Jump to content

  • Quick Navigation
Photo
- - - - -

Scales and Tolerances for Internal Daily Calibration

Scales Calibration Tollerances Weights

  • You cannot start a new topic
  • Please log in to reply
8 replies to this topic

#1 DavidAR

DavidAR

    Grade - MIFSQN

  • IFSQN Member
  • 116 posts
  • 13 thanks
2
Neutral

  • United Kingdom
    United Kingdom

Posted 30 May 2014 - 10:56 AM

Good day to all,

 

I am in my 3rd monthg of a new role as a supervisor and i have noted that the internal facility checks specifically SCALES are checked using a couple of old weights (to which i have not found a certificate for) and with those checks there isnt specified a tolelrance for each balance used.

 

By this i mean:

Scale A) UWE ADM 6000 Max 600g min 40g:

so what weights should be used to test this is working and what tollerance? 2 KG weight tollerance or +-2g? or should certain weights be used with a tollerance of a specific +- t odetermine if its out of spec? and not fit for use?

---Scale used for weighing product to 450g only---

 

T-scale T-130 Max 600KG x 0.1g Floor scales at moment are not being checked daily (used for weighing waste only) and i think a a matter of GMP we should be and if i use say a 10kg weight would this be ok? what would the tolerance be for out of spec? +- 2kg? i dont know...

 

uwe am-15k min 100g max 15kg  This scale is used for weighing finished boxed product 7kg 8kg and 9kg only. Curently using 2kg weight with a 5 kg weight and again there is no tollerance on thew sheet to define if its in spec or not so what would this scale be? +-2g? again im not sure.

 

finnaly STW-150ke max 150kg x10g this scale does not weigh end product but is used for weighing trays of product at a particular process step which is not a CCP i might add but again we use a 2 kg and 5 kg weight but no tollerance to define what is out of spec.

 

 

I have worked through 2 yrs back log of old calibration records with no out of spec recorded and although the scales since i have worked here have always read the same as the weights declared im not happy that i do not have a tolelrance to work by like we do with temperature probes.

 

I guess the 1st step is to send my weights off to get calibrated. but how do i go about the tollerances for the daily calibration checks?

I mean im not even certain the weights we are using are the right ones for the types of scale we are using.

 

The scale Guiy is coming out in june to do his annual checks and i have a million questions for him but it just seems that with BRC also due in june im concnerned this might be flagged as an issue..

 

 

any help advice welcome and appreciarted.

 

Regards

DaveAR

 

 


  • 0

#2 ncwingnut

ncwingnut

    Grade - MIFSQN

  • IFSQN Member
  • 75 posts
  • 14 thanks
3
Neutral

  • United States
    United States
  • Gender:Female
  • Location:North Carolina
  • Interests:Horses, Boxer dogs, cross stitch, MMORPGs, regulatory affairs stuff...and on and on....

Posted 30 May 2014 - 12:10 PM

We do checks at the beginning of each shift.  We also have our 3rd party come in every quarter to calibrate the scales, and if we have a scale out or not working, they are here within 2 hours.

 

Our tolerance is tighter than the 3rd party.  We check our scales with a 10lb weight and it's +/- .05.  so our range is 9.95 to 10.05.  I have our weights calibrated annually and I am also required to have the calibrations for the weights the 3rd party uses on file.  Everything also has to be done to an NIST or similar tracable standard.


  • 0

#3 DavidAR

DavidAR

    Grade - MIFSQN

  • IFSQN Member
  • 116 posts
  • 13 thanks
2
Neutral

  • United Kingdom
    United Kingdom

Posted 30 May 2014 - 02:52 PM

Yeh thats exactly how i expected to find our system based in uk i have seen this sort of standard used in many buisness but this one doesnt have anything just an uncalibrated weight set which they place on and enter the value displayed...

 

How do you come up with the tollerance for a given scale weight set? ie Floor scales tollerance would be in KG's and smaller scales id assume would use +-2g's ish?

 

I would ideally like to figure out the tolelrance for my scales so as to create a new document that is more clear whats accedptable and not for those checking them.

 

Obviously i need to then figure out if the weights i have are the most suitable for the types of scales i have and get them calibrated!

 

Any ideas on how to work out the tollerances or weights required given a particular set of scales?


