The automatic cab signal system shall be arranged so that cab signals will be continuously controlled in accordance with conditions described in Â§ 236.205 that obtain at least stopping distance in advance. Â§ 236.512 Cab signal indication when locomotive enters block where restrictive conditions obtain.
Dissolved oxygen (DO) is a measure of the quantity of free oxygen molecules in water. The concentration of DO is an important indicator of the health of an aquatic ecosystem because oxygen is essential for almost all forms of life. Oxygen is necessary for respiration and for some chemical reactions.
As the temperature goes up, water releases some of its oxygen into the air. Water also holds less dissolved oxygen at higher elevations because there is less pressure. Solubility of dissolved oxygen also decreases as salinity increases. Dissolved oxygen refers to the amount of oxygen contained in water. Oxygen has limited solubility in water usually ranging from 6-14 mg/L. Dissolved oxygen reflect an equilibrium between oxygen producing processes and oxygen consuming processes.