Seraphin E3, 5 gallon prover calibration needed

[WestCoastCal]

We are having a hard time finding a lab to cal this, our previous vendor is no longer able to cal this.
We need to get our graduated neck, stainless steel, 5 gallon prover calibrated using the volume transfer method. The calibration is to include 5 gallon accuracy and neck scale measurement accuracy.
The liquid temperature measurement standard and calibrated volumetric standards must be traceable to NIST (traceability to foreign labs is not acceptable).  If ambient conditions (temperature/humidity/barometric pressure) affect the calibration, the affecting ambient conditions must be monitored/reported with calibrated standards.
The neck scale correction value must be calculated and reported as part of the calibration certificate
All standards must have a valid calibration and have a recall/calibration due date.
Your facility must allow a survellience inspector to "watch" the calibration
We realize that it may not be possible to maintain a 4:1 test accuracy ratio, if this is the case, test ratios (preferably) or measurement uncertainties must be supplied.
Previously in the past, this prover was assigned a special calibration, "Use reported values and uncertainties"---This would be fine to continue on future calibrations.  If your lab can perform this calibration, please PM me or supply contact info on the forum.

[OlDave]

Give the Minnesota State Lab a call. It looks like that is on their NVLAP scope of accreditation.
They do an excellent job with mass for me.

Minnesota Department of Commerce
Weights and Measures Division
14305 Southcross Drive W.
Burnsville, MN 55306

Phone: 651-215-5821
FAX: 952-435-4040
TTY: 952-435-5045

http://mn.gov/commerce/weights-and-measures/topics/metrology/Metrology-Lab-Services.jsp

[Squidley]

Seraphin still makes these. don't they have a cal service?

[spanishfly25]

Do I am missing something here? they are very easy to calibrate I don't know why are you having problems finding a vendor, unless is something different from what I am thinking it is. We use a scale and DI water. clean the prover real good, weight it.(tare the scale with the empty prover) fill it with DI water to the 5 gallon mark and calculate the volume.  (scale reading X  water K factor) You need to know the temperature of the water so you can use the correct K factor. Water is an acceptable standard. The scale and temperature meter need to be NIST traceable, but almost every lab has those items

[OlDave]

Spanishfly,
WestCoastCal stated

We need to get our graduated neck, stainless steel, 5 gallon prover calibrated using the volume transfer method.

While the gravimetric method you describe is a valid method for calibration of a prover, that isn't what WCC was asking for.

[Phys_dim]

I am missing something, wouldn't it be better to have this calibration done using the gravimetric method? 

I am sure you guys will beat me up some  ... so I am going to reference NIST SP 250-72.

[Phys_dim]

also, WCC may not be able to go all the way to the Minnesota State Lab ... "Your facility must allow a survellience inspector to "watch" the calibration"

hmmm...what the customer wants, versus the cost.

[OlDave]

Actually I agree with you Phys_dim. If it was mine, I would prefer gravimetric testing. But that wasn't what the help request was for.

If they hurry they can get in and out of MN before the state freezes over for the winter.

[spanishfly25]

I work in pharmaucetical companies and once I had to have an inspector watch me do the calibration. the reason is that they wanted to do the calibration with the same fluids as the unit was use with. so we prepare the solution that included narcotics and that's why the inspector was present. then we had to find out the density of the solution, I wonder is the same case with WCC or something similar.

[jimmyc]

I work in pharmaucetical companies and once I had to have an inspector watch me do the calibration. the reason is that they wanted to do the calibration with the same fluids as the unit was use with.

i guess now i am missing something, how could you calibrate volume using an unknown density? isn't that the reason for distilled water? it seems like knowing the true volume and the weight of the unknown would give you the density?  The mass density or density of a material is its mass per unit volume.

[spanishfly25]

you determine the density of the fluid before performing the cal of the prover. in short we perform two calibations, first we calibrated the fluid and then the prover.

[WestCoastCal]

Thanks for all the great feedback, our customer will accept a gravimetric cal.  I didn't understand the methodologies--thanks Phys_dim for poinitng out SP250-72!  I'm not even going to waste my time trying to figure out why they wanted a volume transfer method cal or if someone just made an arbitrary decision.  Still have to try to find a vendor, hopefully the local vendor that could not meet the programmatic requirements for the VTM cal can meet the programmatic requirements of a gravimetric cal.