A pressure regulator assembly for a facemask of a self-contained breathing apparatus, the pressure regulator assembly comprising: a housing defining a first chamber in fluid communication with an inlet and a second chamber in fluid communication with an outlet; a valve assembly disposed between the first chamber and the second chamber; and a bypass assembly connected to the housing and operatively engaged with the valve assembly, the bypass assembly comprising a bypass housing and a bypass knob, the bypass knob comprising: a first member having a first engagement surface; a second member having a second engagement surface positioned opposite the first engagement surface; at least one slot on the first engagement surface of the first member; and at least one deflectable beam on the second engagement surface of the second member, wherein the at least one deflectable beam has a first end connected to the second member and a second, free end opposite the first end, wherein the second end has a latch protruding from the second engagement surface such that the latch is receivable within the at least one slot, wherein the latch has an angled surface that is angled in a direction from the second end toward the first end wherein the first member and the second member are configured for rotating about a first axis, wherein, when the first member is rotated in a first direction about the first axis via a first rotational torque, the latch of the at least one deflectable beam is engaged with the at least one slot to rotate the second member with the first member, and wherein, when the first member is rotated in the first direction via a second rotational torque higher than the first rotational torque, the second end of the at least one deflectable beam is deflected from a first, undeflected position to a second deflected position whereby the latch is disengaged from the at least one slot such that the first member rotates relative to the second member. a housing defining a first chamber in fluid communication with an inlet and a second chamber in fluid communication with an outlet; a valve assembly disposed between the first chamber and the second chamber; and a bypass assembly connected to the housing and operatively engaged with the valve assembly, the bypass assembly comprising a bypass housing and a bypass knob, the bypass knob comprising: a first member having a first engagement surface; a second member having a second engagement surface positioned opposite the first engagement surface; at least one slot on the first engagement surface of the first member; and at least one deflectable beam on the second engagement surface of the second member, wherein the at least one deflectable beam has a first end connected to the second member and a second, free end opposite the first end, wherein the second end has a latch protruding from the second engagement surface such that the latch is receivable within the at least one slot, wherein the latch has an angled surface that is angled in a direction from the second end toward the first end wherein the first member and the second member are configured for rotating about a first axis, wherein, when the first member is rotated in a first direction about the first axis via a first rotational torque, the latch of the at least one deflectable beam is engaged with the at least one slot to rotate the second member with the first member, and wherein, when the first member is rotated in the first direction via a second rotational torque higher than the first rotational torque, the second end of the at least one deflectable beam is deflected from a first, undeflected position to a second deflected position whereby the latch is disengaged from the at least one slot such that the first member rotates relative to the second member. a first member having a first engagement surface; a second member having a second engagement surface positioned opposite the first engagement surface; at least one slot on the first engagement surface of the first member; and at least one deflectable beam on the second engagement surface of the second member, wherein the at least one deflectable beam has a first end connected to the second member and a second, free end opposite the first end, wherein the second end has a latch protruding from the second engagement surface such that the latch is receivable within the at least one slot, wherein the latch has an angled surface that is angled in a direction from the second end toward the first end wherein the first member and the second member are configured for rotating about a first axis, wherein, when the first member is rotated in a first direction about the first axis via a first rotational torque, the latch of the at least one deflectable beam is engaged with the at least one slot to rotate the second member with the first member, and wherein, when the first member is rotated in the first direction via a second rotational torque higher than the first rotational torque, the second end of the at least one deflectable beam is deflected from a first, undeflected position to a second deflected position whereby the latch is disengaged from the at least one slot such that the first member rotates relative to the second member.