During a fire conditions, the thermal-sensitive liquid in the glass bulb expands, causing the bulb to shatter, releasing the button and spring seal assembly. Water flowing through the sprinkler orifice strikes the sprinkler deflector, forming a uniform spray pattern to extinguish or control the fire.Temperature Rating: 155°F (68°C)Discharge Coefficient: K=5.6(U.S) /80(Metric) Nominal Orifice Size:1/2"(15mm) Maximum Working Pressure:175psi(12bar) Min. Operating Pressure: 7psi (0.48bar) Factory Hydrostatic Test: 100%@ 500psi (34.5bar) NPT: National Pipe Tapered is common in plumbing and some industrial uses. Sometimes referred to as pipe thread because PVC pipe and schedule 40 pipe are typically threaded in NPT. As its name implies this is a tapered thread so that the outside diameter of the male (ODM) gets smaller towards the end of the fitting and the inside diameter of the female narrows with depth. As the two fittings are threaded together the opposite tapers force thread friction and makes the seal without the use of a gasket.
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size
make sure you order the correct size the new models are smaller