Please help - Surface area calculation

I hope someone can help with this very simple problem that I can’t seem to solve by myself.

Our company receives tablets from a client and we package them in a pouching machine. The problem is this. Since the quantity (mass) of the tablets is large, and the surface area of the solitary piece of equipment is small, I get very large residual limits.

Should we be contacting the client and adding their equipment surface area (for the full train) to ours (for the single euipment) to determine the total surface area or is there some other calculation I’ve missed?

Please, any input is appreciated. I need to implement the CV plan soon and this is the only thing holding me up.


Dear Mr. Orbusmike,

In my opinion your approach (i.e. asking tablet manufacturer to provide you with the full equipment train surface area) is the most appropriate one.

If you have enough time and resources available, you may try to look into setting limits based on visual acceptance criterion (check with the tablet manufacturer if they have developed any visible residue limits, in most cases you may get lower limits using visual criterion than the conventional approaches of setting limits).



Dear Mr. Orbusmike,

How Do you perform pouch filling? whether it is weighing basis? if it is done by weighing basis (where only weighing balance is used-product contact will not be there to the balance Platform) you can go ahed with VRL method.


Thanks for the replies.

Pouching is done essentially the same as a tablet counter whereby tablets are loaded into a hopper, they fall into a bowl, the bowl vibrates them into place, and they travel past and electronic eye which counts the tablets. There is quite a bit of contact area but it still isn’t much compared to the large batch size.

I’ve included a visual LOD as part of the master plan so we will use visual detection but it was just going to be used as a determination of whether the equipment was clean enough to swab. I am pretty confident the high limits I’ve determined would be very noticeable visually.

I think I will try to get the surface area from the client and go forward with it. It seems a little disjointed but I think it will give me results that won’t be as shocking to an auditor and at least I can justify them.