The Pneumatic System; Reducer; Gauge And Whistle; Demand Valve - Scott Contour User Instructions

CONTOUR
2.4 THE PNEUMATIC
SYSTEM
The pneumatic system has two pressure
reduction stages: air from the cylinder is
reduced to a medium-pressure (MP) of
between 5.5 and 11 bar by the reducer.
The second pressure
performed in the facemask Demand
Valve (DV).
Air from the cylinder passes through a
sintered bronze particle filter in the
cylinder connector, which protects the
pneumatic system, then through a short
length of High Pressure (HP) braided
hose to the reducer inlet manifold.
2.5

REDUCER

The reducer is a simple, self-regulating,
spring and piston device, which requires
no adjustment. It has a pressure relief
valve (PRV) that protects the MP system
from over-pressurisation.
Air from the reducer is connected through
a reinforced chlorinated polyethylene
hose to the facemask-mounted DV, which
regulates the air supplied to the wearer.
2.6

GAUGE AND WHISTLE

A high-pressure hose from the reducer
inlet manifold connects air, at cylinder
pressure, to a warning whistle and
pressure gauge mounted on the Contour
shoulder strap.
On standard versions, the warning whistle
and pressure gauge are mounted on the
left-hand shoulder strap.
reduction is
6
On versions fitted with the IRIS data-
communications system, the warning
whistle and pressure
incorporated within the IRIS unit.
The warning whistle
pressure in the cylinder falls to 55 bar (±5
bar).
The duration of the air remaining in the
cylinder, from the start of the warning
whistle, is listed for each cylinder type
under Warning Period in Table 3.
The pressure gauge
luminescent to aid use in low light levels.
The lens is
polycarbonate. A rubber shroud protects
the gauge.
Should the gauge, whistle or hose
become damaged, a restrictor in the
reducer limits air-loss to less than 25
litres per minute.
2.7

DEMAND VALVE

The DV operates in conjunction with the
facemask spring-loaded exhale valve to
maintain a positive pressure within the
facemask.
The DV has a servo-assisted tilting
diaphragm mechanism that responds to
pressure changes within the facemask to
regulate the flow of air to the mask,
ensuring that pressure within the mask
remains safely above ambient.
The DV has a reset button that enables
wearers to close the air-flow through the
DV, allowing the facemask to be removed
during test procedures and at the end of a
task without loss of cylinder air.
gauge are
sounds when
dial is photo
impact resistant