When air pressure is first applied to the inlet, air fl ow to the piston is restricted by the adjusting needle. Downstream air pressure grad u all y builds up at a rate deter mined by the set ting of the adjusting needle.

When downstream air pressure reaches the range of 40% to 60% of inlet pressure, the valve element shifts to the full open position and there is full air fl ow to the downstream components. This condition continues as long as there is air pressure at the inlet.

When inlet pressure is re moved, the exhausting down stream air pressure keeps the inlet poppet open until the down stream pressure drops by approximately 90 percent. The remaining pressure is exhausted via the delay orifice. An upstream exhaust port (as in a separate lockout valve) is needed for proper operation.