Electrical Safety - Primary Ex Protection
Hazards are typically created in chemical plants, refineries and paint shops, cleaning equipment, mills and stores of shredded products and in tank installations and loading areas for flammable gases, liquids and solids. Explosion protection defines health and safety in the workplace.
The principle of explosion protection
When a mixture occurs in air under atmospheric conditions with flammable substances in the form of gas, vapor, dust , fibers or ruffles, the explosion hits the workspace. The security setting is a function of pressure, temperature and oxygen. Limitations are therefore necessary. There are three blast factors.
- flammable material
- Oxygen (air)
- Ignition source
Figure 1: Base of explosion
By limiting any of the above factors, one can reduce the probability of primary explosion and protection can be determined accordingly.
Basic / Primary Explosion Protection
Primary explosion protection is a process of reducing the number of flammable substances or atmospheric oxygen to a point that does not ensures no risk of explosion. Open layout and adequate ventilation increase air circulation and flush air. It is not possible to completely replace the atmospheric oxygen in an area where people are working. According to the analytical facts, there are three possibilities of explosion in the presence of flammable gas.
Due to heat - open flame / hot surface/ hot gases
Electrical sparks - opening and closing of contacts, short circuit, static discharge
Mechanical spark - friction , hammering, grinding
The first question arises: is there any form of hazardous material that ally causes an explosion. So what is the quantity of these combustible substances? The explosion potential of an atmosphere must be measured. The implementation and compliance of the ex-primary protection must comply with the rules and standards of the ex-protection.
Primary protective measures against ex
The main objective of ex-primary protection is to avoid hazardous substances. Protective measures are only intended to reduce the probability of occurrence of such materials and their spreadability. The measures must be cost effective. Some of the protective measures are below -
Try usingr non-combustible or less volatile substances or replace critical components if possible.
System parts should be used with inert gases such as nitrogen.
Dilute combustible liquids with a non-reactive material such as water.
Reduce the number of combustible substances.
Humidification of dust is necessary.
Regular cleaning also reduces the amount of dust.
Use enclosures filled with inert substances
Provide natural or artificial ventilation for systems that limit the concentration of flammable materials .
Install a hazardous gas detection system that can provide notification via an alarm or system interrupt.
The flash point of the flammable liquid should be changed by adding other materials such aswater. Otherwise, the processing temperature must be lowered. If the flash point of a flammable liquid is higher than the processing temperature, faults, shutdowns, leaks are checked.
1. Which is not a blast factor?
B. Electric spark
D. None of these answers
Exp lanation - No fire exists without oxygen in the 'air. An electric spark is an ignition source and acetylene is a flammable substance. So A, B and C are the factors of the explosion.
2. Why is ventilation necessary for every workplace?
A. To flush the air
B. Pour circulating the air
C. To limit the concentration of flammable substances
D. All of the above
Explanation - All (A , B, C) are related to each other which are the works of a fan. Ventilation is necessary for a workplace to circulate and flush air which reduces the concentration of combustible substances.
3. What substances are used in the pens?
B. Inert gases
C. Alkaline materials
D. All the above
Explanation - Inert gases do not react with any Material. The enclosures are therefore protected by inert gases.