Airman 1st Class Christopher Pearce, a 28th Civil Engineer Squadron heating, ventilation and air conditioning apprentice, limits the flow of liquid through a pipe at Ellsworth Air Force Base, S.D., May 3, 2018. The 28th CES HVAC shop is responsible for installing and maintaining all of Ellsworth’s heating, cooling, ventilation and refrigeration equipment. (U.S. Air Force photo by Airman 1st Class Thomas Karol)