Our range of inspirated pilots normally draw air from the atmosphere to mix with the gas supply. If the pilot is installed in a classified EEx hazardous area, this means that there is a direct path from the flame at the tip of the pilot back to the area at the back of the pilot, generally below or to the side of an upshot heater.
We have successfully tested our J250E pilot with a flame arrester, certified to ATEX standards for IIC areas. The performance of the pilot is necessarily impaired due to the increased pressure drop through the flame arrester, but the pilot still functions well operating with natural gas or propane, as can be seen on the film clip linked below.
The video shows the J250E torch operating with the flame arrester in place, firing first propane, and then natural gas. This is followed by a comparison of the flame quality firing the same two fuels without the flame arrester in position. Notice at the very end of the video clip the flash back of the flame when the pilot is turned off. It is this danger in a hazardous area that the flame arrester is designed to eliminate.
The tests are clearly made in free air conditions. Inside a heater with negative draft, the performance would be significantly improved. Conversely, the flame quality would be reduced if the pilot was firing against a positive pressure at the pilot tip.