Controlled rate freezers are bought on features and outgrown on chamber volume. Size it against the largest routine batch you expect in three years, not the average one you run today.
What still needs a controlled rate freezer
Sperm, and much tissue and cell banking work, where slow programmable cooling remains standard. For embryos and oocytes, ASRM’s 2021 committee opinion recommends vitrification as standard of care, so those move to kits and carriers rather than a machine.
The four sizes
The CBS Digitcool range is listed as Nano-Digitcool at 11.5 litres, Micro Digitcool at 26 litres, Mini Digitcool at 90 litres and Digitcool at 150 litres.
Matching size to work
A small andrology unit freezing a handful of samples per session does not need 150 litres, and running a large chamber part loaded wastes nitrogen on every run. A tissue bank, or any laboratory batching weekly, will find 11.5 litres limiting inside a year and end up buying a second unit.
Before you order
Confirm the straw or vial holders match the formats you already use, and that the cooling profiles your protocols specify are achievable on that model. Ask for those profiles in writing rather than assuming a range covers them.
