•         Cylinders.

•         Regulators.

•         Hoses.

•         Torches. (welding & cutting)

•         Tips.

•         And your PPE.

CYLINDERS

•         Cylinders should be checked regularly with date of the last test stamped on the top of the cylinder.

•         Always stored in the up right position.

•         When not being used, the valve cap should always be in place

REGULATORS

•         The desired working pressures for the torch is accomplished by using the pressure reducing regulator.    

•         The regulator maintains a steady working pressure as the pressure drops in the bottle.

WELDERS WRENCH

•         This tool is most important for any oxy welder as it contains eight (8) open end sizes for all hose connections, welding and cutting tips.

•         There is also a socket to open and close the bottles.

WELDING HOSES.

•         The cylinder regulators and torch usually connected by a double line hose.

•         The oxygen line is GREEN and the acetylene line is RED.

•         Care should always be taken of the hoses and they should be checked daily.

•         Remember to only open the cylinder by ½ turn maximum.

CHECK VALVES.

•         Are there  to prevent flash back (back flow)

•         Always fit the hoses correctly and keep the connections clean

 -Cutting Torces

 - Welding Torches

TORCHES

•         Cutting torch is used for cutting steel by the use of cutting tips.

•         The welding torch takes the welding tips to transfer the heat to the work.

CUTTING TIPS

•         Always clean the cutting tips before commencing cutting

FLAMES

•         Neutral is used for welding most metals including mild steel.

•         Oxidizing is used to braze steel, cast iron and weld brass and bronze.

•         Carburizing is used for welding high carbon steels And non-ferrous alloys.

Safety Notes

•         Gas cylinders must always be secured to a solid structure with a chain to prevent them falling or rolling.

•         Always keep the welding equipment free of oil and grease and away from oily rags.

•         Check for adequate ventilation before welding.

•         Keep all flammable material away from the work area

•         Wear the appropriate welding goggles (shade5) and gloves.

•         Release the regulator pressure screw and open the cylinders slowly.

•         If leaks are detected in the equipment, shut all valves off and report it.

•         Open the acetylene cylinder ½ turn maximum

•         The normal pressure setting for acetylene is 5 p.s.i. with a maximum of 15 p.s.i. Acetylene explodes above 15 p.s.i.!

•         The oxygen cylinder valve should be opened all the way as it is a double seating valve.

•         The normal pressure setting for oxygen is 10 p.s.i. with higher settings use for torch cutting.

•         Point the torch away from yourself before lighting it.

•         Use a friction torch lighter (flint striker) to ignite the torch.

•         Close the acetylene valve first if the torch back fires.

•         Keep sparks and flames away from the gas cylinders and hoses.

•         Never roll equipment over hoses or cords!

•         Close both cylinder valves and then.

•         Do not carry lighters, matches ot othe flammable objects when welding or cutting

•         Release the pressure from the lines when the job is finished.

source : MNL safety briefing

Heat Transfer

 Heat is a form of energy. Every object on earth has some heat energy. The less heat an object has, the colder we say it is. Cooling is the process of transferring heat from one object to another. When an air-conditioning system cools, it is actually removing heat and transferring it somewhere else.

SENSIBLE AND LATENT HEAT

There are two forms of heat energy: sensible heat and latent heat.
Sensible heat is the form of heat energy which is most commonly understood because it is sensed by touch or measured directly with a thermometer. When weather reporters say it will be 90 degrees, they are referring to sensible heat.
Latent heat cannot be sensed by touch or measured with a thermometer. Latent heat causes an object to change its properties. For example, when enough latent heat is removed from water vapor (steam or humidity), it condenses into water (liquid).

CHANGE OF STATE

An object that changes from a solid to a liquid or liquid to vapor is referred to as a change of state. When an object changes state, it transfers heat rapidly.

HUMIDITY

Moisture in the air is called humidity. The ability of air to hold moisture directly relates to its temperature.
The warmer air is, the more moisture it is capable of holding. Relative humidity is the percentage of moisture in the air compared to the amount of moisture it can hold. A moisture content of 70°F air with 50% relative humidity is lower than 80°F air with 50% relative humidity.
When the humidity is low, sweat evaporates from your body more quickly. This allows you to cool off faster. High humidity conditions do not allow sweat to evaporate as well because the air is at its maximum capacity.
Humidity is also a form of latent heat. When air contains more humidity, it has more latent heat

REFRIGERANT

Refrigerants are substances used by air conditioners to transfer heat and create a cooling effect. Air-conditioning systems use specially formulated refrigerants designed to change state at specific temperatures providing optimum cooling.
Portables use a refrigerant called R-22 ( Hydrochlorofluorocarbon) and R -12  (Dichlorodifluoromethane ) This is currently the most common refrigerant used by air-conditioning and refrigeration  systems.

