Care in choosing a suitably rugged computing platform, be it a Notebook, Tablet or portable "lunch-box" Chassis, is crucial where it is envisaged the system is to be used outside the relatively benign environment of the office. A set of ratings have been produced to fix some definable standards so that a judgement can be made as to the suitability of a particular computer system to a task and are most commonly are defined in two forms:-

1. MIL (military) STD 810E/F testing protocols for resistance to rain, humidity, salt fog, sand/dust, vibration, shock and temperature.
   
   
2. IP (Ingress Protection) testing which establishes the ability of an electrical enclosure to withstand penetration from solids (sand/dust) and liquids.

The military standard MIL 810E and F (F superseded E in January 2000) is a broad range of testing protocols but from which is selected the most relevant to match the environmental challenges for a particular piece of equipment. The broadness of choice does make it difficult to place in a nutshell all the various aspects of this stringent standard, but as an example we can concentrate on the its most relevant application to portable rugged PC's; that is the drop test. The MIL-STD 810E/F specification for mechanical shock calls for portable computers such as tablet or notebook PC's to withstand 26 drops, (one drop on each face/edge/corner with display screen closed, and unit powered off), onto 2" thick plywood over solid concrete from a height of metre - without functional failure. A computer successfully completing such a test is certified as MIL-STD 810E/F compliant in this respect.

In the real world this set of circumstances will be unlikely to be repeated, but it does give a good indicator as to the suitability and likelihood of survival, after all many off-the shelf high street computer systems can barely survive the general knocks in the office, let alone any kind of drop. Possessing a PC system with a MIL specification also means that physically the system should have a longer life. A high resilience to vibration is frequently another testing protocol applied, as in real life portable PC's can be used inside and alongside machinery or a vehicle.

IP rating describes the ability of an electrical enclosure to withstand penetration from solids and liquids, in real life most commonly dust and rain water. With electronic equipment choosing a suitable IP level is a critical factor. Below is a table that defines the levels. The first digit indicates the level of protection that the enclosure provides against access to hazardous parts/particles, the second harmful ingress of water. So for example IP67 gives complete protection from all solid particulates (6) and withstand temporary water immersion to 1 metre (7).

If the PC system is to be used where there is any risk of liquid or dust contamination then choosing a system with a rating of at least IP54 is advisable. Such a rating will allow its use outdoors in the field environment, repelling rain water and wind borne dust to a high degree. However where it is envisaged the system is to be used for several hours in heavy blowing rain or on the exterior deck of a ship a higher IP65 or 67 level should be considered.

We trust the information above has been interesting and useful.