A large user of chilled water used five pumps that would be brought on line in succession as the need for chilled water increased. Each pump used a self-operated back pressure regulator to control head pressure on a common line. Due to droop, the five self-operated back pressure regulators were extremely difficult to balance and lead to pump failure.

Three inch Jordan Mark 56 air loaded back pressure regulators and a Controlair 350 BD loading regulator were used to solve the problem. The one Controlair regulator was used to air load all five Jordan Mark 56 regulators therefore creating a perfect balance of back pressure on all five valves regardless of how many pumps were running at any given time.

Also, this solution was faster acting and much less costly than a series of control loops and provided superior accuracy.