Dear Sergei, Sorry to hear that you have lost samples due to the dry shipper warming up.
In all our shipments to/from various synchrotrons we've only had two arrive 'warm', shipping to/from London. One was returning from the Swiss Light Source to London and where the vacuum failed during transit, so it arrived warm. We disposed of this dry shipper rather than trying to re-evacuate it. The second was en-route to Diamond Light Source where the courier had the box over the weekend at their intermediate storage at Heathrow. We assumed that it was laid on its side from Friday - Monday as the vacuum was still fine and the shipper retained nitrogen and is still in use, but the samples for this shipment were lost. These failed shipments have been over a period of many years with many shipments per year (>50 if counting out and back separately) to various sites around Europe and a handful to the USA. We've had another shipper where the vacuum failed overnight whilst it was still in the lab and full of liquid nitrogen. Fortunately, I managed to rescue the samples into a second shipper with no apparent issue. The sign here was the outside being covered with condensation and being cold to the touch. We generally use either the square plastic shipping boxes or the smaller metallic ones, but we do have one dome shaped one. Nearly all our shippers are CXR100, as it is easier to load Unipucks, and we try and test the retention time at least one or twice a year. Couriers have been a combination of DHL to Diamond in the UK and Fedex to/from Europe. In the past, we've only used more expensive specialist couriers for same day shipments. It might be worth checking that the local courier is keeping the shipper upright for any overnight storage. Following the issue above, we generally ship early in the week to minimise time where the dewars being stored over the weekend. We have had deliveries of equipment with tilt indicators, and they might act as a deterrent as well. Hope this is of help. Andy Purkiss Crystallography Lab Manager. ________________________________ From: CCP4 bulletin board <[email protected]> on behalf of Sergei Strelkov <[email protected]> Sent: 22 October 2026 14:42 To: [email protected] <[email protected]> Subject: Re: [ccp4bb] About dry dewars You don't often get email from [email protected]. Learn why this is important<https://aka.ms/LearnAboutSenderIdentification> External Sender: Use caution. Dear Community, I wanted to pick up this thread as we recently had two instances of our crystals arriving warm to the synchrotron. Our shipments are within continental Europe to the ESRF and take under two days if we are lucky, but often longer. We ship dewars in standard shipping cases. We did the following tests with our not-that-new CX100 and also CXR100 (a wider-neck version of CX100). The dewars were saturated with LN2, with cold racks/pucks in place. When stored in the normal upright position, both our dewars stayed cold for 10 days or more. However, when we laid them on the side, the hold time was only about two days for CX100 and less than 24h in some tests with CXR100! Our conclusion is that the problem lays in the courier not storing the dewars properly in the upright position. As we are getting a bit desperate, I would appreciate your opinions/advice. Should we get a special dome-shaped enclosure like Upright Shipping case for CX100 and CXR100, Dry Shippers - Jena Bioscience<https://www.jenabioscience.com/crystallography-cryo-em/specimen-storage-shipping/dry-shippers/x-4lsc-upright-shipping-case-for-cx100-and-cxr100> ? Should we attach a tilt indicator to our existing enclosure? (In addition to the standard 'keep upright' sign which is there already of course) Should we use a dedicated expensive courier for scientific samples? Thank you! Sergei Prof. Sergei V. Strelkov Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven O&N2, Campus Gasthuisberg, Herestraat 49 bus 822, 3000 Leuven, Belgium Phone: +32 486 29 41 32 (mobile) Lab pages: https://gbiomed.kuleuven.be/english/research/50000715/50000719/ ________________________________ From: CCP4 bulletin board <[email protected]> on behalf of Mitchell D. Miller <[email protected]> Sent: Friday, October 18, 2024 16:48 To: [email protected] <[email protected]> Subject: Re: [ccp4bb] About dry dewars Another good way to test the dry shipping dewar is to its dry/empty weight. If you don't know your "as new" mass, you can weigh it, then purge with dry air/nitrogen for 24 hours and check the weight again, if it is unchanged, then you can use that as your dry/empty weight. Next you can charge the shipping dewar according to the manufacturer's specs. Pour out the excess LN2. Then weigh the unit. This will tell you the capacity of LN2 retained in the absorbent material. (You can compare this to the manufactures specs). Then you can leave the unit for 24 hours and then weigh it again. From the difference of the mass, you can calculate the nominal evaporation rate. E.g. how much LN2 is lost each day. Then divide the mass of the retained LN2 by this evaporation rate to find the number of days of holding time. For a CX100 dewar, the absorbent material should hold 4.4 L of LN2 which is 3.6 kg and should have a holding time of ~21 days when new. For the MVE SC4/2 it holds 3.8 L (3.1 kg) with an expected holding time of 14 days when new. (note 1 l LN2 = 0.808 kg) A good check you can do each time before sending out your samples is to fill the shipper the day before (you can leave excess liquid in the shipper). After you have fully charged it and it is cold (an hour or so) record the weight. Then take another measurement 12-24 hrs later and calculate your evaporation rate to confirm it is close to what you expect. There are some nice guides at https://smb.slac.stanford.edu/facilities/hardware/cryotools/shipping-dewar-testing.html https://www.diamond.ac.uk/Instruments/Mx/Common/Common-Manual/Shipping-Samples/Care-of-dry-shippers.html I know that the LS-CAT group at the APS has the correct vacuum operator to pump out the CX100 dewars. If that is the same one you have, they might be able to tell you the source/supplier for it. I had looked for the operator for the MVE SC4/2 type dewars, but did not find confirmation on the correct thread pitch. When I contacted tech support at the vendor we purchased the dewar from, they contacted the manufacture and were told that they don't consider it user serviceable and would not relay the diameter and thread pitches. Here is a general video on the evacuation process -- https://www.youtube.com/watch?v=hnPZrGdcTSs Here is a DIY solution --- http://www.nuclearphysicslab.com/npl/npl-home/spectroscopy/software_and_hardware/refurbishment-of-ln2-dewars/ Regards, Mitch Quoting Artem Evdokimov <[email protected]>: > Cheapest possible system to check dry shipper would be a wooden stick > lowered into the shipper then taken out and exposed to moist air. > Condensation would indicate a cold zone... > > Second cheapest option is a red LED on a pair of long thin wires. If it > changes to green as it dips into the dewar, again- it is cold in there. The > change will be partial depending on the actual temperature. Please note > this only works with inorganic LEDs. > > If you crave precision and actual numbers, then you should invest a dollar > or two in a type K thermocouple. It is good down to -200 C which is lower > than LN2 temperature. These are on ebay and Amazon for a few bucks. A few > more bucks will get you a thermometer body with the right connector, or you > can use a multimeter and recall that the voltage change should be about 41 > microcolts per degree C. You can calibrate your system in LN2 and ice or > boiling water to get the correct thermal coefficient and offset. Just don't > forget to use the same connection and instrument all the time since the > reference junction will change if you change the setup. > > As to re-evacuating the dewar - this varies depending on how your > particular device is constructed. Some have a 'nipple' style valve, others > have a needle style valve and some are permanently welded shut... it's not > obvious that your mechanics shop will have the requisite vacuum connector > to service your shipper. We used to send ours to manufacturer for > reconditioning. > > Best of luck, > > Artem > > On Fri, Oct 18, 2024, 20:23 Pedro Matias <[email protected]> wrote: > >> Dear All, >> >> I'm looking for a low temperature measuring system to check our dry >> dewars, preferably one that is not very expensive. Any recommendations ? >> >> Also, I was told that it is possible to regenerate the vacuum in those >> vessels. Does anybody have any experience with this? 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