Accurate monitoring of plastic drying process

In plastic production plants, dew point measurement is essential for monitoring the drying process. Tessy Plastics Corporation’s state-of-the-art facilities have been equipped with Vaisala dew point measurement instruments for their drying units, with Vaisala technology also relied upon to cater for other measurement needs in their facility.

Tessy Plastics Corporation is a custom plastics injection molder headquartered in Elbrige, New York (USA). The company manufactures products for the medical, automotive and electronic industries, amongst others. Beside the plant in New York, Tessy Plastics Corporation has facilities in Virginia and China. The facility in Central New York houses a white room and a clean room, with post molding, engineering, design and tool building capabilities.

In order to be able to monitor the operation of plastic air dryers, Tessy Plastics use two Vaisala DM70 Hand-Held Dew-point Meters. The DM70 measures dew point accurately in a wide measurement range, which is important in this application. The Advanced Manufacturing Facility Maintenance Supervisor, Todd Eaton, who is responsible for the maintenance of the plant production machinery, plant facilities, plant engineering and process improvement, stresses that the plastic dryers must operate with dew points below -40°F (-40°C) continuously for proper plastic drying. “Since the first DM70 unit was purchased in January 2002, additional instruments have been installed in our plant and in the drying systems,” remarks Mr. Eaton.

The plant is also equipped with a DMT242 Dew Point Transmitter that was purchased to upgrade one of the dryers. To monitor a dehumidification unit, a Vaisala DMP248 Dew point Transmitter is used. Moreover, a HMP233 with a radiation shield is used to monitor outside conditions, measuring the wet bulb and enthalpy of outside air. This instrument allows the maximization of free cooling potential using outside air. Additionally, the HVAC system at the plant is fitted with HMW40s that were recently installed.

Todd Eaton finds that Vaisala products offer excellent accuracy and repeatability. Moreover, the ability to be interfaced with PCs is important. “The instruments allow the recording and tracking of dew points and other measurements, which in turn allows us to operate our equipment more effectively and efficiently,” Mr. Eaton explains. Vaisala instruments have performed very well and proven excellent for the company.

DMT340 has  replaced DMT248.
DMT143L has replaced DMT242.
HMT330 has replaced HMP233.

The article was first published in  Vaisala News 160/2002.