Smudge pot
From Wikipedia, the free encyclopedia
A smudge pot or "choofa" (also known as 'Orchard Heater') is an oil-burning device used to prevent frost on fruit trees. Usually a smudge pot has a large round base with a chimney coming out of the middle of the base. The smudge pot is placed between trees allowing the heat and smoke from the burning oil to prevent the accumulation of frost on the fruit of the grove.
Throughout the 1900s, smudge pots were commonly used in areas such as California's numerous citrus groves. The smudge pot often became a symbolic prize in local football rivalries. Today rivals Bonita High School and San Dimas High School, in Southern California, compete for a silver plated smudge pot, and Redlands High School and Redlands East Valley High School compete for a half blue, half red pot to symbolize both schools in Redlands, California.
Smudge pot use in Redlands groves groves continued into the 1970s. Pots came in two major styles, a single stack above an fuel oil-filled base, and a slightly taller version that featured a cambered neck and a re-breather feed pipe out of the side of the chimney that siphoned stack gas back into the burn chamber and which produced a more complete combustion. Filler caps have a three or four hole flue control. The stem into the pot usually has a piece of oil-soaked wood secured inside the neck to aid in lighting off the pot. Pots are ignited when the air temperature reaches 32 degrees Fahrenheit, and for each additional degree of drop, another hole is opened on the control cap. Below 29 degrees, there is nothing more that can be done to enhance the heating effects. Some groves also utilized natural gas pots on lines from a gas source, but this are not "smudge" pots in the usual sense, and they represented only a fraction of the smudging practice. Sometimes, large smudge pots are used for heating large open buildings, such as mechanics workshops. In Australia they are called 'choofers' because of the noise they make when lit - 'choofachoofachoofa'.
Lighting an Australian 'choofer' is a tricky business. Because of the voluminous clouds of oily black smoke they produce when cold, they must be lit outside. This is accomplished by holding a burning rag next to the open damper on the fuel tank. The draught caused by the breeze passing through the chimney will draw the flames through the open damper into the fuel tank, where the surface of the fuel inside will light and burn instantly. Once the choofer is sufficiently warm, the damper may be closed until a steady rate of burning is attained, when the characteristic 'choofa choofa choofa' noise is produced. If the damper is not closed, the choofa may choke itself with its own smoke, causing peridoic 'explosions' of unburnt gases in the chimney. Such explosions are not dangerous, but they are noisy and they produce much smoke. Once the heater is burning hot enough, the smoke will dissapear an it may be dragged slowly and carefully inside. They still produce dangerous gas, and must only be used in well ventilated spaces.
Choofers will burn almost any inflammable liquid fuel, including kerosene, diesel or used sump oil, which was arguably the most popular.
