Where required in Section 1111.1, the
maximum setting to which a pressure-limiting device is
capable of being readily set by use of the adjusting means
provided shall not exceed the design pressure of the highside of a system that is not protected by a pressure-relief device or
90 percent of the setting of the pressure-relief device installed
on the highside of a system. The pressure-limiting device
shall stop the action of the pressure-imposing element at a
pressure not more than the maximum setting.
Exception: On systems using nonpositive displacement compressors, the maximum setting of the pressure-limiting device shall not be required to be less than the design pressure of the highside of the system provided the pressure-relief device is located in the lowside, subject to lowside pressure, and there is a permanent (unvalved) relief path between the highside and the lowside of the system. [ASHRAE 15:9.9.2]
Exception: On systems using nonpositive displacement compressors, the maximum setting of the pressure-limiting device shall not be required to be less than the design pressure of the highside of the system provided the pressure-relief device is located in the lowside, subject to lowside pressure, and there is a permanent (unvalved) relief path between the highside and the lowside of the system. [ASHRAE 15:9.9.2]