Heat treating of steel is essential to the production of durable products. These products are heated in a furnace to the proper temperature and then cooled by some sort of quench: air, salt, special quench fluid, or oil. The use of oil quenches is wide-spread and the quench facilities generally fall into two categories - open and enclosed. In many Open Quench Tank operations, the parts, as they exit the furnace on the furnace conveyor, drop into an oil bath through a chute onto another conveyor. This conveyor, submerged in the oil, carries the parts through the oil for the prescribed time and then up and out to a washer. A drip pan under the exit conveyor catches the oil drippage, allowing it to drain back into the quench tank.
As production increases and the oil heats, there is increased oil vaporization, which can develop into a fire situation. In the event of fire, CO2 is discharged onto the burning oil surface(s) and the drainboard. If there is an oil coated exhaust, that is also considered part of the hazard to be protected. Heavily oil-coated parts are also a part of the fire hazard. Sometimes the tank oil surface is open or partially open. Other times the tank surface at floor level is covered or partially covered. Chemetron system design techniques can deal with any of these arrangements.
The other Oil Quench arrangement is for the heated parts to leave the furnace in a batch (often a steel basket) to enter an enclosed quench area. The parts are lowered into the oil for the prescribed time, raised out of the oil with the vestibule door closed. When the door is opened, the basket of quenched parts is rolled out on a roll conveyor. Dripping oil is caught in the drip pan beneath the rollers. The internal quench tank is ventilated with the exhaust duct becoming oil coated. The fire suppression consists of coverage of the conveyor and drip pan, and flooding the exhaust duct. CO2 is not discharged directly into the quench enclosure. Some system designs allow for the ability to manually discharge CO2 at the vestibule door in case product gets stuck, blocking the door open. Other features often found in this protection are the use of a "spurt system," where the operator can manually discharge gas at the oil surface where flare-ups occur. The protection of surrounding pits (usually partially oil covered) is also included. In all cases, the most stringent personnel safety features are emphasized in each installation.
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