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Air streams are mixed to save energy and improve energy efficiency by partially recirculating conditioned air.. The most common application for an air-mixing plenum is the mixing of return air (or extract air) with fresh air to provide a supply air mixture for onward distribution to the building or area which the ventilation system is serving. [1]
The term "plenum" was coined in the 1670s, derived from Latin adjective plenus ("filled, full"). The usage originates from classical theories of physics and the notion that "nature abhors a vacuum". These gave rise to the notion of 17th century 'plenum' as the opposite of vacuum, and all things "being either Plenum or Vacuum". [2]
This damper can switch the electrical power to control additional "slave" dampers, minimizing the electrical load on the damper's control circuitry and power transformer. A zone damper (also known as a Volume Control Damper or VCD) is a specific type of damper used to control the flow of air in an HVAC heating or cooling system. In order to ...
The Zelinsky-Kummant gas mask was the world's first gas mask [1] which had the ability to absorb a wide range of chemical warfare agents. The gas mask was developed in 1915 by Russian chemist Nikolay Zelinsky and technologist of the Triangle plant M.I. Kummant. [2] The design was later improved by I. D. Avalov and entered mass production.
A register's damper provides a critical function. Primarily, the damper allows the amount of hot or cool air entering a room to be controlled, providing for more accurate control over room temperature. [7] Dampers also allow air to be shut off in unused rooms, improving the efficiency of the HVAC system.
A gas spring consists of a sealed cylinder filled with a charge of high-pressure [5] gas, a piston rod attached to a piston with a sliding seal, and some oil. [1] The piston (or the cylinder wall) contains a number of channels that allow the gas to transfer between the lower chamber (between the piston and the closed end of the cylinder) and the upper chamber (between the piston and the head ...
A World War I British P Helmet, c. 1915 Zelinsky–Kummant protivogaz, designed in 1915, was one of the first modern-type full-head protection gas masks with a detachable filter and eyelet glasses, shown here worn by U.S. Army soldier (USAWC photo) Indian muleteers and mule wearing gas masks, France, February 21, 1940 A Polish SzM-41M KF gas mask, used from the 1950s through to the 1980s
Most commonly, VAV boxes are pressure independent, meaning the VAV box uses controls to deliver a constant flow rate regardless of variations in system pressures experienced at the VAV inlet. [2] This is accomplished by an airflow sensor that is placed at the VAV inlet which opens or closes the damper within the VAV box to adjust the airflow. [2]