[3dem] pressure failure with Leica EM Pact2?

[benoit.zuber at ana.unibe.ch]

Hi Gongpu,

One more test suggestion: does this behaviour happen with more than one type of specimen carrier (e.g. Membrane carriers vs copper tubes)? I have experienced with two EMPACT2 machines that after a few years of usage the tubes burst if you shoot at 2000 bars and you get a complete pressure failure, but this is not the case here. The solution to this tube problem is simply to reduce a bit the pressure, to around 1900 bars. Since we do CEMOVIS, we can check by electron diffraction that the sample is indeed vitrified so we are not worried to work slightly below the optimal pressure value.

Best wishes
Ben

De : 3dem <3dem-bounces at ncmir.ucsd.edu<mailto:3dem-bounces at ncmir.ucsd.edu>> on behalf of Paul Verkade <bixpv at bristol.ac.uk<mailto:bixpv at bristol.ac.uk>>
Date : mercredi, 7 octobre 2015 18:00
À : "Zhao, Gongpu" <goz1 at pitt.edu<mailto:goz1 at pitt.edu>>
Cc : "3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>" <3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>>
Objet : Re: [3dem] pressure failure with Leica EM Pact2?

Hi Gongpu,

Indeed pressure should go up to around 2050 bar.

A few things to check (which you probably already did).
If you turn the blue knob on the side you can adjust the pressure, try adjusting that.
Is the incoming pressure from the compressor OK (about 10bar)?

Let me know if it works (or not), otherwise I can think of a few other things to try / check.

Good luck,
Paul
__________________________________
Paul Verkade PhD FRMS
Reader in Cell Imaging
Wolfson Bioimaging Facility
Schools of Biochemistry and Physiology & Pharmacology
Biomedical Sciences Building
University of Bristol
University Walk
BS8 1TD Bristol
United Kingdom

tel.+44-117-3312179
Fax. +44-117-3312168
mail: p.verkade at bristol.ac.uk<mailto:p.verkade at bristol.ac.uk>
websites:
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On 6 Oct 2015, at 20:42, Zhao, Gongpu <goz1 at pitt.edu<mailto:goz1 at pitt.edu>> wrote:

Dear All,

We are experiencing a pressure failure problem during high pressure freezing using Leica EM Pact . For successful freezing, the curve is smooth and pressure should go up to 2000 bar. But right now, the curve is fuzzy, at some points it drops and the small display shows the pressure is failure. I have attached an image of the bad curve.  Any insights about what might cause the problem and how to fix it would be greatly appreciated? Thank you very much.

gongpu

GONGPU ZHAO, PH.D.
Research Associate
Department of Structural Biology
University of Pittsburgh School of Medicine
3501 5th Ave. RM2054, Pittsburgh, PA 15260

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