Dear Mr. Mahesh,

GOOD YEAR Co,can supply belt with sensor embeded to it for detection of any tear in the belt.You may contact to them.

Regards.

A.Banerjee ■

Ther are four types that I know of that are or have been in use:

1. Belt manufacturer's embedded antenna sensors with many variations such as Goodyear Sensor Guard.

2. Wire or bar shaped to impact idler trough strung between rollers and connected to a micro-switch either side of the loading station -- annuciates when tramp metal penetrates belt far enough to force cross-bar to trip micro-switch.

3. Collection tray with orifice and weigh bridge that annunciates with excessive flow that is placed under impact idler station

4. Ultrasonic sensor that has emmiter and receiver such that when belt is slit the signal is interrupted. There are variations of this that can be defeated by trnsmission through a wet product. ■

Note: in my above response, the cut has to penetrate the belt for all but the manufacturer's top cover embedded antennas. ■

Hi Larry

Of those that U mentioned, which is the best in yr opinion

I thought that (2) - was actived by a "finger" of belt hanging down from the cut belt and not the actual tramp steel. For this reason, they are (on our plant), installed after the feed skirt section. This is assuming that there is a finger of belt hanging down to trip the wire (which does seem to be case for us).

Cheers

James ■

Dear RJ,

No. 2 is activated by tramp material which punctures the belt. The penetrant is caught by the pinching action of the belt and moved forward till it hits a reaction point - the string or bar. The cross member is place just before each of the impact idler rolls. The string or bar then activate the micro-switch. There are many configurations of this theme.

In my opinion the best protection of belt puntures, on a 10 point scale, is as follows:

1. Curved hood and spoon of proper design .................. 10 pts.

2. Impact station cross member ..................................... 7 pts.

3. Embedded sensor/emitter/receiver ............................ 7 pts.

4. Collection tray ............................................................. 4 pts.

5. Ultrasonic sensor ....................................................... 2 pts.

Each of these has particular merits that exceed the features of the others. They can be additive as well as I note below. I see benefit to applying 1-4. I could elaborate on the reasoning, but, this thread would get too wordy.

The curved spoon can reduce the objects penetrating force below the necessary cutting force of rubber. Pieces can be too large to contain all possible damage. At Los Pelambres, a heavy piece of crusher liner (500 kg?) passed onto the belt without damaging it, but meters down the chute a cross-beam was layed (a shear bar of another designers whim) that caught the liner and slit the belt. About 2 km ( 5.5 minutes) of belt was slit before it was observed. Note: this ripping member was restrained after the impact station. If the belt antenna (or derivatives) was used it would have caught the damage.

Pieces can get caught under the skirt assembly as described by the thread starter. Its is most likely this type of damage would first scar the belt as we often see. More aggressive action will eventually cut through the top cover and beyond. This type of damage is somewhat protected by the embedded belt sensor. ■

Rakesh,

Goodyear Sensor Guard cannot sense foreign metal on the belt. It can only annuciate a tear of sufficient magnitude that breaks the embedded antenna loop.

A tramp metal (ferrous and non-ferrous) detector is required to annunciate tramp metal such as made by Outokumpa Oy of Finland or Tectron (USA).

Lawrence Nordell

www.conveyor-dynamics.com ■

Thanks Larry

On some of our steel cord belts - 24 yo...I was wondering how they were supposed to work - does not seem like U describe in 2.

We have one at the end of the feed skirts and also one on the return belt below the feed skirts...these are cross wires...with pull micro switch. I am guessing that the return belt one is a belt condition detector (ie loose fingers of belt projecting up) more than a rip detector....otherwise it will be a long rip!!!

I have seen at the Gladstone Port Authority the same - just after the feed skirts.

As liner plates (badly designed or using high tensile bolts/studs that we welded) tend to jam inside the chute and stay there (ripping the belt as it passes by), the system as mentioned by U ie in front of each impact idler makes more sense.

Cheers

James ■

James,

Thanks for the concept of splice failure detection at the tail (low tension). I had not thought of it. Although it only detects gross failure in steel cord movement it does offer a level of protection over operator detection. I believe it can detect bulges as well. Here, a rigid bar would be better than a flexible wire having the ability to flag earlier failures.

A single wire is no where as effective as multiple idler rolls. Often the penetrant pierces the belt and gets hung on one impact roll.

HNY,

Larry ■

Dear Mr. Rekhawar,

What I gather from GOOD YEAR catalouge is given below;

Sensor are embeded to belt at a distance based on their experience. Below the belt , detectors are located.As the conveyor moves, these sensors pass over the detectors which generate out-put pulses.If the belt begins to rip/cut, a sensor loop is also cut. As this cut loop passes over a detector, no pulse is generated. The lack of pulse is recognized by the control unit & the belt automatically shuts down to minimize further damage.

I also understand that you have to purchase belt from them only based on your specification .

I think I am able to delever some thing to you.

Regards.

A.Banerjee ■