Support FAQ

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Centrifuge FAQ

See below for most common centrifuge support questions.

I have unpacked my centrifuge and it is sitting on the bench, what do I do next?

First and foremost, read the documentation and operator’s manual that shipped with your centrifuge for important safety and operating instructions. Then, remove the transport bolts. The documents that ship with the centrifuge indicate where you can find these bolts. Next, put a small amount Hettich grease (supplied) on the motor shaft. This will help you remove the rotor in the future*. The grease prevents the metal from binding after long-term use which can make the rotor difficult to remove*. Finally, install that rotor (if applicable). Use the 5 mm hex wrench (supplied) to tighten the nut in the center of the rotor that secures the rotor to the motor shaft*. *Does not pertain to quick-connect rotors.

What are transport bolts and why must they be removed?

The transport bolts secure the motor to prevent damage during shipping. However, during operation the transport bolts inhibit the centrifuge’s ability to run smoothly. The transport bolts must be removed before operation. For removal instructions, consult the insert included with your centrifuge or consult your operator’s manual.

My new centrifuge is making a loud noise at start-up, what's wrong?

It is likely that your transport bolts are still in place. When installed, the transport bolts do not allow the motor mounts to properly absorb vibrations that can rattle the centrifuge. Consult the insert included with your centrifuge or consult your operator’s manual for instructions on locating and removing the transport bolts.

What is the preventative maintenance schedule of my centrifuge?

Like any equipment, your centrifuge is an investment. You should care for it by cleaning and lubricating on a regular basis. Cleaning your equipment and proper maintenance is Good Laboratory Practice. Lubrication on the pivot points of the rotor (called the trunnions) and buckets will result in better and consistent results. Lubrication also reduces vibration and wear and tear. Operators of centrifuges should check to make sure that the rotor is firmly attached and that the attaching nut is secured on a weekly basis. Visually inspect for any damage and wipe clean the centrifuge chamber and accessories from condensation buildup. Wipe dry the chamber, rotor and accessories to prevent corrosion. Depending on usage, you want to make sure that servicing and maintenance is adequate and consistent with its use. Light use (2-3 times per day) may require lubrication of the rotor pivot points every 2-3 weeks, whereas 24/7 use may require weekly attention. Some lid locks require greasing every 6 months, consult your Hettich representative to determine what your model requires. Validation of the functionality of the centrifuge should be done once every 6-12 months. Reference your operator’s manual for more information on maintaining your equipment.

Why do I need to purchase four buckets when I am only going to use two?

Safety is the key here. Using four buckets applies the g-force load on the rotor in all directions. Using only two across from each other applies force that will actually stretch the rotor in a shape and manner of a football (albeit in an exaggerated manner of speaking) This will then cause the gaps between the rotor trunnions to change widths, rendering the rotor out of spec over time. Centrifuge rotors must always be loaded in the most even manner possible, not just symmetrically. Consult your operators manual regarding even loading vs. symmetrical loading.

What is the difference between G-force (g’s) and RCF?

Nothing. RCF (Relative Centrifugal Force) and g’s are the same unit of measure. They are interchangeable.

If my old centrifuge was set for 5,000 RPM and my new and larger centrifuge is set for the same speed, then why are my results different?

It has to do with the radius of the spin. If you spin a sample at 5000 RPM at 100 millimeters from the center of spin, you will imply a force of 2,795 RCF (g’s) onto the sample. Now, spin that same sample in a larger centrifuge at the same speed (let’s say 130 mm from center) and suddenly you’re at 3,634 RCF (g’s). You raised the force by about 33% simply by using a larger centrifuge! So when you talk about protocols and spinning at a set speed, you need to know the radius of the spin as well to be sure you are still following your laboratory’s protocol. To calculate RPM or RCF for your new centrifuge, try the RCF / RPM calculator.

My centrifuge experienced a Tacho 1 error, how do I clear it?

The tachometer measures the speed of the rotor by counting its magnetic pulses. When a Tacho 1 occurs, the tachometer has missed an expected magnetic pulse. The magnets ring underneath the rotor may be unclean. Check for dirty magnets on the underside of the rotor. To clear the error, open the centrifuge cover and turn off the mains (power) switch. Wait ten seconds and then vigorously spin the rotor by hand. While the rotor is still turning, turn the mains switch back on.

My centrifuge experienced a Tacho 2 error, how do I clear it?

The tachometer measures the speed of the rotor by counting its magnetic pulses. When a Tacho 2 error occurs, the tachometer has not detected any magnetic pulses. The rotor may have not have been tightened completely. Check the rotor. To clear, open the centrifuge cover and turn off the mains (power) switch. Wait ten seconds and then vigorously spin the rotor by hand. While the rotor is still turning, turn the mains switch back on.

My centrifuge experienced an imbalance error, what do I do?

The imbalance detection mechanism has been triggered. Check that the rotor is properly balanced, and also ensure that the rotor is properly greased. If the trunnions of the rotor are not adequately greased, the buckets may have difficultly swinging out, causing an imbalance. After checking the rotor, to clear close the lid and reattempt the centrifugation run.

My centrifuge experienced a mains interrupt error, what is and how do I clear it?

The centrifuge has experienced a power failure during a run. It may simply have been caused by an interruption in the power current. To clear, open the lid and push the start button. Close the lid again, and reattempt centrifugation.

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