Lamp chimneys are usually made of thin fragile glass and are easily broken. If you still have the parts of your broken chimney, in order to measure for a replacement, you may carefully tape it together with scotch tape. Please be careful not to cut yourself.
If no pieces are available, you can measure the lamp burner itself to determine the needed base (bottom) fitter diameter for a replacement chimney, as shown in the diagrams Below. They may not match your lamp exactly, but will give you the information you need.
Terms you need to Understand:
Diameter is the distance straight across the middle, from one side to the opposite side.
Fitter is the bottom of the chimney that sets into the burner or gallery of the lamp.
Fitter Neck Height is the narrow area below the beginning of a slope which creates the bulge of the chimney. (This is our term, not an industry standard term.)
The most important measurement for a chimney is the base diameter of the fitter. The base must fit snuggly in the burner or gallery so that it will not fall when moved. Most importantly, when fitting a chimney for oil or kerosene use, the chimney must “seat” correctly on the burner hardware to promote bright and efficient lamp fuel combustion .
The chimney helps kerosene lamp burners draw the oxygen they require for combustion through perforations below the combustion chamber. A well-fitting lamp chimney increases the updraft which continues through to the top of the chimney. This updraft helps to cool the metal burner and maintain a steady, flicker-free flame.
A poorly-fitting chimney will allow air to enter the combustion area around the wick from the bottom edge of chimney. If this happens, the flame is pushed about in a cross draft and won’t be able to burn bright and steady. This will seriously degrade the efficiency and light output of the lamp.
Important: Pay special attention to the chimney base-size and fit when replacing a chimney, as it is critical for proper functioning of your kerosene burner.
The final step in replacing your lamp chimney is to try it on the lamp. The best fitting chimney, when placed on the burner, will cause the tines to bend outwardly by approximately 1/8” to 1/4” of an inch. The outward pressure that the chimney places on the tines, creates a firm hold on the light weight and fragile chimney and also helps seat it to insure a proper draft for the burner. Sometimes these tines need to be slightly re-shaped or bent so that all four apply equal pressure on the chimney.
The correct chimney height for an oil or kerosene lamp is not only a question of appearance but, also may determine the efficiency of the lamp burner. Usually, kerosene lamps at use in higher altitudes require taller chimneys for the most efficient combustion. Generally, only lamps that use mantles (Aladdin or Coleman type lamps) for high light output are more seriously affected in this regard than lamps that use flat wicks.
We also have easy instructions on How to Measure for a Electric Lamp Chimney.
Do you have one Light Shade but need another? Or need to replace a Shade which is cracked or broken? Check our helpful instructions on How to Measure Student, Gone with the Wind, Hurricane, Fixture, Ball, and Globe Shades.