Frequency of Scale Calibrations

HI everyone, 

i'm looking for some insight as to the frequency of our scale calibrations.

we are a distribution center and use the scales everyday. 

We do in house scale verification on a daily basis with Certified ansi weights which are sent out for annual calibration. 

the company currently has a 3rd party scale company come in on a quarterly basis and calibrate the scales. 

To me this is over kill with us doing daily verification using certified weights on top of them coming in quarterly.

Our customer requires us to do the daily checks on all scales, but there is nothing about the frequency of having the scales calibrated.

I have always worked in USDA facilities and we had to have the scales calibrated by the state/ city on an annual basis. 

Can anyone help me find the regulations or guidance on this?

Thanks

Weebus

I ran a level 3 SQF facility and it was done annually or if the scale was below/above tolerance. We packaged cheese and used retail scales, box scales and pallet scales. Never was questioned on it. Much like you, we did daily verifications in house.

Hi Weebus,

As per the second post, the relevant question may be as to whether yr procedure / tolerances are "satisfactory" to sqf.

I experienced a similar (non-sqf) situation with a 15kg digital lab balance. The guy who came to calibrate used an identical procedure to myself except that his certified weights were stainless steel and not bronze. He also had specific tolerance data as supplied by the manufacturer which I copied.

I subsequently bought some SS certified weights and continued on my own. No problems.

This assumes that there is no specific stipulation to use an external body of course.

addendum

On re-reading I realized yr original query - frequency of calibration - got side-tracked. My apologies.

There may be a terminological issue here. Such has occurred previously.

The activity you refer to as "verification" I call "calibration" as far as the balance is concerned. It's true that my activity is carried out using "sub-master" weights which are derived from the certified masters but this is a perfectly acceptable procedure.

I describe the daily checking activity as "daily calibration" and no auditor has ever challenged this.

The master weights (primary standards) used to internally generate the sub-masters are sent out for annual certification by an official certification  lab. using traceable standards. This method  has aways been auditorially acceptable.

Can anyone help me find the regulations or guidance on this?

 As per above, it maybe needs to be determined what the "this" actually is.

IMEX there are 2 requirements from a procedural POV - 

(a) A procedure to defne the frequency of (my) calibration

(b) A procedure to operate/maintain the balances in routine use

For (a) -

Generic  procedures exist whereby a "high" frequency of calibration (my terminology) is initially used. Standard methods/rules have been published (attached on this forum)  which read something like - If no failure of specified tolerances in a X month period (eg 6-months) occurs, can reduce the frequency by Y% (typically 10-20% from memory). And so on. This method is called the "ladder" procedure. in yr case, the initial frequency might have been twice daily such that if no failures the frequency could be reduced progressively to daily. i imagine you are happy with a daily check so no reason to investigate further.

(b)

Examples of this have been attached on the forum, they are all pretty similar. The procedures usually  include a proviso for action where failure of a balance to maintain (my) calibration occurs. 

Hope the above makes sense. :smile:

Thank you everyone!

it's all very helpful!