Rapidrop RD043 – Quick Response Pendent Sprinkler Head, K115 (K8.0), 3/4” NPT, 68ºC quick response, frangible glass bulb automatic sprinklers. These sprinklers produce a hemispherical water distribution pattern below the deflector. In the instance of fire, 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 that extinguishes or controls the fire.