A spirometer is a biomedical device that measures lung capacity and lung volume. The construction feature of spirometer is very simple. It basically consists of a container that collects the gas. To understand the basic working principle of a spirometer, we need to look at the basic construction of a spirometer. The water-sealed model is one of the more popular types of spirometer. Let us discuss the construction and working of water seal spirometer for the purpose of understanding.
Water Seal Spiro-meter:
It comprises of a straight, water-filled chamber of 6 to 8 liters limit. Inside the chamber, a modified weighted chime container is joined. The breathing funneling game plan from the lower part of the water-filled compartment is projected over the water level inside the ringer container as displayed beneath.
At the point when an individual inhales into the ringer through the breathing line, the volume of air caught inside it changes. The changing air volume changes the upward development of the ringer container and subsequently the place of the hanging weight changes in like manner. This is on the grounds that the opposite finish of the wire joined to the chime container is connected to the weight through pulleys. The patient inhales air into the cylinder through a mouthpiece. During each pattern of inward breath and exhalation, the container goes all over. It relies upon the volume of air entering or leaving the container.
A weight attached to the string moves up and down depending on the movement of the bell jar. A pen is attached to the weight, which draws a graph on paper attached to a rotating drum. The graph produced is called a kymograph.
The vertical movement of the weight can be converted into an electrical signal to create a display on the instrument screen. In this case, a linear potentiometer is connected to the weight to generate an electrical signal corresponding to the movement of the weight. The resulting graph is a Kymograph. A spirometer is considered a mechanical integrator. The input is the airflow and the volume displacement is the output.