Bubblers provide a visual indication of flow by showing air or gas bubbles discharging from a dip tube immersed in a liquid in a transparent bowl. The bubble rate is controlled by a stainless steel needle valve in the head casting. Bubblers and Line Traps available with heavy wall transparent bowls made of either plastic or glass. They are rated at 100 PSI and 50 PSI respectively. Either a ring type or strap type configuration is available for securing the bowl to the head.