Archive for September, 2010

Azeotrope & Fractional Hermetric Sealed Compressor

September 24, 2010

It’s common to carry at least 6 different refrigerants in the van.

These are called “Azeotropes”.

What is Hermetically Sealed Compressor?

In hermetically sealed compressor, the compressor and the motor are enclosed in the welded steel casing and the two are connected by a common shaft. This makes the whole compressor and the motor a single compact and portable unit that can be handled easily. The hermetically sealed compressor is very different from the traditional open type of compressors in which the compressor and the motor are different entities and the compressor is connected to the motor by coupling or belt.

Interesting cookware article

September 8, 2010

Common materials of pots, pans

Choosing the right cookware is often driven by the food products cooked in an establishment, type of heat source used, funds available for purchase and personal preference. Here are the most common materials used in cookware and how they stack up to each other.

Aluminum:

Aluminum cookware is a porous metal that is very responsive to changes in temperature, heating up as quickly as it cools down. Pans can be used on both gas and electric surfaces. They can be cleaned using low alkaline detergents.Aluminum cookware is manufactured using either 1100 series or 3000 series aluminum alloys.The 1100 series is nearly a pure aluminum. This soft alloy is more likely to warp and dent. Warping causes a pan to be unlevel on the stove and dents may cause hot spots where food can burn or scorch. In the 3000 series, two common alloys are used, the most widespread being 3003, which contains aluminum, copper, iron and manganese. The less common but more durable alloy is 3004, which also contains magnesium. The additional magnesium hardens the aluminum and adds strength to the pan.

Stainless Steel:

Stainless steel is a non-porous metal that heats and cools slower and more unevenly than aluminum.This material provides flavour neutrality. Also, with a nonporous cookware surface like stainless steel, many chefs feel they can release more of the caramelized fat on the bottom of a pan (known as the fond) back into the sauce they are preparing, which makes the sauce more flavourful. While light coloured sauces may become discoloured in aluminum pans because of its porosity; this will not occur with non-porous stainless steel. Cookware made of this material is also non-corrosive; it will not pit from the use of heavily acidic foods. Additionally, stainless steel is dent- resistant and maintains its appearance. To preserve its beauty, wash cookware by hand in hot, soapy water.

Cast iron:

A ferrous metal, cast iron conducts heat more slowly than stainless steel but will maintain heat well. For this reason, it is a favourite for brazing or stewing meats.However, cast iron is heavy to handle, must be hand washed and thoroughly dried to protect it from rust. It also requires constant seasoning to create a non-stick surface for cooking and prevent food from interacting with the iron on the pan. This process involves cleaning the cookware to expose the bare metal, applying a layer of animal fat or vegetable oil and then heating the cookware to bond the fat to the metal.

Carbon Steel:

Carbon steel cookware is thinner and lighter than cast iron, transmits heat quickly and is a favourite for high heat cooking, which is why its commonly used in woks. Like cast iron, carbon steel is a ferrous metal, so it works well with induction cooking, and requires seasoning.

Clad Cookware:

Clad cookware is typically non-ferrous stainless steel inside, providing the advantages of stainless steel cookware, and ferrous stainless steel outside, providing induction capabilities. Sandwiched between the layers is aluminum, copper or carbon steel, the most common being aluminum. The sandwich material reduces the heating reaction time.
There are two types of clad cookware: fully clad and clad bottom. Fully clad cookware spreads the heat evenly at the bottom and up the side walls. Clad bottom heats primarily at the base of the pan. For each, wash by hand in hot, soapy water to maintain beauty.