Environmental Recommendations for Computer Areas
This document is substantially out of date, although many of its recommendations are still relevant.
This document provides recommendations for the provision of a suitable environment both for users of computers and the computers themselves.
Further documents of particular relevance to computer users are maintained by the CUED Safety Office .
Although some of the recommendations in this document are usefully applicable to offices containing a single computer, they are aimed particularly at areas containing two or more computers. They are particularly concerned with computers that are in continuous use (where job processing occurs unattended).
In order to avoid significant component failure rates, which
result in lost work, unavailability of equipment, and wasted time
spent in repairs, quite apart from financial cost, computers need
to be maintained, as far as possible, in an environment at
constant temperature .
It is a fallacy to assume that this temperature need be very low: the recommendation of this document is that the temperature in a room containing computing equipment should be maintained as consistently as possible at some point in the range 21-24 degrees centigrade.
It is also a fallacy to assume that, since this temperature is not particularly cold, comparatively low-powered air-conditioning units can be got away with. If there is a lot of computing equipment in an area, it will require a powerful air-conditioning unit to maintain the temperature consistently even at 20 or 25 degrees centigrade.
Humidity is of rather less concern, unless there are other
activities or equipment in the area that are likely to raise the
humidity significantly. In general, air conditioning
units capable of maintaining satisfactory temperature levels will
have no problem with the task of maintaining humidity. Air
cooling units, however, will not control humidity, which may
cause long term damage to computing equipment.
Regular maintenance of air conditioning units is necessary to ensure that drainage pipes are not blocked, as they can generate surprisingly large quantities of water at certain times of year.
- 24 hour environmental control
It is not the case that environmental control need
only be an issue during "normal working hours". Most modern
computer systems either need to be, or work best when, left
powered and working all the time. Experience has shown that the
temperature in areas containing computing equipment can reach
dangerously high levels (upwards of 40 degrees centigrade) in the
absence of air conditioning overnight.
One of the most effective ways of causing damage to computing equipment in the long term is to regularly change the environmental temperature over a significant range. It is therefore very important that air conditioning units be run 24 hours a day.
- Vibration and Knocks
Although often difficult to ensure, ideally computing equipment
should be placed on a solid surface, and if on the ground should
be somewhere where peoples' feet are unlikely to kick. Tables
with computing equipment on should either be attached to a solid
wall, or out of the way of main access routes.
- Power supply
Power cords (and indeed other computer cables) should be kept out
of reach of kicking/tapping/fidgeting feet. Cable ties are useful
although sometimes irritating when access is required to
a piece of equipment.
- Dust, dirt and general equipment maintenance
- Keyboards, screens, mice
- Inside equipment
It is probably not sensible to regularly open up equipment for
cleaning. However, when opened anyway, it is well worth
vacuuming carefully around if large amounts of dust are visible.
This is particularly the case in CUED, where the quantities of dirt and dust created by the more experimentally oriented parts of the department have a very determined tendency to get sucked into computing equipment.
External disk drives in particular should be checked regularly to ensure that fans are still working. A failing fan can easily be detected - the disk case will be hot to the touch.
Unusual sounds from your computer may well be (but are not necessarily) an indication of the failure of an internal fan. Some modern computers will shut themselves down (Sun and SGI) or produce an audible warning (some x86/pentium motherboards) when overheating. All recent pentium processors with attached fans, and all models of Sun Ultra1 workstation are vulnerable to stuck cpu fans. Recent HP workstations can also collect large enough amounts of dust in their cpu fan units to cause intermittent failures.
Similarly, dust will frequently collect in large amounts
around the back of computing equipment - ideally this should
be regularly cleaned away.
Furthermore, the surroundings of computing equipment should be kept tidy, with particular attention to keeping air intakes and outlets clear of blockage .
- Keyboards, screens, mice