Introduction

In this project we are giving dry heat to surgical masks and trying to make it reusable by destroying the virus population deposited in it. As face mask is intended only for single use, during this crisis period we are trying to make it reusable by applying a disinfection treatment. This process is helpful particularly in rural areas and places where economic condition is not stable. The disinfection time is comparatively less and its cost is comparatively low. Our project requires a basic heating system. As this machine is portable, it is suitable to install at the desired places.

Apparatus Required

1. Transformer
2. Diode
3. Capacitor
4. Resistor
5. IC 555
6. Digital temperature display
7. 100 watt bulb
8. Switch
9. Holder
10. Box
11. Aluminum foil
12. Hard board

Block Diagram

Working principle

The timer circuit or mono-stable vibrator operates through 12 V DC. The mid-point full bridge rectifier converts 12 V AC into 12 V DC and filtered by the 470 µF capacitor. The advantage of using a mid-point rectifier circuit is, to get full wave rectification using only two diodes instead of four. The LED in series with 1 kΩ resistor is just for power indication purpose.

We have to make the timer circuit by using a NE555 IC. Pin 4 and 8 are connected to positive terminal. Pin 1 connected to ground. A 10 kΩ resistance is given between pin 2 and positive terminal. A reset switch is inserted between pin 2 and ground. A 0.01 µF mica capacitor is connected between pin 5 and ground to reduce noise. Pin 6 and 7 are shorted together and a resistance is connected in between the shorted point and positive terminal. A capacitor is given between the shorted point and ground. Output is taken from pin 3. When we push the button, the LED glows for a specified time and then it will be off automatically. To drive the relay for that specified time we use transistor bc547.

The infected mask is kept inside the box and the cover is closed. The time equation for our timer circuit depends on the value of a capacitor and a resistor.

Time (in second) = 1.1 X R X C

Where R is the resistance in ohm and C is the capacitance in farad. After switching on the timer circuit, the 100 watt bulb starts glowing for 20 seconds to produce heat. The digital temperature display reads the interior temperature of the box. The digital temperature display used here can read maximum 80°C. For demonstration purpose we have set the timer for 20 seconds. After 20 seconds the bulb is turned off automatically. Now by getting dry heat the mask is free from viruses and ready to use again.

Scientific reason

Research claims that by applying dry heat, the covid-19 can be killed deposited at the surface of an object. The list for time and temperature range to destroy covid-19 virus is listed below.

Advantage

1. It is applicable in rural areas and in those places where economic condition is not stable.
2. The disinfection time is comparatively less and its cost is comparatively low.
3. As this machine is portable, it is suitable to install at the desired places.
4. Anybody can operate this machine easily due to its simple operation.

Enjoy the making video below…