Telltale Oil Filter and Dump Trap

and out ports, an inlet pressure gauge, a dump trap, and a sump drain port. There is also a pipe plug located in the top for testing the dump trap. Air flows through the in-port and a down- coming tube, and is exhausted into the tank. It then reverses its direction, flows upward to the top of the out-port tube, and reverses direction again to reach the Out-port. Centrifugal forces at the two points of reversal and the slowing of the flow within the tank extract the entrained droplets of liquid. These droplets collect at the bottom of the tank and drain into the dump trap. When the liquid level in the trap rises sufficiently, a float (through a connecting linkage) opens a valve to a waste line, and the collected liquid is blown out. When the float drops, the valve closes and liquid collects until the float automatically initiates another disposal sequence. Operation of the float maybe observed through a transparent trap bowl. The trap is also equipped with a manual drain, which is operated by pulling a button on the bottom of the trap. Telltale Oil Filter and Dump Trap The telltale oil filter and dump trap are located downstream from the fluid separator and dump trap. It is designed specifically to remove oil from compressed air and to indicate by color the state of the oil removing material. This unit further purifies the air by removing small oil droplets that escape the fluid separator. As shown in figure 2-3, the filter employs two direction changes of airflow and impingement surfaces to mechanically remove droplets; a mist separator to help small drops become larger and drop out; and an absorbing material to remove the remainder. The absorbing column, which is visible in a transparent tube, changes color from pink to dark red as it absorbs oil. Before the color change reaches a redline indicator, the filter element should be replaced. Liquid oil drains are collected into an automatic dump trap for discharge into a waste line. This trap is identical to that used on the fluid separator; therefore, the same explanation and comments apply. The combination of the fluid separator and the telltale oil filter removes entrained water and oil and some of the oil vapor from the supply air, provided that these units are properly maintained. Water vapor and any remaining oil are removed in the dehydrator (fig. 2-1), which follows further downstream. Figure 2-3.-Telltale oil filter. 2-5