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)
1 The common cold is caused by many different viruses. 2  The common cold is transmitted by infected airborne droplets or by direct contact with infected secretions. 3  Being in cold weather does not cause the common cold. 4  Symptoms of the common cold include. 5  cough, 6  sore throat, 7  sneezing, 8  runny nose.ecause so many different viruses can cause the common cold and because new cold viruses constantly develop, the body never builds up resistance against all of them. For this reason, colds are a frequent and recurring problem.