I have a simple question

How to keep the vapour concentration of HCl above a HCl-H2O mixture constant when the solution is at 60°C. I know you can get an azeotropic mixture with ~20.2% HCl in water which boils at ~108°C, but I am not interested in boiling the mixture. I am keen on getting a constant HCl vapour composition at 60°C. The maximum I can go is 80°C, but I would rather not!
Your help is anticipated & appreciated