AIR-CONDITIONING SYSTEMS

The system by which air conditioners provide cooling is called the Refrigerant Cycle. This system has four major components common to all air-conditioning systems (see next slide).
These components and their basic functions are listed below.

1. Compressor
   Refrigerant is drawn from the evaporator and pumped to the condenser by the compressor. The compressor also pressurizes the refrigerant vapor so that it will change state (condense) readily.
2. Condenser
   The high-pressure refrigerant vapor releases heat through the condenser coils as it condenses into liquid refrigerant. making it easier to vaporize.
3. Metering Device
   (capillary tube, txv & axv valve) The metering device restricts the flow of liquid refrigerant from the condenser to the evaporator. As refrigerant passes through the metering device, its pressure decreases.
4. Evaporator
   The low-pressure liquid refrigerant absorbs heat as it vaporizes in the evaporator coils.
   The process described above is the Refrigerant System or Refrigerant Cycle. It is the system on which virtually all modern Air-Conditioning and refrigeration is based.

Definition

•         ARC Welding process has the advantage of being relative simple only requiring a power supply, power cables and electrode holder.

•         It is commonly used in construction and jobbing shops.

•         The basic arc-welding circuit fitted with is connected by a work cable to the work piece and by an electrode cable to an electrode holder, which takes the electrode and when contact is made to the work piece the circuit  is complete.

•         An arc is created across the gap and the electrode tip touches the work piece and is withdrawn, yet still remains in close contact.

•         The arc produces a tempeture of about 6500 deg F at the tip.  This heat melts both the base metal and the electrode, producing a pool of molten metal.  The result is a fusion bond.

•         Ensure that your job is well guarded so others do not receive a flash from the welding, also slag from the chipping hammer

Tool

The tools required:

•         Helmet.

•         Earth Clamp.

•         Electrode Holder.

•         Chipping Hammer.

•         Wire Brush

Safety Notes

            Before starting actual arc welding you  should be fully aware of the dangers involved.  The high temperature arc and hot metal can cause severe burns.  In addition the electric arc itself provides an additional safety hazard.

            When welding with the electric arc, there is added danger that the small globules or droplets of molten metal may leave the arc and fly in all directions..  They present a personal burn hazard plus a fire hazard if they fall in inflammable material.

Other dangers associated with electric arc welding are: Electric shock, Burns, Radiant energy, Gases and fumes, Radiant energy, Combustible material, Fire.

To prevent all of those dangers we must :

A. Electric shock

1. Make sure machine is properly grounded.
2. Never permit “live” parts of the electric welder to touch bare skin or wet clothing.
3. Do not cool electrode holders by emersion in water.
4. Turn off power supply when welder is not in use.
5. Do not stand on wet areas while welding.
6. Wear leather gloves.
7. Make sure cable are covered and in good condition.
8. Make certain that electrode holders are properly insulated.

B. Burns

1. Protect eyes and face from flying particles of slag by use of safety glasses or face shield.
2. Wear adequate protective clothing.
3. Always wear leather gloves.
4. Wear high top shoes.
5. Keep collar, shirt pockets, etc buttoned.
6. Do not touch the electrode or metal where welding has taken place.
7. Handle hot metal with pliers or tongs.
8. Keep electrode stubs properly disposed of.

C. Radiant Energy

1. Use a welding helmet with the correct shade lens in good condition.
2. Wear suitable clothing—do not leave bare skin exposed to the rays of the arc.
3. Do not strike the arc without covering the face and eyes.  Give warning to others before striking the arc.
4. Avoid looking directly at the arc where others are welding without proper eye protection.

D. Gases and Fumes

1. Work only in well-ventilated areas.
2. Use great care when working on metals covered with lead or zinc.
3. If working in a confined area use respirator or other approved breathing devices.

E. Combustible Materials

1. Keep shop clean in areas where welding is to be done.
2. Do not weld near combustible materials of any kind.
3. Never weld on covered containers which may have held combustible materials without first taking adequate safety precautions.  For example, fill them with water, steam clean or fill with an inert gas.

F. Fire

1. Be familiar with location and types of fire extinguishers.
2. Report any unsafe conditions that might start a fire.
3. Do not weld near inflammable materials.
4. Do not weld on containers that have held inflammable materials.
5. Do not weld near electrical fittings or lines.