Glass door racks are a type of rack that have solid glass front doors and rear door heat exchangers (RDHx). RDHx are devices that use facility coolant to absorb heat from the exhaust air of the IT equipment and return cool air to the room. RDHx can be either passive or active, depending on the fan configuration. In general, IT hardware within the rack is air-cooled and the door heat exchanger uses facility coolant to absorb heat from exhaust air to return air to the facility at or near inlet air temperature to the rack. This rear door heat exchanger can either be a passive or active solution. When dealing with glass door racks, cool air is injected into the rack from the rear door in a downflow direction. This means that the cool air flows from the top to the bottom of the rack, following the natural convection of the hot air rising. This way, the cool air can reach all the IT equipment in the rack and prevent hot spots or overheating.
[References: [SOLVED] Rack - Solid or Mesh front door? - Data Center IT](https://community.spiceworks.com/topic/510677-rack-solid-or-mesh-front-door), ChilledDoor, Rear Door Heat Exchanger | Data Center Cooling, ACS Door Heat Exchanger Requirements for Open Rack., , ]
Question 25
Which type of Humidifier suspends quartz lamps over an open pool of water?
Infrared humidifiers are a type of humidifier that use quartz lamps to heat water in an open pool and evaporate it into the air. They are energy-intensive and require frequent maintenance and cleaning. They are not recommended for data centers, as they can introduce contaminants and bacteria into the air, and increase the risk of fire and electrical hazards.
[References: EPI Data Centre Training Framework, CDCP Preparation Guide, Make Humidification Adjustments | ENERGY STAR, , , , ]
Question 26
Where should exit/emergency signs be located?
Options:
A.
Depends on the policy of the data centre
B.
At every escape door and pathways leading to doors (arrows)
According to the EPI Data Centre Operations Standard (DCOS), exit/emergency signs should be located at every escape door and pathways leading to doors (arrows) to ensure a safe and quick evacuation in case of an emergency1. This is also consistent with the best practices for data centre emergency preparedness and response, which recommend having a clear and visible signage system for emergency exits23.
[References: 1: EPI Data Centre Operations Standard (DCOS), Version 2.0, Section 5.4.2.1, Page 42 2: How to Prepare and Respond to Data Center Emergencies, White Paper 217, Schneider Electric, Page 4 3: How to Properly Manage Data Center Emergencies, IT Business Edge, Slide 2, , ]
