Sterling thermostatic bellows for 1/2" & 3/4" 750's, 770's, and 780's, radiator trap, and 69B float & thermostatic trap.
Sterling thermostatic bellows or elements are a sealed liquid filled capusule that close to keep the steam contained in the heating apparatus, and open to allow the discharge of air and condensate when it cools. They are used on radiator or fin tube heating applications. Their operation is simple yet demanding. When steam is present the heat expands the fluid within the capsule causing it to push its outer plunger into discharge seat sealing the steam. As the steam cools it causes the liquid to contract which raises the plunger allowing the air and condensate to discharge.