  • 0

#4 YongYM

YongYM

    Grade - MIFSQN

  • IFSQN Member
  • 230 posts
  • 52 thanks
6
Neutral

  • Malaysia
    Malaysia
  • Gender:Male
  • Location:Malaysia
  • Interests:Reading, Watching TV, Singing Karaoke & Sight-seeing

Posted 31 May 2014 - 02:44 AM

To DavidAR:

 

First, you need to verify the weight according to your working range e.g. if you normally weigh from 100 - 450g using that particular weighing scale, please make sure you verify the accuracy of the weight covering the working range (<100g and >450g).

 

In terms of tolerance, you may check your weighing scale or consult your supplier what is the 'graduation' e.g. when you measure a particular item for example 200g sample, do you realize that the reading goes from (a) 198g, 199g, 200g, 201g then 200g and stabilized OR (b) 196g, 198g, 200g, 202g then 200g  again and stabilized. For (a), you can set your tolerance as ±1g while for (b) you can set as ±2g. However, it also depends on how critical the reading to you. You may also set as ±2g, ±3g.... for (a) and ±4g, ±6g or ... for (b).  


  • 2

Thanked by 1 Member:

#5 Slab

Slab

    Grade - SIFSQN

  • IFSQN Senior
  • 284 posts
  • 123 thanks
47
Excellent

  • United States
    United States
  • Gender:Male
  • Location:The Heel of the Boot
  • Interests:Reading (history, science fiction), Photography, drawing,food safety, metrology, TQM, hoplology, etc.

Posted 31 May 2014 - 08:59 PM

You may find this helpful;

 

Attached File  NIST Handbook 44.pdf   4.11MB   171 downloads

 

I agree with, YongYM.  Consult with your scale manufacturer for tolerances, as this will change with type and range of function. Our scales have conveniently come with spec placards on the back (Doran 8000 series).  Scales will drift based upon numerous environmental conditions and even location as Earth's Gravity can vary 0.5%.

 

 


  • 1

Food Safety News  Marine Stewardship Council  Blue Ocean Institute  

 

"Some people freak out when they see small vertebra in their pasta" ~ Chef John


#6 jel

jel

    Grade - MIFSQN

  • IFSQN Member
  • 113 posts
  • 32 thanks
13
Good

  • Mexico
    Mexico
  • Gender:Male

Posted 01 June 2014 - 02:11 PM

Good day to all,

 

I am in my 3rd monthg of a new role as a supervisor and i have noted that the internal facility checks specifically SCALES are checked using a couple of old weights (to which i have not found a certificate for) and with those checks there isnt specified a tolelrance for each balance used.

 

By this i mean:

Scale A) UWE ADM 6000 Max 600g min 40g:

so what weights should be used to test this is working and what tollerance? 2 KG weight tollerance or +-2g? or should certain weights be used with a tollerance of a specific +- t odetermine if its out of spec? and not fit for use?

---Scale used for weighing product to 450g only---

 

T-scale T-130 Max 600KG x 0.1g Floor scales at moment are not being checked daily (used for weighing waste only) and i think a a matter of GMP we should be and if i use say a 10kg weight would this be ok? what would the tolerance be for out of spec? +- 2kg? i dont know...

 

uwe am-15k min 100g max 15kg  This scale is used for weighing finished boxed product 7kg 8kg and 9kg only. Curently using 2kg weight with a 5 kg weight and again there is no tollerance on thew sheet to define if its in spec or not so what would this scale be? +-2g? again im not sure.

 

finnaly STW-150ke max 150kg x10g this scale does not weigh end product but is used for weighing trays of product at a particular process step which is not a CCP i might add but again we use a 2 kg and 5 kg weight but no tollerance to define what is out of spec.

 

 

I have worked through 2 yrs back log of old calibration records with no out of spec recorded and although the scales since i have worked here have always read the same as the weights declared im not happy that i do not have a tolelrance to work by like we do with temperature probes.

 

I guess the 1st step is to send my weights off to get calibrated. but how do i go about the tollerances for the daily calibration checks?

I mean im not even certain the weights we are using are the right ones for the types of scale we are using.

 

The scale Guiy is coming out in june to do his annual checks and i have a million questions for him but it just seems that with BRC also due in june im concnerned this might be flagged as an issue..

 

 

any help advice welcome and appreciarted.

 

Regards

DaveAR

In principle, all measurements should be traceable to the International System of Units, otherwise the measurement is invalid. The ISO 17025:2005 Standard provides requirements to ensure that the measurements are reliable. 
 
