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)
The Common Cold. The Common Cold is caused by a virus. There are over 200 known cold causing viruses the most common being the human rhinovirus of which there are over 100 different strains or serotypes causing about 50% of all colds &plusmn 20%. The remaining 30% to 70% of colds are caused by other viruses.What matters here is that.he Common Cold is caused by a virus. There are over 200 known cold causing viruses the most common being the human rhinovirus of which there are over 100 different strains or serotypes causing about 50% of all colds &plusmn 20%. The remaining 30% to 70% of colds are caused by other viruses. What matters here is that.