during exceeding of the limit of admissible explosion-safe concentration of HIL vapour
and power supply according to the first category of safety. In air pipes of the systems,
sewing the premises of A and B categories, the ventilation equipment is made as the
explosion – proof one. Regulating devices, gates, dampers in the exhaust systems must
be protected from sparks. The ventilators of the systems must be located on one axis
with an electric motor. The equipment of forced and exhaust systems for premises of
A and B categories is not allowed to be located on underground, basement and ground
floors. In the premises of A and B categories, the ventilation of grooves is carried out.
Near the premises of A and B categories, platform-sluices of the first type with
constant prop of the air are made. Air supply into platform-sluices is carried out with
the help of a separate system, which has a reserve ventilator with an electric motor,
which is turned on automatically when the main ventilator stops. In ventilating
chambers of the premises of A and B categories, the following things are foreseen:
– for the forced systems-forced ventilation with not less than twofold air-
exchange;
– for the exhaust systems-exhaust ventilation with single air-exchange.
On the air pipes, crossing protecting constructions of a ventilating chamber, fire-
inhibiting valves are foreseen. The shafts of the exhaust systems are designed without
torch cappings and umbrellas. The shafts of the natural exhaust are mounted on the
roofs of the buildings of A and B categories, can be used for removing smoke during
the fire.
In the premises of A, B and C categories, the remote centralized disconnecting of
all ventilation systems (except the systems of anti-smoke protection) in case of the fire
with the help of the devices, located outside the premises, according to the plan of
liquidation of the accidents. The systems of air delivery into platform-sluices aren’t
turned off in these situations.
It is allowed to locate forced ventilation units in one chamber, which work without
recirculating and serve the premises of different categories. In this case, on all forced
air pipes, self – closing reversible valves in explosion-protective design are mounted
by the exit from the ventilating chamber (within its limits). From the premises of A and
B categories, air recirculation isn’t allowed.
Air intake is provided for the systems of ventilation from the places, which
exclude getting of HIL into the system of ventilation. During simultaneous isolation of
HIL vapour heat and moisture, the amount of forced air should be taken greater, than
the received from the calculations for every type of production premises.
Ventilation forced units for the premises of productions of different categories
must be separate. It isn’t allowed to locate forced and exhaust units in one ventilation
chamber.
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