14
4.2.2 The elastic
sealer
(2) made from silicon rubber has the double obturator
(10) and five eyelets (one frontal eyelet (11), two temporal eyelets (12), and two cheek
eyelets (13).
The temporal and frontal eyelets have one hole and the cheek eyelets have two
holes to insert the buttons (8).
The double obturator assures secure hermetical sealing of the Mask on the
person’s head.
The sealer is attached to the visor by means of the upper (3) and lower (9)
housings, crewed to each other by two screws (14) with washers (15), and nuts (16).
4.2.3 The
valve
unit
(4) with an exhalation valve is assembled in the central hole
of the visor and is sealed by means of the O-ring (17) during the tightening of the
nut (18).
4.2.3.1 The exhalation valve, consisting of the exhalation valve leaf (19) and
exhalation valve seat with the membrane (20), serves to remove the air exhaled
by the person as well as to prevent from penetration of unpurified air from the
atmosphere.
The plastic membrane serves for voice communication and assures normal
speech intelligibility, including cases when the person gives commands or operates
communication means. The joint between the exhalation valve seat and the valve
unit body is sealed by the O-ring (21) during tightening of the meshed nut (22).
4.2.3.2 The plug (23) with the O-ring (24) is tightly inserted in the central hole of
the valve unit.
4.2.3.3 The cover plate (25) is put on the nut in order to cover the nut and the
valve unit joint on the exterior of the Mask and to provide a better appearance of
the item.
4.2.4 The
undermask
(5) consists of the undermask body and two inhalation
valves. The availability of the undermask in the Mask design prevents from sweating
of the visor and reduces carbon dioxide content in the inhaled air.
4.2.4.1 The body of the undermask made from silicon rubber, covers the person’s
mouth and nose and ensures cleaned air supply to the person’s respiratory system
through the inhalation valves. The obturator of the undermask body ensures the
required contact of the undermask and the face along the obturation line.
4.2.4.2 The inhalation valve on the undermask consists of the plastic seat (26) of
the valve and the inhalation valve leaf (27).
4.2.5 The
filter bayonet type coupling unit
(6) consists of the seat of the inhalation
valve with the bayonet (28) with the inhalation valve leaf (29), the nut (30) and the
O-ring (31). The joint between the visor and the seat of the inhalation valve with the
bayonet is sealed by means of the O-ring (32) during tightening of the nut (30).
4.2.6 The
head harness
(7) from silicon rubber serves to fix the Mask on the
person’s head. The head harness consists of the parietal part of the head harness
(33) and the straps molded in block with it: two temporal straps (34), two cheek
straps (35), one frontal strap (36), and five buckles (37).
The head harness straps are fixed to the Mask visor by means of the buckles (37)
and buttons (8).
Each strap has a scalloped surface to assure secure fixture of the straps in the
buckles and each strap has a widened end serving as a restraint.
