Thermal sweeper

The thermal sweeper is a commercial product licensed to Zoex Corporation, Lincoln, NA, USA (16). The sweeper incorporates a slotted heater (operated at about 100 °C above the oven temperature) which passes over the capillary column (normally an intermediate thicker film column is used in this region as an accumulator zone). Eigure 4.3 is a schematic diagram of how the instrumental arrangement may be considered. The greater temperature of the rotating sweeper forces the solute which has been retained in the phase in the accumulator section to be volatilized out of the phase into the carrier gas stream, and then bunched up and brought forward... 

Figure 4.3 Schematic diagram of a thermal sweeper system located between two columns in the gas cliromatograph Cl, C2 and C3 are column connections, with C2 being small enough to allow the slotted heater S to pass over the connection. The accumulator column A retards the travel of solutes tlnough this section until the sweeper expels them out to the uncoated column (called a pigtail (P)), wliich then delivers them as a naixow band to the second column. The modulation drive, M, is external to the GC oven.

It is possible to replace the air in inflatable tires by polyurethane foam. This is feasible for low-speed vehicles used in road construction, service equipment, snowplows, street sweepers, as well as many other applications. The two components are blended together to produce the resilient foam in the tire which is then not susceptible to flats or punctures, a feature which reduces downtime and tire replacement costs. Polyurethane foam (closed cell) has a thermal conductivity of 0.022 Wm and is usually covered with aluminum foil to reduce the heat loss due to the transmission of radiation. 

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