Enclosure Selection Guide

Author: Nigel Rowland   Date Posted:15 February 2016 

Enclosures house and protect electronic and electrical components from the environment or from accidental contact. With an almost limitless variety of enclosures to choose from, this article will help guide you in the selection process to find the right enclosure for your application. Here are a few things you will need to consider.

What kind of environment does your enclosure need to withstand?

This is the most important question and will determine the longevity of your enclosure. Is there rain, salt water, and dust or wind storms. This will determine the IP Rating for the enclosure.

 IP Rating (First Number)

 Degree of protection  against solids

 IP Rating (Second  Number)

 Degree of protection  against water.

  0

 No special protection

  0

 No Protection

  1

 Protected against solid  objects over 50 mm, e.g.  accidental touch by  person’s hands.

  1

 Protection against  vertically falling drops of  water. E.g. Condensation

  2

 Protected against solid  objects over 12 mm, e.g.  persons fingers

  2

 Protection against direct  sprays of water up to 15  degrees from the vertical

  3

 Protected against solid  objects over 2.5 mm  (tools and wires).

  3

 Protected against direct  sprays of water up to 60  degrees from the  vertical.

  4

 Protected against solid  objects over 1 mm  (tools, wires, and small  wires).

  4

 Protection against water  sprayed from all  directions – limited  ingress permitted.

  5

 Protected against dust  limited ingress (no  harmful deposit).

  5

 Protection from water  sprayed from all  directions – limited  ingress

  6

 Totally protected against  dust.

  6

 Protected against  temporary flooding of  water. E.g. for use on  ship decks. Limited  ingress permitted.

 

 

  7

 Protected against the  effects of immersion  between 15cm and 1  metre

 

 

  8

 Protects against long  periods of immersion  under pressure.

 

The environment will also determine what material the enclosure needs to be. 304 and 316 Stainless Steel enclosures are ideal for harsh applications due to their corrosion resistance. 316 stainless steel will be more resistant to chlorine and salts so it is the best suited for marine applications. More cost effective solutions are GRP and Polycarbonate enclosures. They have a high strength to weight ratio and are much easier to modify in the field than their steel counterparts.

Figure out the size of the enclosure that fits your application.

 First you need to find out the length, width, and height of your project with all the components when mounted on a back panel. With that, you now have your minimum internal dimensions of the enclosure. You can size up accordingly if heat dissipation is a factor or if there will be controls mounted onto the cover of the enclosure. Lastly, if the enclosure is fitting into an existing footprint make sure to double check external dimensions.

 Does it need Thermal Management?

Heat naturally dissipates from enclosures but in many cases natural cooling or heating is not enough for an application. Steel enclosures conduct heat to bring the internal temperature closer to the ambient outside temperature while polycarbonate/fiberglass enclosures insulate the internal temperature. This may not always suit your components’ temperature requirements. Thus, thermal management must be considered since overheating/freezing will damage or shorten the life of your devices. Vent kits, exhaust fans, and air conditioners can be used in conjunction with thermostats to regulate heat. Heaters and hygrostats can also be used to control condensation in damp environments.

Do you plan on doing any modifications to the enclosure?

GRP and polycarbonate enclosure are the easiest to work with if holes are required and don’t require sealing on the cut edge. This is ideal if any cutting or drilling needs to take place on site.

Stainless steel needs special consideration when cutting due to the hardness of the metal, and preferably any cutting would be done by water jet cutter. If it is welded or cut using a grinder or Drill the surfaces will need to be treated or ‘pickled to remove the heat tinted layers from the surface where the steel’s surface chromium levels have been reduced.

Carbon Steel or mild steel enclosures are more easily cut and welded than stainless steel however cut edges and surfaces will needed to be painted to prevent corrosion.

Advantages and Applications.

Metal Enclosures

Advantages & Applications:

Carbon Steel: Cost effective solution for general indoor and outdoor use where corrosion is not an issue.

Stainless Steel (304 & 316): Known for tough, corrosion resistant construction. Ideally suited for food processing areas, dairies, breweries or any wet areas (marine environments). Also works well where caustic elements or alkalis are present.

Polycarbonate Enclosures.

Advantages: Very high impact rating, easy to modify, light weight, and high gloss finish. Applications: Due to its advantages, it can be used in many automotive, aircraft, industrial, and electrical applications. Also recommended for wireless applications (Does not block radio waves).

GRP Enclosures

Advantages: Good rigidity, chemical resistance, wide temperature range, and electrical properties. Applications: Indoor or outdoor use where environments of extreme temperature, high salt concentration, strong alkalis, acids or organic solvents are present. Also, recommended for continuously wet environments and wireless applications (Does not block radio waves).


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