Abstract: A string dispenser for dispensing string from a spool comprising a hollow core, the string dispenser includes a base plate formed with a recess in an upper surface of the base plate for receiving a lower end of the hollow core. The base plate is also formed with a hole that opens at an upper end in the recess and at a lower end at a lower surface of the base plate. An end of a length of string wound on the core can be threaded downward through the hollow core and through the hole in the base plate. The string dispenser also includes a cover for covering the spool of string positioned with the lower end of its hollow core in the recess. The cover has a rim for engaging a formation at the upper surface of the base plate. A retention device is provided to retain the cover in position relative to the base plate.

Abstract: A valve for controlling flow of fluid through an aperture in a barrier comprises a valve body including a pin and having a continuous sealing surface surrounding at least one opening through the valve body, and a diaphragm of resilient material. The diaphragm has an opening surrounded by an inner margin and is disposed with the pin extending through the opening and with a main surface presented towards the continuous sealing surface of the valve body. The inner margin of the diaphragm is in a state of tension around the pin of the valve body, whereby the diaphragm is prestressed to a condition in which the main surface of the diaphragm engages the sealing surface of the valve body.