What temperature range is safe for my NMR tube?

For whatever reason, if the sample temperature must be chilled down, or oppositely heated up beyond room temperature, the recommend glass of choice is ASTM Type 1 Class A glass. NMR tubes made from this glass type have thermal expansion rates 60% less than that of standard boro-silicate glass. Since some NMR tubes require withstanding temperatures down to -70 ^oC or up to +200 ^oC, the increased expansion rate can cause conventional boro-silicate NMR tubes to crack. We have a full line of NMR tubes that are made from ASTM Type 1 Class A glass under the “Select Series” Brand, which you can see on our web page www.nmrtubes.com.

Why does one brand of NMR tubes fit differently into my spinner turbine than another brand?

Some brands of NMR tubes have outside diameter variations that present problems when loading sample into a spinner turbine, such that serious damage will occur to the NMR probe. Special care must be taken with stringent attention to quality control when monitoring NMR tube production, so that outside diameter variations are held to a minimum. In Norell’s manufacturing process, with the use of state-of-the-art equipment, NMR tube outside diameter variations are held to extreme minimums.

Keep in mind that spinner turbine o-rings can be worn out too and need replacing. From field tests we have found that spinner turbines also vary considerably in bore inside diameter and are not not manufactured as precise as glass NMR tubes. It is therefore recommended to service spinner turbines periodically along with replacement of the o-rings.

What pressure can my Norell NMR tube hold?

Some reaction mixtures that are out-gassing in the NMR tube, or air-sensitive samples that require pressurizing the NMR tube with inert gas would require the NMR tube to withstand pressure without failure. This question is asked quite often and the formula bellow provides the solution. Please keep in mind that there are also other factures that can cause tube failure under pressure, such as a worn out and scratched tube. Scratches are weak points in glass, and our suggestion is to always use a new NMR tube with samples that require sealing samples under pressure.

Maximum allowable pressure P_max = NMR tube wall thickness (mm) / NMR tube O.D. (mm) X 2,000 psi

Example : 0.38mm/5mm X 2000 psi ≈ 150 psi