X-Message-Number: 3414 Date: Wed, 16 Nov 1994 22:15:31 -0500 From: "Keith F. Lynch" <> Subject: Re: SCI.CRYONICS: High Pressure LN boiloff Yes, you can reduce the storage temperature either by using liquid nitrogen under negative pressure or by using liquid helium. Both would be expensive. Liquid helium is extremely expensive, and has a higher boiloff rate (due mostly to the greater difference from room temperature). I've always heard that liquid nitrogen is about as expensive as milk, and liquid helium is about as expensive as fine brandy. But what would be the point in a lower temperature? Liquid nitrogen at normal pressure is more than cold enough to stop all chemistry. Lower temperatures merely make tissue cracking worse. In fact, one might want to do storage at a *higher* temperature than liquid nitrogen's usual boiling point, perhaps by using liquid nitrogen under pressure. This would reduce both cracking and boiloff rates. Of course this adds complexity, risk, and expense. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=3414