Furthermore, the resolution of your instrument should be one that allows you to meet the regulatory standards of tolerance towards the consumer, and not according to your measuring instrument

  • 0

#7 DavidAR

DavidAR

    Grade - MIFSQN

  • IFSQN Member
  • 116 posts
  • 13 thanks
2
Neutral

  • United Kingdom
    United Kingdom

Posted 01 June 2014 - 07:17 PM

Thank you for all replies im still a little stuck on how to proceed further, al lthe scales in this small ltd company are a little old and some are worn beyond the point of being used anymore. the scale company that comes out this month I will have to raise these issues with them to see if they can sort it out I have approached management with regards to these scales and the issues im trying to address but it falls on deaf ears.

 

I will continue to try and sort this issue out amongst a host of others... Thanks


  • 0

#8 Slab

Slab

    Grade - SIFSQN

  • IFSQN Senior
  • 284 posts
  • 123 thanks
47
Excellent

  • United States
    United States
  • Gender:Male
  • Location:The Heel of the Boot
  • Interests:Reading (history, science fiction), Photography, drawing,food safety, metrology, TQM, hoplology, etc.

Posted 02 June 2014 - 02:42 AM

Thank you for all replies im still a little stuck on how to proceed further, al lthe scales in this small ltd company are a little old and some are worn beyond the point of being used anymore. the scale company that comes out this month I will have to raise these issues with them to see if they can sort it out I have approached management with regards to these scales and the issues im trying to address but it falls on deaf ears.

 

I will continue to try and sort this issue out amongst a host of others... Thanks

 

If a scale cannot calibrate then it must be removed from productive use.  The floor scale used for waste does not need a calibration record as long as a) the waste is not billed for reclamation, and b) it is clearly marked "for waste only" in languages suitable for the staff.

There is a huge difference between a calibration check and actual calibration.  Very few facilities are staffed for calibration, and rely more on checks for serviceability.  Where actual calibration procedures are performed then a traceable standard is required (and it's proof on file).  A daily (or perhaps even a greater frequency because of use) calibration check is more or less just an analog.  You could use traceable standards, but these are extremely expensive and prohibitive to many companies on a tight budget.

Now whether deaf ears prevail or not, you might want to put a little scare on some ass with terms such as "facilitation of Fraud" if you have measuring devices unsuitable for the intent. :shades:   

 

Here is the SQF code;
 

11.2.10.1 The methods and responsibility for the calibration and re-calibration of measuring, test and

inspection equipment used for monitoring activities outlined in pre-requisite program, food safety plans and

food quality plans and other process controls, or to demonstrate compliance with customer specifications shall

be documented and implemented.

 

11.2.10.2 Procedures shall be documented and implemented to address the disposition of potentially affected

products should measuring, test and inspection equipment be found to be out of calibration state.

 

11.2.10.3 Calibrated measuring, test and inspected equipment shall be protected from damage and

unauthorized adjustment.

 

11.2.10.4 Equipment shall be calibrated against national or international reference standards and methods or to

accuracy appropriate to its use. In cases where standards are not available, the supplier shall provide evidence

to support the calibration reference method applied.

 

11.2.10.5 Calibration shall be performed according to regulatory requirements and/or to the equipment

manufacturers recommended schedule.

 

11.2.10.6 Calibration records shall be maintained.

 


  • 0

Food Safety News  Marine Stewardship Council  Blue Ocean Institute  

 

"Some people freak out when they see small vertebra in their pasta" ~ Chef John


#9 Charles.C

Charles.C

    Grade - FIFSQN

  • IFSQN Moderator
  • 12,454 posts
  • 3244 thanks
347
Excellent

  • Earth
    Earth
  • Gender:Male
  • Interests:SF
    TV
    Movies

Posted 02 June 2014 - 06:48 AM

Dear David,

 

No idea about UK but in many places, a commercially distributed balance is legally required to show the official, original authorized label which proves it was (at least) calibrated at that time. No label > unusable. Plus IMEX it is illegal to self-replace internal broken springs (for rather obvious reasons).

 

Regarding specific calibration earlier (Yong) post gives a lot of the desirable checking expectations. It's a 2-way thing, specification + usage, presumably whichever is the smaller.

I presume all yr balances are analog, ie spring. IMEX these are specified as typically around 5% max.error at full reading.

Lists of typical tolerances when evaluated with checkweights do exist.

Some manufacturers, eg digital balances, specify an acceptable tolerance as per their own issued calibration procedure.

 

Rgds / Charles.C


  • 0

Kind Regards,

 

Charles.C






Also tagged with one or more of these keywords: Scales, Calibration, Tollerances, Weights

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users