IP letters are the abbreviation to Ingress Protection. It is an international standard code that shows how well a product (or device) is protected from solid and liquid entering its casing or enclosure. It is regulated by the International Electrotechnical Commission (under IEC 60529).

It usually comes with two digits. The first one related to the solid particles ingress protection, and the second one refers to liquids ingestion. According to the definition, IP67 means that the product is:

• Dust-tight (6): no dust ingress will happen
• iquid protection (7): able to be immersed 1 meter deep in water for 30 minutes and still continue working (water can get in, but not in sufficient quantity as to cause functional problems)

Some design guidelines for IP67 are:

• Product enclosure should be properly sealed from outside to avoid dust ingestion and water ingress when immersed. This can be achieved by using:
  • Static o-rings for lids or circular components that doesn't move once installed
  • Dynamic o-rings for parts that need to move under water (like for instance motor shafts)
  • Custom seals and gaskets to seal two faces with irregular shaped
• Select connectors and cables rated for IP67 (if needed)
• Sealed buttons: usually made of rubber, but rigid materials can also be used together with external sealing to the enclosure