CONVEYOR
BELT- SAFETY DEVICES
Safety device means a
type of safeguard consisting of an arrangement of operating controls which
ensures that a worker cannot access or be in a hazardous area while a machine
is operating.
SAFETY GUARDS:
Safety
guard means a type of safeguard consisting of a physical barrier which prevents
a worker from reaching over, under, around or through the barrier to a moving
part or point of operation.
The
following photos are an indication of such guards.
PULL SWITCHES:
The
pull wire is pulled to trip the conveyer. It must only be pulled for
emergencies and not to stop the belt. If the conveyor belt suddenly trips do
not start the belt, communicate with the control room operator and the belt
foreman, inspect the area and confirm with all before resetting a pull switch.
If you
are unsure request assistance from the supervisor and control room.
DO NOT TRY AND START THE BELT.
BELT ARRESTOR:
They
are usually installed on incline sections. They are there for the protection of
the workers and to minimize standing time when conveyor belt tears.
The
belt arrestor catches the belt when the belt starts to slide down to the bottom
of the conveyor belt system.
(Belt arrestor on surface)
(Belt arrestor Underground)
BELT ALIGNING LIMIT SWITCH:
This switch will trip the belt if the belt
starts to run off center.
BELT RIP PROTECTION:
If the
belt is ripped by a piece of metal the switch will be activated and the belt
will trip immediately
NIP
GUARDS:
All
pulleys must be guarded properly to prevent any part of a person’s body or limb
from coming into contact with the pulley.
The
minimum distance for access to the nip point is 900mm. The danger point is at
the converging angle, the “nip angle” between the belt and pulley, as it is at
this point that a human limb can be dragged in.
HOLD
BACK DEVICE:
All incline belts
must be fitted with a holdback device to prevent backward movement of the belt.
A loaded incline belt will tend to run backward when stopped.
FIRE
HYDRO SYSTEM:
Fire
hydro systems are installed over the whole length of the conveyor system.
Any
fire can be extinguished by means of this system.
EMERGENCY
STOP:
Another
device that can be installed is the manual emergency-tripping device as seen
below.
This
device is connected in series with the tripping wire safety system.
WARNING
BELL OR SIREN:
Siren or warning
bells are situated so as to warn persons of the subsequent starting-up of the
conveyor belt. These sirens or warning bells are connected to operate for a set
period immediately prior to the belt start-up.
LOCK
OUT SYSTEM:
a) The
lockout systems on conveyor belts are used whenever work is to be performed on
the conveyor belt.
b) This
system consists of a mechanical locking device (i.e., a lock) attached to a lock
out caliper on the start button or lever. The person working on the conveyor
must keep the key to the lock.
c) Before
any work is done on a conveyor belt the belt must be locked out.
Regulation No. 20.9.3.1 (South Africa)
“When any work or repairs are undertaken on any
machinery the person in immediate charge of such work or repairs shall ensure
that the power supply to such machinery is switched off or disconnected and
remains switched off or disconnected until the work or repairs have been
completed.”
INTERLOCKING
SYSTEM:
a) At a
mine where ore is transferred from underground to a plant or storage silos, a
number of conveyor belts are used, in order for this operation to run
effectively, efficiently and safely interlocking devices are installed on these
belts.
b) An
interlocking device is an electrical device designed to allow conveyor belts to
operate sequentially, meaning that one belt cannot or must not start without
the other belt running. These devices are used when one belt tips onto another
therefore if the belt that you are tipping on is not running the device will
stop the tip belt (strike belt) from starting up, this eliminates fault start
up or overloading of the conveyor belts.
CHAPTER 8 OF THE MHSA
REGULATIONS REGARDING MACHINERY & EQUIPMENT:
GENERAL
MACHINERY REGULATIONS:
8.8(1)
The employer must take reasonably practicable measures to prevent persons
from being injured as a result of them,
the clothes being worn by them or any equipment being held by them coming into
contact with or being drawn into any moving part of any machine.
8.8(2)
The employer must take reasonably practicable measures to prevent persons from
being injured because of any machinery failing as a result of-
(a) Incorrect design;
(b) Incorrect installation;
(c) Poor maintenance; or
(d) Incorrect use or non-compliance with proper
operating or safety procedures.
8.8(3) The measures to be taken by the employer in
terms of regulation 1 must include measures to ensure that-
(a) Only persons authorized by the employer to do so,
start operate and maintain any machine where such starting, operation or
maintenance may pose a significant risk to any person;
(b) Where the moving of machinery may pose a
significant risk to any person, such machinery is only moved under the constant
supervision of a competent person who is fully aware of the risks attached to
such moving of the machinery;
(c) Only persons authorised by the employer to do so
enter any area where machinery is operated, where such operation may pose a
significant risk to any person;
(d) Machinery is only operated if all installed safety
devices are operational and functional;
(e) Persons in close proximity to moving parts of
machinery do not wear or are not permitted to wear clothing or anything else
that can be caught in such moving parts;
(f) Where the unexpected moving of any machinery or
any part of any machinery could pose a significant risk to any person,
appropriate prestart warning devices, such as audible warning devices, the
delay time must be determined by risk assessment with a minimum of a ten second
time delay, are fitted to such machinery and used to warn persons that such
machinery is about to be set in motion;
(g) Where there could be a significant risk to any
person working on any machinery due to the release from such machine of any
mechanical, electrical, hydraulic, chemical or other source of energy, a
written lockout procedure is prepared and implemented to ensure that such
source of energy is effectively locked out and de-energised before any person
works on such machinery;
(h) Access scaffolding is erected, used, maintained
and dismantled safely and in accordance with SANS Standard 10085-1:2004
"The design, erection, use and inspection of access scaffolding".
(i) Means are provided, on or in close proximity to
any machine, to immediately remove the source of power to that machine in case
of an emergency;
(j) Where the starting of machines are interlocked, no
unintended starting of any of those machines can take place;
(k) Starting devices are so arranged that no
accidental starting of machinery can take place; and
(l) All electrical, pneumatic and hydraulic portable
equipment are operated and maintained in a safe working order;
8.8(4) The measures to be taken by the employer to
prevent any person from coming into
contact with any moving part of machinery or any equipment attached
there to, must include-
(a) Effective physical barriers at the machinery such
as screening, guarding or fencing; or
(b) Failsafe electric or electronic barriers
interlocked with the machinery in such a way that the machinery would be
stopped before persons come into contact with moving machinery or parts
thereof; or
(c) Effective barriers at a safe distance away from
any machinery.
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