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CONVEYOR BELTS PART- 2 SAFETY DEVICES

 









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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