Hobs - Did you know?

The hob is used for boiling, frying, steaming, simmering and braising. It primarily works by the conduction of heat from the flame through the pan surface. A certain amount of radiant heat is also generated. A large volume of primary air is provided so that the pan can be located as close as possible to the burner head and so gain the heat from the flame. The flame should not be allowed to lick up the side of the pan as heat will be wasted. 

The hotplate is usually a solid steel flat plate or ceramic surface, on which the pan sits, or it can take the form of a griddle, which is used for dry-frying foods such as eggs etc. The flame is located beneath the metal and heats it to the desired temperature.

The heat setting of a hob or hotplate often has a grading, such as simmer, medium and high. The flame does not adjust to the heat requirements of the food being cooked and if set too high, the contents of the pan may boil over or burn. Some appliances have thermostatically controlled burners. They work using a contact sensor that is filled with a volatile fluid that, when heated, expands forcing the gas valve to close down to a by-pass rate. With freestanding cookers all control taps and the oven thermostat are located on a pipe, named the float rail, which is located behind the control knob fascia. During any maintenance work all these gas connections should be sprayed with leak detection fluid to ensure they are gas tight. The gas burners used with the associated parts of the cooker are generally unprotected, in terms of flame failure. This means that should the flame go out, gas is allowed to discharge freely into the room. The oven will be found to have a flame failure device fitted, usually of the liquid vapor type, which will shut down the main flow of gas but will still allow a discharge through the by-pass. Cookers supplied by LPG are controlled and all control taps generally require the operation of a thermo-electric FSD before gas is allowed to flow freely. 

The Grill - did you know

The grill is used for toasting, grilling or browning previously cooked food. It works

by directing radiant heat that has been produced on the surface of a red-hot fret,

mesh or gauze surface, on to the food. There are two designs of grill.

First, those referred to as conventional grills, as they have been around the longest.

The grill consists of a pressed steel burner, fed via an injector at one end and located

beneath an expanded metal fret. The flames, on leaving the burner, heat the metal fret

and cause it to glow red-hot. The combustion products rise by convection through

holes in the canopy top. The biggest problem with this design is the problem of

uneven cooking, a result of the burner failing to heat the whole surface of the fret

uniformly.

In the second design of grill, known as a surface combustion grill, the injector feeds gas

into the primary air intake, this entails some 80–90% of that required for combustion.

The mixed gas and air now travels to the centre of a sealed chamber, which has a fine

metal mesh burner surface where the ignition probe is located and where combustion

takes place, the air/gas mixture clings to its face, producing an evenly heated radiant

surface across the entire burner.

Deep Fryers - Did you know

 Deep fryers:

These are appliances that hold a quantity of oil or fat in which food such as chips, fish and doughnuts are cooked. There are two different designs - one that has a flat bottom with the oil heated directly from below and a second type has oil that is heated at a location above the base so maintaining a cool zone below the flame in which old food particles can sink without carbonizing and spoiling the flavor of the food load. There are two methods of heating the oil using this design of fryer. In the first method there is what is known as a V-shaped fryer, with the lower V section below the burner. The second method requires the gas flame to be fired directly into tubes that pass through the mass of the oil. With the flat bottom fryer it is essential that, before each frying all old particles are strained from the oil. The heat input can vary between 8 kW and 40 kW depending on the size of fryer.

Grill and Salamanders - Did you know

Grill and Salamanders

Under-fired or flare grills give a heat source below the food, operating up to 30 kW. The grill consists of a burner firing upwards on to a bed of refractory ceramic or pumice material. The food is placed on a series of bars. As the hot fat from the food drops, it is burnt off in the form of an ‘uncontrolled’ flame, giving the meat a characteristic appearance and flavor. 

Horizontally fired grills use surface combustion plaques between 3 kW and 12 kW and are often accompanied by a rotisserie to cook food. The fat from the food can drop to be collected in a container at the base. Over-fired grills or salamanders have the heat source above the food and operate between 5 kW and 16 kW. They can also be used for toasting. This type of grill often has a grooved solid aluminum branding plate on to which the food is placed. This plate allows the hot fat to drain away but at the same time assists in cooking the food on both sides due to absorbed heat that is held in the aluminum plate.

Salamander

Grill

Dangers of CO (Carbon Monoxide) and the Effects of CO in the Air

                             Carbon Monoxide

What is Carbon Monoxide?..

Carbon monoxide, or “CO,” is an odourless, colourless gas that can kill you. CO in the environment can have a devastating effect on human health. For most of us it would be the most dangerous gas we might ever experience. It is often referred to as the ‘hidden gas’ because it is very hard to detect. However, the effects of CO are quite dramatic and in high concentrations it will kill within a few minutes.

When we breathe, our lungs absorb oxygen. However, CO is absorbed more readily into the blood stream than oxygen and when our haemoglobin, or red blood cells, become saturated with CO, no oxygen can be absorbed. One of the functions of oxygen is to remove waste matter from our tissues, so without oxygen our blood rapidly become poisoned. 

What percentage of CO can be harmful and what percentage can kill us?

CO in air  -  0.01%

Saturation of CO in blood  - 0–15%

Effects of CO in adults - Slight headache after 2–3 hours  

 

CO in air  -  0.15% - 0.3%

Saturation of CO in blood - 50–55%- 55-65%

Effects of CO in adults - Severe headache, nausea, and dizziness within 10 minutes; increased breathing and convulsions, leading to collapse, possible death after 15 minutes.

