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avatar: EK86
EK86
1 posts
Replied to EK86's post on September 5th, 2019

Hello,

 

I am having an issue with the ultracentrifuge in our lab. When the temperature is set to 4c, the vacuum fails to fall below 1000microns, though the temperature drops to 4c.

 

If I break the vacuum seal I can hear the air rushing in, meaning there was some sort of vacuum. 

 

If i change the temperature to 25c, then the vacuum will be able to fall below 100 microns. After the vacuum falls, then I set the temperature to 4c and the vacuum remains.

 

What is causing this issue? Vacuum failing to form only when it is cold, but it is able to keep vacuum after reaching proper levels and changing the temperature afterwards.

avatar: dpkleessr
dpkleessr
1111 posts
Replied to EK86's post on September 5th, 2019

First, in my decades of working on Beckman Coulter benchtop ultras, I never saw a problem like you are experiencing. The first thing I would do would be to perform both temperature and vacuum system calibrations. To do this, first close the chamber door and then enter the following keystrokes: [ENTER], 9, [ENTER], [ENTER], 100, [ENTER]. The centrifuge will beep 3 times after the calibration. Next, enter the following keystrokes: [ENTER], 9, [ENTER], [ENTER] 200, [ENTER]. The centrifuge will beep 3 times when the process is completed. As you have discovered, the temperature readout is directly related to the performance of the vacuum system. Cooling/heating of the rotor and chamber takes place via thermo-electric modules underneath the chamber assembly on what is known as the "heat sink". There is a thermistor that actually reads the temperature of the refrigeration can and ultimately the rotor after 4 hours, the two should be at the same temperature. Therefore, if you are looking to perform a run at 4 degrees, please precool the rotor to that temperature and keep the exposure of the rotor to higher temperatures while loading your samples to a minimum in order to prevent temperature rises of the rotor. If the rotor is precooled then it should not take 4 hours to get to the desired temperature. Try those calibrations and get back to me.Don

avatar: EK1986
EK1986
1 posts
Replied to dpkleessr's post on September 6th, 2019

Thank you for the adivce. I will try this today. Will this calibration process take long?

 

I had to create a new user account because something is wrong with the website login. It keeps telling me i have a wrong password even after i resset it.

avatar: dpkleessr
dpkleessr
1111 posts
Replied to EK86's post on September 6th, 2019

The entire process of calibrating the temperature and vacuum systems takes only a few minutes with the temperature typically taking less than a minute. Please let me know how it goes.

The issue with your login probably came about because there are a couple of spammers that have been messing with the site such that they have had to purge some posts although I was unaware that the user accounts were also affected.

Don