Hello all,

I'm designing the cascade system for the US market and I have some concerns regarding design pressure according to ASRHAE 15 standard. It says that:
"9.2.6.2
a) The high side design pressure shall be not less than 120% of the maximum pressure developed by a pressure imposing element.
b) The low-side design pressure shall be not less than 120% of the pressure at maximum operating conditions, corresponding to the warmest location in the circuit."

How to determine "the maximum pressure developed by a pressure imposing element"? Is that a pressure which I set on pressure limiting device or is it design pressure of compressor itself?

The part b) does not make any sens to me at all. I'm not a native English speaker maybe that's the problem. Could someone explain it in simpler words?

Thank you guys for your help in advance!
Best Regards,
Adrian