INGRESS PROTECTION & MEDICAL CABLES
It is often desirable and sometimes necessary to require protection against the intrusion of foreign objects, dust, or water into medical devices, including medical cables and connectors. A method to clarify degrees of protection is provided by the International Electrotechnical Commission (IEC) standard 60529. Titled “Degrees of protection provided by enclosures,” it is commonly referred to as the Ingress Protection or “IP” Code.
Ingress protection for medical cables is most often thought to mean protection against ingress of water or moisture. While moisture protection is one of the levels of ingress protection, keeping solid objects, such as a finger or tool, out of a device or connector is a significant part of the standard.
IEC 60529
IEC 60529, second edition is but one of many standards adopted by the International Electrotechnical Commission. This standard defines degrees of ingress protection for enclosures including:
- Protection of persons against access to hazardous parts inside the enclosure
- Protection of the equipment inside the enclosure against ingress of solid foreign objects
- Protection of the equipment inside the enclosure against harmful effects due to the ingress of water
The standard offers designations for these degrees of protection, requirements for each designation and tests to be performed to confirm that the enclosure meets the requirements of the standard.
IEC 60529 only addresses ingress and is therefore often used in conjunction with NEMA 250 when it relates to enclosures. It is also important to understand that IEC 60529 specifically addresses “harmful” ingress, whether it is by a solid or liquid.
INGRESS PROTECTION RATINGS
The Ingress Protection Rating is more commonly referred to as the IP code. The IP code as defined in IEC 60529 pertains to the broad category of electrical enclosures. An electrical enclosure may be an electric or electronic device, an electrical component, or as related to products that ClearPath Medical manufactures, a medical connector or medical cable assembly. The IP code should not be confused with the term IP address, used in data communications or IP as in Intellectual Property.
IP ratings are generally presented as two digits; the first digit refers to protection against ingress by solid objects and the second digit refers to protection against ingress by moisture or water.
For protection against solid objects level 2 is designed to prevent fingers or similar sized objects from accidentally touching hazardous components, such as electrical contacts. Level 4 protection prevents contact by objects 1mm or greater and is often referred to as “tool-proof.” Levels 5 and 6 offer dust protection, and level 6 provides complete protection against solid objects such as fine dust.
The second digit of the IP rating refers to protection of the device against harmful ingress of water or moisture. Level 4 protection will prevent water splashed onto the enclosure from any direction from causing harm. A device with level 4 water protection should withstand cleaning with liquids except for submersion. It is important to understand that an IP rating does not indicate materials are able to withstand various cleaning solutions; only that moisture from those solutions will not enter the device in an amount to be harmful.
INGRESS PROTECTION RATING CODE TABLE
ACHIEVING INGRESS PROTECTION FOR LIQUIDS
Protection against harmful ingress by liquids or moisture is not difficult to achieve when addressed early in the design stage. Protection is commonly achieved by molding thermoplastic material over other components. When done properly, a high level of ingress protection is achieved without adding cost to the product.
Many medical connectors consist of insulators with pins or sockets inserted into hard plastic. When overmolded with common thermoplastic materials, the assembly achieves a high degree of protection against harmful ingress by liquids. Providing the same degree of ingress protection when mated to another connector requires additional engineering and design considerations.
A common method to achieve a high degree of ingress protection between two connectors is for one side to be made of a hard material and the opposite side to be made of a softer material. The size and geometry of the softer material is designed so that it must be stretched over the mating component providing a seal against moisture ingress.
To achieve a tight, waterproof fit, tooling is designed so that when first fabricated the fit of one component over the other is too loose, offering little ingress protection. This tool-safe method requires subsequent machining to remove material from the mold for the outer component. Each time material is removed from the tool, the fit of the molded part becomes tighter until the desired feel and level of ingress protection is achieved.
To achieve an IPX6 to IPX8 rating and maintain reasonable mate and un-mate force, elastomeric ribs designed to fit into grooves in the receptacle are often employed.
SUMMARY
The need for ingress protection for medical cables and the level of protection desired or required are elements that should be addressed early in the design phase of medical connectors or cable assemblies. ClearPath Medical has experience and expertise in designing and manufacturing devices which meet our OEM partner’s ingress protection requirements. If you would like to discuss ingress protection and how it relates to your cable or connector project, contact the ClearPath Medical engineering team.
Contact us and learn more about how we can improve the life, function, and look of your finished medical cable assembly.
