Sample Quality| Industrial hygiene & Environment | Safety

Liquid and Gas Sampling  

Toluene Diisocyanate Sampling (TDI, CH3C6H3(NCO)2) Project

Although we have been routinely recognized for our work with hazardous chemicals, at Biar Inc., we also commonly provide sampling solutions for substances with unique physical properties that present their own sampling challenges. Toluene diisocyanate, or TDI, is used extensively in several industrial processes to produce polyurethane foams, adhesives, surface coatings, and elastomers. Although TDI has a relatively low toxicity, OSHA has established exposure limits regarding TDI vapor concentrations in the work environment. Some of the primary challenges associated with TDI lie in its physical properties. Because it is sticky and can solidify at standard temperature, process temperatures may reach over 300°F, and while very minimal exposure is acceptable, excessive exposure can cause maintenance issues as well as a health hazards.

There are two sampling systems we recommend when working with TDI: a valve which terminates in a stainless steel nipple with a bottle support and safety plug; or a multi-function stainless steel valve with a safety plug and either a thread adapter or bottle support. Both of these systems include the use of a safety cabinet and heating jacket for the valve. The system that should be used is determined primarily by customer preference and the specific requirements of the given application.

The use a valve that terminates in a stainless steel nipple is recommended by DOW for TDI sampling and provides direct access to the valve outlet for cleaning. The multi-function valve with thread adapter or bottle support has a removable adapter that facilitates easy cleaning, but this design does not provide direct access to the valve outlet. In both designs, the safety cabinet is used to minimize exposure to the TDI fumes, while the heating jacket maintains the temperature of the TDI for testing and analysis. Both of these systems meet all OSHA safety requirements and provide a reliable, clean way of sampling TDI process streams. For additional information about our sampling valves designed for TDI sampling applications, contact us directly.

Comparison of the Two Recommended Sampling Systems:

  Advantages Inconveniences
Valve which terminate in a stainless steel nipple
  • Easy to clean due to direct access to the outlet of the valve
Multi-function Stainless Steel valve
  • Adapters can be removed easily for cleaning purposes
  • No direct access to the outlet of the valve