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.
How to Measure Blood Oxygen. Pulse oximetry and arterial blood gas tests are methods to measure how much oxygen is in your blood. Normal oxygen saturation levels range from 97% to 99% in healthy people. When your blood oxygen is too low, it's called hypoxemia.