Which hydrocarbon grease?
Whether you want good thermal contact at 30K, or to seal a joint at 180°C, we have an Apiezon grease to do the job, but which hydrocarbon grease should you choose? Here I take a look at how you can reach that decision.
Below we have divided the temperature range up as follows with the likely candidates
- -273 to -40°C (now that is cold) : Apiezon N grease
- -40°C to 10°C (brass monkeys) : Apiezon N, H or AP101 greases
- 10 to 30°C (ambient) : Any grease in the range!
- 30 to 120°C (toasty) : Apiezon T, H or AP101 greases
- 120 to 180°C (getting a bit hot) : Apiezon H or AP101 grease
- 180 to 240°C (ouch) : Apiezon H grease
Pressure is the next thing to consider, or more accurately how little pressure have you got? The greases all have different vapour pressure curves and this determines which one is going to suit your application at your temperature.
So how do the vapour pressure curves in the datasheets work? Well, the easiest way to look at it is if you are above the curve then there is no outgassing and all is well. Below the curve outgassing might happen and you run the risk of contamination. So for example if your application operates at 25°C and 10-9 Torr then you will want Apiezon L grease.
There are some other factors to think about, radiation resistance, material compatibility and lubricity etc. Of course if you have looked at all the data and are still not sure you can always contact the Apiezon Technical Team here at M&I Materials and we’ll be happy to help you choose the best product.
P.S. If you’re not from the UK then you might have to Google “brass monkeys”.