The Rapidrop model RD053 are Pendent Quick Response frangible glass bulb automatic sprinklers. They are CE Marked, LPCB, VdS, FM approved, UL listed, standard orifice fire sprinklers for installation in fire sprinkler systems. Sprinklers produce a hemispherical water distribution pattern below the deflector. In a fire condition the heat causes the fluid in the glass bulb to expand which shatters the glass and releases the spring seal assembly. Water flows from the orifice onto the sprinkler deflector which diffuses the water into a uniform spray pattern which extinguishes or controls the fire.