or 12 foot to the roof, it was > also very long over 30+ feet as I remember, but was limited to about 8 or 10 > feet wide (for other reasons). The filters used on the back wall were > designed to be used in the back wall of an auto paint booth and were low > cost and could be washed. Now that I think about it I expect the width was > determined by the size of the filter rack. I was told that before > remodeling, version one started as a long wide hallway that was off sealed > off and used as a big cold air return, using the old double doors on one end > as the "filter rack". I worked so well that when they remodeled, the hall > was widened and was opened up so that the cubic area of the low pressure > area could be maximized. > > What made it work was, the fact that small inlet vs a large outlet creates > low pressure in a large area. A long run of slow moving air in low pressure > will drop its dust and grit along the way, long before it gets a chance to > plugged up the filters. Think of it as a room size shopvac or a big Dysen > vacuum cleaner. :) > > I was told by the operator it worked better than he thought it would, and if > he was to build it again he would have wasted more floor space and made it > wider but could not justify the Sqfoot cost at that time. If he was > designing from scrach at todays energy costs, it would feed the whole > building not just the computer room and labs. > > He pointed out that while increased room height increased the cubic feet and > reduced pressure allowing more particulate to fall per SQfoot, increasing > the floor area was the same as increasing the effective filter area while > also reducing the static pressure in the room, win win. > > Bottom line, the bigger the better, make a dust room big enough you might > not need filters :-). > > Got a back room, you can seal up, or some unimproved space you can convert > into a home built open air scrubber ? > > I have seen it work ..... and it has been working for many years .... > Sorry I just can't tell you where, or I would have to kill you :-) > > Bob Bradlee > 614-xxx-xxxx > > PS. As I can not post to this list from this address, feel free to reply on > list if you think others might like to chime in.