Solders are used to connect copper

tubes. Flux used make the soldering

easy and defect less. Lead and paper

gaskets are used to reduce the leakage

of refrigerants. Petrol,  carbon tetra-

chloride and dilute hydro-caloric acid are

used for various cleaning purposes in


 Solders used in Refrigeration and Air Conditioning

A solder is made up of two metals in a certain ratio  by mass. It has low melting point. A solder is available in the form of a wire or a bar. It makes a permanent connection between brass / copper tubing.

Different solders

There are many types of solders available in the market. But the following three solders are most commonly used in refrigeration and air conditioning.

1. 50-50 solder                                                                                                                                                                                                        It contains 50% tin and 50 % lead. It is used up to a temperature of 1800C. It is most commonly because  it is highly corrosion resistant.

2. 95-5 solder 

It contains 95 % tin and 5 % antimony. It is for soldering in evaporators working below –100C. In this, Antimony improves the strength and mechanical properties of the resulting joint.

3. Silver solder 

In this solder, silver is either 35 or 45 % and remaining  is copper. Silver solder is for high temperature applications. It has high strength. It connects two dissimilar metals.


Fluxes used in refrigeration

Purpose of the flux is to make soldering easier and protect the metallic from oxidation. Fluxes in refrigeration are alcohol and raisins.

Gaskets used in refrigeration

It is a packing material between two  matching metal surfaces. It prevents leakage of refrigerant between two matching parts. Gaskets made of  lead and paper are most common. These gaskets are significantly compressible to prevent leakage. These are available in the sheet form of thicknesses of 1/16”, 1/32” and 1/64” respectively.

Cleaning solutions used in refrigeration

There are three common cleaning agents in refrigeration and air conditioning. These clean the surfaces of dirt, rust and grease.


2,  carbon tetra-chloride

3.  Dilute hydro-caloric acid

It is to clean the tubes in a shell and tube condenser. Mix Hydro-caloric acid and water in the ratio 1:8.