A sprinkler assembly can utilize an adapter having straight threads and an internal sealing member therein to attach the sprinkler to a piping system. The sprinkler may include tapering threads that engage with the straight threads of the adapter and compress the sealing member therein to form a fluid-tight seal. A sprinkler assembly can utilize a fitting that is attached to an extension member containing the sprinkler. The fitting allows the sprinkler and extension member to be coupled to the piping system with a solvent weld. A sprinkler assembly can utilize an attachment system to couple a sprinkler attached to an extension member to a piping system. The attachment system can include a first fitting attached to the connection member, a second fitting attached to the piping system, and a clamping member to clamp the two fittings together.