Seclusion, defined as placing a child in a locked room, is prohibited. A locked room includes a room with any type of door-locking device, such as a key lock, spring lock, bolt lock, foot pressure lock or physically holding the door shut.
55 Pa. Code § 3800.206
This section cited in 55 Pa. Code § 3800.171 (relating to safe transportation); and 55 Pa. Code § 3800.273 (relating to exceptions for secure care).