11 replies to this topic

[Rachu19]

hello there, 

 

We have a pipeline Metal detector to check our products(Sauces). we carried out a challenge testing using a metal clip which we use to seal our bags. the metal detector alarms, but the piece does not get rejected into the reject bin. we had to dismantle the depositor and the pipes and found the pieces inside the depositor. we thought this could be due to reject delay timing set on the MD, but even after increasing the timings it did not help. For me this is a complete failure of our CCP.

 

We called the external engineers who calibrate our machines to be told we might have to change our metal detector.

 

can anyone help on how we can get around this issue, is there an industry guideline for pipeline MD?

 

thanks 

Rachu

[QAGB]

hello there, 

 

We have a pipeline Metal detector to check our products(Sauces). we carried out a challenge testing using a metal clip which we use to seal our bags. the metal detector alarms, but the piece does not get rejected into the reject bin. we had to dismantle the depositor and the pipes and found the pieces inside the depositor. we thought this could be due to reject delay timing set on the MD, but even after increasing the timings it did not help. For me this is a complete failure of our CCP.

 

We called the external engineers who calibrate our machines to be told we might have to change our metal detector.

 

can anyone help on how we can get around this issue, is there an industry guideline for pipeline MD?

 

thanks 

Rachu

 

 

I'm surprised your metal detection company can't offer to fix your depositor. Can you actually set the length of time the product is ejected from the metal detector? You're going to lose product, but you'll not have metal just sitting inside your equipment. If the length of rejection time doesn't fix it, then there's either a flaw with the depositor or the flow of your product is not forceful enough to remove the metal. I think you should look at that first to find out why the metal isn't being rejected.

 

An alternative (not really the best alternative since it doesn't fix your rejection issue) would be to put a filter/sieve (and possibly magnet as well) before your metal detector. That way you can capture the larger foreign material, and most metals. It will help reduce some of your issues...but I would suggest you dig deeper into your metal detector's rejection situation first. There's no good enough reason why you should have the metal clip stuck inside the equipment.

[Eric G]

1) Are you testing inline with other types of contaminants? If so are they being correctly rejected? 

2) You must also consider the flow rate, pipe diameter and response time of the reject valve and distance between the MD and valve.  It is completely possible that it just isn't going into reject fast enough.  If you can supply those numbers, i'll be happy to run them for you. 

 

Which brand of MD do you use? 

 

Eric

[SQFconsultant]

Have the company that installed the inline system check the flow speed (speed of product moving thru the pipe) and time the system that way - this happened to a client and what they decided on was to do a two stage detection due to speed of the line.

 

So there is technically a "redundant" detector after the first one - the first one is located about 50 feet before the blow out point, once detected a gate closes to any further product coming thru and the product speed is greatly reduced so that by the time it gets to the second stop it has slowed down very much and then an entire 50-75 feet of sauce is blown out. 

 

They are now trying to get it down to 10-20 feet.

[AJL]

Hi, I can see that this is an old post, but we are looking at installing a pipeline metal detector, do they work? What are the limitations?
How do you insert test Pieces when it is a closed pipe? So many questions

[Eric G]

Hi AJL, 

 

Pipeline metal detectors work well.  Usually they excel in performance compared to using a conveyor style system further downstream due to small aperture and constant flow where both sides of the metal detector coils see the same thing most of the time.  The result is very little product effect and very good performance. 

 

The challenge is in determining the correct non-metal inspection pipe that meets the specified temperature and pressure for your application and also confirming the rejection is possible when taking into account the flow rate and reject valve response time.  If the flow is too high, or reaction time too short more distance will be needed between the metal detector and reject valve. If the the flow can start and stop intermittently then this should also be considered to ensure the flow persists when a detection occurs at least until the contaminant can be rejected. 

 

Testing can be messy.  It is pretty common to see these tested between the pipe and aperture opening. However, inline testing is prudent to ensure detection and rejection.  Usually, inline testing is done using a test ball insertion port upstream of the system, and a small catch pipe downstream.  If the ball doesn't reject from the valve it will be caught in bars that are oriented across the flow. 

 

I think most users will run inline test initially to determine performance and timing initially then start doing the easier test for most verifications.   Reject confirmation should be used and tuned up during the inline test to ensure the valve reaction is always adequate and monitored for every detection event. 

 

I know that Fortress Technology offers a unique feature called Halo which can simulate detection in the center of the aperture and is calibrated to known spherical contaminants.  This would a better test then alongside the pipe, and much cleaner than inline.  

[AJL]

Thanks Eric!!! Very helpful.
I have been on you tube a lot and can see that a lot of people use strips, but I realised it's necessary to test how it would happen in 'real life to ensure the functionality of the reject.
I guess my mind was struggling with, where do you insert the ball in a practical sense, if it's closed? I just don't really understand where you would add the piece?
Maybe I am just a bit slow herr, but if my pipe is closed??
Any videos or photos you could share, to help with my slow brain connections here.
:)

[Eric G]

Fortress' Demo video link here; 

 

It show insertion at about 1:30.

 

Eric 

[AJL]

Eric!! Thank you!!! Fantastic video. Best one I had seen. Makes it very clear.
How often would you consider it necessary to use the balls?? Weekly? At start up?
Does it interfere with flow, doing the calibration?
Thag would really screw up our process.
The ice cream goes into cones, and the cones would not stop just because the ice cream did ....

[AJL]

Thank you!!! Thank you to all the incredibly people on the forum! Especially you Eric

[Eric G]

AJL, 

 

I can't really comment on the frequency of the test ball test versus along side.  In my opinion it would be at least weekly, if not daily.  

 

The catch pipe may very slightly affect the flow depending on the product inspected. If it is chunky and getting caught in the bars then there would be effect to be concerned with. If it is a homogenous product then probably by only a negligible amount.  It is a pretty common method where I am not aware of many such problems. 

 

Eric 

[Charles.C]

Also see -

 

https://www.ifsqn.co...rs/#entry183656