At the end of steam mains which works periodic (8 hrs per day) thermostatic air vent is installed.
I wonder if there should be fitted check valve after thermostatic air vent to prevent air to come back when steam line is cold.
What do you think?
If you do not have air in the line what will be there instead? Vacuum? Condensate? Choose what you want and design to assure it. Air seems a good choice in many cases.
YES! But in addition, use of thoroughly dry air is almost always a necessity for good pneumatic systems--particularly where freezing temperatures can be anticipated.
Valuable advice from a professor many years ago: First, design for graceful failure. Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs. Only then can practicality and economics be properly considered.