Building on a legacy of PID development

Summary
From the 1970s to the present day, photo- ionisation detectors (PIDs) have been at the front line of efforts to detect volatile organic compounds. As industrial hygiene has become ever more important and exposure limits for VOCs have reduced, PID technology has continued to develop, providing reliable detection under challenging environmental conditions at concentrations right down to below 10 parts per billion.

Introduction
When in the early 1970s it was realised that vinyl chloride, the precursor to PVC, was responsible for an elevated incidence of liver cancer among employees at vinyl chloride plants, exposure levels that had been set at 500 ppm were quickly reduced in response to the threat. Finding a reliable detector for the compound was paramount.

PID Helps Address The Vinyl Chloride Crisis
The process to produce vinyl chloride starts with either natural gas (predominantly methane) or acetylene. In the 1970s the technology available to detect and measure vinyl chloride was the Century OVA 128, a portable FID (flame ionisation detector), but this also responded to natural gas and acetylene, making reliable detection of vinyl chloride a challenge at the more stringent levels proposed. A detector was needed that exhibited no light hydrocarbon interference.

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