May 15, 2019 / Douglas Durney

Is a Hooded PAPR Right for Your Organization?

Sponsored by ILC Dover

Full-face respirators with either single or dual cartridges have long been used by the military and first responders to protect against the most hazardous of toxic respiratory threats, including nerve and blister agents. They offer the benefits of portability and relatively compact size, and they also facilitate weapons sighting. In the industrial setting, full-face respirators with dual cartridges are also compact and relatively easy to use, but they have some disadvantages when compared to powered-air loose-fitting hoods.

Full-face respirators, elastomeric half masks, and filtering facepieces all rely on the wearer’s inhalation creating a negative pressure in the internal mask cavity to draw contaminated air through the filters. When used properly and in the proper environment, the filters remove the contaminant and provide the wearer with clean, filtered air. However, this negative pressure requires the mask or filtering facepiece to seal effectively to the face (or around the nose and mouth in the case of a half mask or filtering facepiece) to preclude the ingress of chemicals or particulates through the sealing area. The wide range of facial sizes and contours presents quite a challenge for the mask seal. To verify the seal integrity, OSHA requires fit-testing for these types of masks​.

As highlighted in 29 CFR Part 1910.134, fit-testing is not only required, it’s mandated on the exact model and size of the respirator that will be used. This requirement, coupled with the need to maintain records for these tests, can become quite onerous.

As noted earlier, on a negative-pressure facepiece respirator, the seal against the face serves as the primary barrier to contaminant entry upon inhalation. To ensure this barrier performs as designed, 29 CFR 1910.134 provides specific guidance on “facepiece seal protection.” Under this guidance, tight-fitting respirators are not to be worn by employees who possess facial hair that may interfere with the seal or employees who are required to wear glasses or goggles that would interfere with the seal.

An alternative respiratory protection system that eliminates many of these issues and provides enhanced overall protection (with the proper manufacturer test data backup) is the hooded PAPR (download a chart of the major types of respirators). With this class of respirator, the wearer is not pulling the outside air into the hood during inhalation. This function is performed by the PAPR motor/blower assembly. These devices draw the outside air through the attached filters into the blower chamber and then deliver a minimum of 170 liters per minute (6 cubic feet per minute) to the hood. In this situation, the employee is operating in a positive pressure environment in which the air is flowing from the clean inside environment of the hood out to the contaminated atmosphere. As a result, fit-testing is not required on this form of respiratory protection. In addition, for many hoods a single size can fit a wide range of users, and employees can retain their facial hair and normal glasses without compromising protection. In addition, since annual fit-testing is not required, recordkeeping is also reduced.

Of course, there are trade-offs. For hooded PAPRs, the head-borne weight is usually very low; however, there is weight associated with the blower and battery. These assemblies are typically worn on a belt or ergonomic back harness depending on the application. The filters reside with the blower so they don’t sit on the wearer’s face. Batteries require a routine charging protocol, and a flow check must be conducted prior to entering a contaminated area.

Depending on your application, a hooded PAPR system may be worth considering.

Douglas Durney

Douglas Durney is the product line manager for ILC Dover’s Protective Equipment Group. He has been involved in new product design/development and sales and marketing of protective equipment and other customer-driven engineered solutions for over 30 years. ​


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