A check valve, clack valve, non-return valve or one-way valve is a valve that normally allows fluid (liquid or gas) to flow through it in only one direction. Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to leave.
Some causes of cold intolerance are: 1  Anemia. 2  Anorexia nervosa. 3  Blood vessel problems, such as Raynaud phenomenon.  Chronic severe 1  illness. General poor health.  Underactive thyroid 1  (hypothyroidism) Problem with the hypothalamus (a part of the brain that controls many body functions, including body temperature)
If you tend to get colds that develop suddenly and occur at the same time every year, it's possible that you actually have seasonal allergies. Although colds and seasonal allergies may share some of the same symptoms, they are very different diseases. Common colds are caused by viruses, while seasonal allergies are immune system responses triggered by exposure to allergens. Treatment of a common cold may include rest, pain relievers and over-the-counter cold remedies, such as decongestants.