Answer :
A TXV with a vapor charge bulb, sometimes referred to as a critical charge bulb, is often called a maximum operating pressure (MOP) valve.
What is vapor charge bulb?
Vapor charge bulb is a charge in a thermostatic expansion valve bulb that boils to a complete vapor. When this point is attained, an increase in temperature will not have any effect on pressure.
The complete evaporation of liquid take place. So, it is also called the critical charge bulb.
Thus, A TXV with a vapor charge bulb, sometimes referred to as a critical charge bulb, is often called a maximum operating pressure (MOP) valve.
Learn more about vapor charge bulb.
https://brainly.com/question/10628249
#SPJ1