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Means for Retaining Elastic Strap to Half Mask Respirator

IP.com Disclosure Number: IPCOM000248016D
Publication Date: 2016-Oct-18
Document File: 4 page(s) / 282K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method to attach and retain an elastic strap to a face-piece respirator device using simple but effective means. In this example, the attached strap is to retain up to 50 newton (11lb) of pull force for use as an attachment to half mask respirator. The method uses a fold-over strap that is sonically welded (or bonded, or stapled) and then threaded through an appropriately sized slot to achieve attachment and retention.

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Page 01 of 4

Means for Retaining Elastic Strap to Half Mask Respirator Abstract:

A method to attach and retain an elastic strap to a face-piece respirator device using simple but effective means. In this example, the attached strap is to retain up to 50 newton (11lb) of pull force for use as an attachment to half mask respirator. The method uses a fold-over strap that is sonically welded (or bonded, or stapled) and then threaded through an appropriately sized slot to achieve attachment and retention.

Detailed Description:

Initially the strap material is cut to length and either sonically welded, bonded, or stapled on end as shown. The strength of the weld / bond is determined by the requirements and materials of the application, e.g., a ½" wide strap with a thickness of .055" consisting of polyester blended elastic material sonically welded with a weld length of approximately ¼" will achieve a desired retention of 50 newton of tension. The free length (or tab) of the welded end provides retention for the attachment by doubling the thickness of the strap. To be effective, the free length should be approximately 4 times the thickness of the strap (or greater) as determined by experience during initial testing.

(or Stapled)

Fig. 1


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The slot size opening (thickness), wall thickness and flexural modulus of the slot material are also directly related to the amount of strap retention. (See Fig. 2 and "Retention Test") For a half mask using a high impact nylon 6/6 an optimized thickness of 1.25 times the un-tensioned strap thickness (.055") is used.

To provide options for the application, the width of the slot may be adjusted to create a slight clearance or slight interference between strap and slot. Providing clearance (slot wider than strap) allows for easier assembly. Conversely, creating a slight interference (slot width less than strap) allows strap to be retained to slot without tension. (This may require the strap to be tensioned during assembly to allow threading through slot.) Initial testing showed that slight clearance or interference has a small effect on the amount of strap pull force retention. Overall slot length has a larger effect. (See Fig. 2 and "Retention Test")

The strap is easily i...