KNOW THE MEANING OF "N95" IN N95 MASKS !!

During the coronavirus pandemic, masks have become a common part of our life. Out of various types of masks N95 masks have become quite famous and are in demand nowadays. But have you ever thought what does "N95" in this mask mean? Let us find out the answer in this article.

N95 respirators and surgical masks (face masks) are examples of personal protective equipment that are used to protect the wearer from airborne particles and from liquid contaminating the face. These are also known as ‘air-purifying respirators’ because they protect by filtering particles out of the air as you breathe. These respirators protect only against particles—not gases or vapors. Since airborne biological agents such as bacteria or viruses are particles, they can be filtered by particulate respirators.”

WHAT DOES "N95" RATING MEAN:

The different ratings in place for respirators indicate how well the mask would protect against oils and are rated as N, R, or P.

N - Not oil resistant
R - Resistant to oil
P - Oil Proof
So, here N means the mask is not oil resistant.

95: Masks ending with 95 have a 95 percent efficiency (Removes 95% of all particles that are at least 0.3 microns in diameter). Masks ending in a 99 have a 99(Removes 99% of particles that are at least 0.3 microns in diameter) percent efficiency. Masks ending in 100 are 99.97 percent efficient and that is the same as a HEPA quality filter.

So, in short, N95 masks are not oil-resistant masks that remove 95% of all particles that are at least 0.3 microns in diameter.

The Centers for Disease Control and Prevention (CDC) does not recommend that the general public wear N95 respirators to protect themselves from respiratory diseases, including coronavirus (COVID-19). The CDC recommends that members of the public use simple cloth face coverings when in a public setting to slow the spread of the virus since this will help people who may have the virus and do not know it from transmitting it to others.

KNOW HOW FUEL GAUGE WORKS IN VEHICLES !

We generally see fuel gauge in cars and motorbikes. They tell us the level of fuel in the fuel tank very accurately. Have you ever imagined how this gauge works and gives us reading that is always correct? We will understand the working of fuel gauge in this article.

The fuel gauge is a simple device. As a rule of thumb, it doesn’t even indicate/calculate the quantity of fuel in liters (or gallons), since all that is needed to alert the driver is the amount of fuel relative to the tank’s capacity. In this regard, fuel gauges have just two main markings – F for Full and E for Empty. Some have a “½” marking, too, to show half-tank.

The basic electromechanical fuel gauge consists of very few parts. The first part of this system is the sending unit. The sending unit is located in the fuel tank of the car. It consists of a float, usually made of foam, connected to a thin, metal rod. The end of the rod is mounted to a variable resistor. A resistor is an electrical device that resists the flow of electricity. The more resistance there is, the less current will flow. In a fuel tank, the variable resistor consists of a strip of resistive material connected on one side to the ground. A wiper connected to the gauge slides along this strip of material, conducting the current from the gauge to the resistor. 

If the wiper is close to the grounded side of the strip ( represented by the circuit in the figure), there is less resistive material in the path of the current, so the resistance is small (and current is high). If the wiper is at the other end of the strip, there is more resistive material in the current's path, so the resistance is large(and current is low).

The second part of this system is the fuel gauge which is a current meter. At low fuel levels the resistance will be high and at high levels the resistance will be low. The current from the resistor goes to a gauge that reacts to the amount of current flow. At high resistance the current will be low and the needle on the gas gauge will be low. At low resistance (full tank) the current will be high and the needle on the fuel gauge will reflect that. This is how the fuel gauge works.

Thank you for reading the article.

KNOW WHY KEY IS USED IN TORQUE TRANSMISSION !!

We come across various mechanical components on day to day basis, But we ignore the functionality of various components. We are going to discuss the functionality of one such component. You might have seen shaft and other mechanical components connected with a key. Have you ever imagined why this key is used? Let us explore the reason for the key in this article.

A key is a machine element that is used to connect a shaft to other machine elements like Gears, Pullies, Couplings, Sprockets or Flywheels. The key prevents relative rotation between the two parts and may enable torque transmission.

The key will have a provision in both the shaft and the machine element which needed to be connected. this is called Keyway. These keys are temporary fastening elements and are subject to the crushing and the shearing stress.

Various types of the key are used in power transmission are square key, flat key, Dowel Key and so on.

WHY KEY IS USED IN POWER TRANSMISSION :

Let us assume a situation where the key is not used in power transmission as shown in the figure below. When there is a sudden rise in torque, there might be chances of slip between components.

The key ensures the connection transmits the load, power & rotation without slipping and within the accuracy requirement of the design. Without the key the components may slip and this might result in loss of efficiency.

Thank you for reading the article.