Innovations
OHD Patents
As an innovator in respirator fit testing solutions, OHD is proud to hold the patents on the technologies and products below.

Controlled Negative Pressure
Patent Number US 8,528,559, B2
Issued Date of Patent: September 10, 2013
Description: For fit testing of a respirator positioned on a test subject’s face and connected to a controlled negative pressure testing apparatus, the test subject simply holds his breath and then activates a switch in electrical connection with said apparatus, which results in the automatic closure of the breathing port on the respirator and the initiation of a complete fit-testing protocol. The fit-testing apparatus includes a single, self-contained, automated unit that includes a vacuum source, an air-flow measuring device, and an air-pressure transducer for connection to a respirator being tested. By measuring the rate of air exhausted from the respirator in order to maintain a constant challenge pressure, an air leakage rate is determined.
Relevant Products: QuantiFit2, QuantiFit2 Virtual Operator
QuantiFit2 Virtual Operator
Patent Number US 12,023,529 B1
Issue Date of Patent: July 2, 2024
Description: A system, method, and computer program product for performing a respirator fit test. An example aspect is configured to instruct a user to select a respirator; instruct the user to connect at least one set of tubing to the respirator and a fit testing device; instruct the user to don the respirator; prompt the user to begin the respirator fit test; perform the respirator fit test upon receiving a positive response from the user; detect, at a processor, a signal from the respirator fit testing device; analyze data of the respirator fit test on the processor; troubleshoot at least one failure of the respirator fit test when a failing fit factor is detected; display to the user a subset of videos on a graphical user interface to correct the failure; and perform the respirator fit test at least a second time.
Relevant Products: QuantiFit2 Virtual Operator


Patent Pending Innovations
AeroFit and Components
Silent Operation
Particle Generation Management
Convertible Adapters