Yellow flames coming out from gas appliances is a sign that your appliance isn't burning correctly and efficiently. Thus, its important to keep your appliance in good health by servicing it regularly. 

What distinguishes LPG from other members of the family of petroleum hydrocarbons - Part 1

                     Liquified Petroleum Gas

 LPG: is a petroleum hydrocarbon which is a liquid when stored under moderate pressures and a gas when released at normal ambient temperatures. It is inherently safe, and is generally only dangerous if it is escaping. Its vapor pressure increases rapidly as the temperature increases. When the gas is released to atmosphere at ordinary temperatures, it expands rapidly.

It is heavier than air and care needs to be taken not to allow leaks where significant amounts of gas is going to accumulate. Within the flammable limits of LP-gases, a single spark can easily ignite the product. Because it is odourless, approved odorants must be added. Finally, LP-gases are considered non-toxic. However, in confined spaces LP-gases can displace oxygen. Due to decreased levels of oxygen, this condition can cause unconsciousness or death.     

Thermocouples: What are they?

                                                               Thermocouples

The thermocouple is a vital safety feature for many gas appliances. A thermocouple uses the heat from a flame to produce a millivoltage that controls a gas valve. If the pilot goes out, the thermocouple can no longer send the millivoltage that is required to allow the gas valve to stay open, thus sealing the valve to prevent a dangerous gas leak.

Thomas Johann Seebeck accidentally discovered the Thermocouple in 1821. He experimentally determined that a voltage exists between the two ends of a conductor when the conductor's ends are at different temperatures. His work showed that this voltage is proportional to the temperature difference. His discovery soon became the basis of the thermocouple, which today is one of the most popular and cost effective temperature sensors.

Gas Regulators - what are they and how do they work?

 What is a gas regulator?

A gas regulator, also known as a gas pressure regulator, is a mechanical device used with a gas cylinder. It’s designed to slow down the compressed gas rushing out of a cylinder and release it in a controlled and steady stream to the appliance it’s connected to.

Which one is right for you?

There are all kinds of gas regulators available. Choosing the correct one for your installation or appliance is extremely important. First we have to understand why we need one and if it should be used indoors or outdoors.

This is your common low pressure regulator with a gauge. This is used on cooking appliances and heating appliances. This is attached to a 9 Kg bottle and will be connected to the appliance.  

This is a low pressure bullnose regulator. This one is ideal for outdoors installations and should be mounted against a wall. This regulator is for bigger sized cylinders like the 19 Kg or 48 Kg.

 

Green Living with LPG.

The world is moving towards a greener future with businesses and every day civilians becoming more self-aware of their carbon footprint.

These days people are opting for more environmentally friendly alternatives in their daily practices. Single-use plastics are being phased out for reusable alternatives, plant-based foods are becoming more popular by the day and alternative energy sources are being seen more frequently.

LPG is Liquified Petroleum Gas, also referred to as LP Gas or propane. It is a mixture of natural gas and propane. It is a portable, clean and efficient energy source that has many applications and is readily available world-wide. 

It's carbon footprint is 50% less lower than coal and produces virtually no particulate matter or soot when burned making it a clean-burning energy source. LPG is the perfect back-up fuel to use in conjunction with other eco-friendly alternatives such as solar power.

LPG can make daily life more convenient in the following ways:

- Gas Heaters used to heat your home and office.

- Gas Geysers used to heat water instantly.

- Gas Braais provide a stable heat when braaiing with very little cleaning afterwards.

- Gas stoves & hobs used for indoor cooking.

- Gas fireplaces used for indoor and outdoor heating.

LPG is even used to fuel vehicles. A simple, inexpensive conversion can be done so that your car can run on Autogas, making your vehicle duel-fuel. Your car will be able to alternate between using Autogas and petrol or diesel.

Once again, Autogas is a more eco-friendly vehicle fuel as it produces 96% less carbon emissions than diesel and 68% less than petrol.

With increasing electricity prices in South Africa and more load-shedding being implemented every year, #LPG is a great alternative fuel to use at home.

Why Service your Gas appliances?

Why should you service your gas appliances?

LPG is a fantastic alternative energy source to use in your home especially, in South Africa where loadshedding impacts our quality of life.

You can still cook, have access to warm water and keep your house warm with LPG home appliances. 

Just like you service your car, regular servicing of your gas appliances is fundamental in ensuring that they operate safely and use gas more efficiently. Efficient gas usage means you save money on gas as your gas will last longer.

If you experience any of these problems, it may be a good idea to book a service for your appliance:

The gas jet is blocked:

The first potential cause of your problem to consider is a blocked gas jet. The jet (or injector, as it can be known) serves to inject the gas into the burner cup. It is perforated on top with a hole of a very precise diameter to ensure the gas is delivered at the correct rate. If this hole is partially blocked (by liquid for example), the flow of gas will be affected, and this will end up having an impact on the quality of the flame, which will not burn correctly.

The openings on the burner crown are obstructed:

Bad quality flames are frequently caused by obstructions or blockages in the openings on the burner crown. These can get blocked by dirt, fat/grease, spilt liquids and even residual water left behind after the hob has been cleaned.

These are the most common problems that your flame will not burn properly. There are many reasons why you could experience issues with your gas appliance, some of these may even be due to your gas installation or gas set-up.