Model 618, Dry Stylus Recording Oven Thermograph records temperatures up to 500°F (260°C) over 1 or 24 hour time spans. The instrument uses a spring wound precision chart drive which is silicone lubricated to operate at higher temperatures.

The recording surface of the chart is heat resistant and gives a permanent record of the temperature measured over time.The recording charts are calibrated to the bimetallic spiral, which drives the dry stylus, producing the record. The sensor is constructed of ASTM type TM-2 bi-metal alloy. The bimetal sensor is conditioned, annealed, and tested for permanent calibration.The spring wound chart drive requires no power or batteries and is nonexplosive. The instrument and chart movement are independent of any external connections. The clock movement is enclosed and is protected from dust and dirt. The clock mechanism’s warranty is 6 mos.The stainless steel stylus does not require changing, sharpening, or replacing.

The 3-5/8" diameter circular chart incorporates a film on a Teflon coated aluminum base. The temperature-time record is traced on this surface with the stylus. For more permanent storage of a chart trace, a 4" wide strip of clear shipping tape (or similar) can be placed across the top of the smoke chart. Excess tape is then trimmed.

Caution: Do not allow instrument to exceed 500°F (260°C). When replacing a chart, the chart nut should not be overtightened–it should be "just snug".