A bad gas valve will not allow any gas to go to the burner or pilot light. See the article on 'Hot Water Heater Gas Valves' for the issues surrounding this device. A clogged or partially clogged vent can cause this problem. See Venting a Gas Water Heater for information on keeping your vent clear.
Definition. A hemoglobin test measures the amount of hemoglobin in your blood. Hemoglobin is a protein in your red blood cells that carries oxygen to your body's organs and tissues and transports carbon dioxide from your organs and tissues back to your lungs. If a hemoglobin test reveals that your hemoglobin level is lower than normal, it means you have a low red blood cell count (anemia). Anemia can have many different causes, including vitamin deficiencies, bleeding and chronic diseases.
Hemoglobin is the main component of red blood cells and serves as the transporter for oxygen and carbon dioxide in the blood. Hemoglobin concentration (Hb) is usually reported as grams of hemoglobin per deciliter of blood (g/dL). Hb is commonly measured by the cyanhemoglobin (hemoglobin cyanide) method. A sample of blood is diluted in a solution of potassium ferricyanide and potassium cyanide, which oxidizes hemoglobin to hemiglobin (Hi; methemoglobin) and then converts it to hemoglobin cyanide (HiCN). The concentration of HiCN is then measured by spectrophotometry.