Nist Traceable Calibration Weights
Precision Weighing Balances
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certified weights

(7-10 days lead time for all calibration weights and mass sets)
Metric Weight Tolerances - all tolerances stated in milligram (mg)
Calibration Weights Includes Certificate of Calibration
Nominal
Value
Class Part Number Report of
Traceability
NVLAP
Certification
Tolerance Price
Cylindrical Shape        
30 kg Class 1 PWB8100W NO YES ± 75 mg
$2025.00
25 kg Class 1 PWB8102W NO YES ± 62 mg
$1600.00
20 kg Class 1 PWB8106W NO YES ± 50 mg
$1360.00
10 kg Class 1 PWB8110W NO YES ± 25 mg
$959.00
5 kg Class 1 PWB8114W NO YES ± 12 mg
$742.00
5 kg Class 1 PWB8116W NO YES ± 12 mg
$500.00
4 kg Class 1 PWB8120W NO YES ± 12 mg
$462.00
3 kg Class 1 PWB8122W NO YES ± 7.5 mg
$389.00
2 kg Class 1 PWB8124W NO YES ±5.0 mg
$281.00
1000 g Class 1 PWB8128W NO YES ±2.5 mg
$227.00
500 g Class 1 PWB8132W NO YES ±1.2 mg
$217.00
300 g Class 1 PWB8136W NO YES ±.75 mg
$194.00
200 g Class 1 PWB8138W NO YES ±0.50 mg
$181.00
laboratory weights

(7-10 days lead time for all calibration weights and mass sets)
Nominal
Value
Class Part Number Report of
Traceability
NVLAP
Certification
Tolerance Price
Small Knob Style, ASTM Shape        
500 g Class 1 PWB7014-1W NO YES ±1.2 mg
$287.00
300 g Class 1 PWB7015-1W NO YES ±0.75 mg
$237.00
200 g Class 1 PWB7016-1W NO YES ±0.50 mg
$230.00
100 g Class 1 PWB7017-1W NO YES ±0.250 mg
$128.00
50 g Class 1 PWB7018-1W NO YES ±0.120 mg
$115.00
30 g Class 1 PWB7019-1W NO YES ±0.074 mg
$113.00
20 g Class 1 PWB7020-1W NO YES ±0.074 mg
$113.00
10 g Class 1 PWB7021-1W NO YES ±0.050 mg
$112.00
5 g Class 1 PWB7022-1W NO YES ±0.034 mg
$103.00
2 g Class 1 PWB7024-1W NO YES ±0.034 mg
$102.00
1 g Class 1 PWB7025-1W NO YES ±0.034 mg
$102.00
milligram weights, mass set
calibration leaf weights

(7-10 days lead time for all calibration weights and mass sets)
Photo shown above for the flat weights are of OIML specification weights.
The ASTM weights are actually square in their shape.
 
Nominal
Value
Class Part Number Report of
Traceability
NVLAP
Certification
Tolerance Price
Flat Weights, ASTM Shape        
500 mg Class 1 PWB7026-1W NO YES ±0.010 mg
$ 103.00
200 mg Class 1 PWB7028-1W NO YES ±0.010 mg
  $ 103.00
100 mg Class 1 PWB7029-1W NO YES ±0.010 mg
  $ 103.00
50 mg Class 1 PWB7030-1W NO YES ±0.010 mg
  $ 103.00
20 mg Class 1 PWB7032-1W NO YES ±0.010 mg
  $ 103.00
10 mg Class 1 PWB7033-1W NO YES ±0.010 mg
  $ 103.00
5 mg Class 1 PWB7034-1W NO YES ±0.010 mg
  $ 103.00
3 mg Class 1 PWB7035-1W NO YES ±0.010 mg
  $ 103.00
2 mg Class 1 PWB7036-1W NO YES ±0.010 mg
  $ 103.00
1 mg Class 1 PWB7037-1W NO YES ±0.010 mg
  $ 103.00
The weight value can deviate above or below the nominal value by the tolerance defined.  To determine the tolerance of a mass, look at the denomination or nominal value of the weight and the appropriate class you need.
Custom weight sets are available upon request by calling
Precision Weighing Balances at 978-521-7095
All calibration weights are not returnable.  Once your order has been placed it CAN NOT be cancelled.  Please carefully consider this prior to placing your order.  The reason for this is these weights are custom manufactured and are certified on the date they were made.  In addition, if you touch the calibration weight with your fingers the oil in your skin would change the tolerance and we can not take this chance if the weight was returned.
laboratory weights

(7-10 days lead time for all calibration weights and mass sets)
Metric Weight Tolerances - all tolerances stated in milligram (mg)
Calibration Weights Includes Report of Traceability
Nominal
Value
Class Part Number Report of
Traceability
NVLAP
Certification
Tolerance Price
Cylindrical Shape        
30 kg Class 1 PWB8100T YES NO ± 75.00 mg
$1905.00
25 kg Class 1 PWB8102T YES NO ± 62.00 mg
$1555.00
20 kg Class 1 PWB8106T YES NO ± 50.00 mg
$1320.00
10 kg Class 1 PWB8110T YES NO ± 25.00 mg
$909.00
5 kg Class 1 PWB8114T YES NO ± 12 mg
$645.00
5 kg Class 1 PWB8116T YES NO ± 12 mg
$428.00
4 kg Class 1 PWB8120T YES NO ± 12 mg
$399.00
3 kg Class 1 PWB8122T YES NO ± 7.5 mg
$316.00
2 kg Class 1 PWB8124T YES NO ±5.0 mg
$228.00
1000 g Class 1 PWB8128T YES NO ±1.2 mg
$179.00
500 g Class 1 PWB8132T YES NO ±1.2 mg
$156.00
300 g Class 1 PWB8136T YES NO ±.75 mg
$137.00
200 g Class 1 PWB8138T YES NO ±0.50 mg
$136.00
precision calibration weights
(7-10 days lead time for all calibration weights and mass sets)
Nominal
Value
Class Part Number Report of
Traceability
NVLAP
Certification
Tolerance Price
Small Knob Style, ASTM Shape        
100 g Class 1 PWB7017-1T YES NO ±0.250 mg
$110.00
50 g Class 1 PWB7018-1T YES NO ±0.120 mg
$100.00
30 g Class 1 PWB7019-1T YES NO ±0.074 mg
$100.00
20 g Class 1 PWB7020-1T YES NO ±0.074 mg
$80.00
10 g Class 1 PWB7021-1T YES NO ±0.050 mg
$80.00
5 g Class 1 PWB7022-1T YES NO ±0.034 mg
$79.00
2 g Class 1 PWB7024-1T YES NO ±0.034 mg
$79.00
1 g Class 1 PWB7025-1T YES NO ±0.034 mg
$79.00
balance caliration service
milligram leaf weight
(7-10 days lead time for all calibration weights and mass sets)
Photo shown above for the flat weights are of OIML specification weights.
The ASTM weights are actually square in their shape.
 
Nominal
Value
Class Part Number Report of
Traceability
NVLAP
Certification
Tolerance Price
Flat Weights, ASTM Shape        
500 mg Class 1 PWB7026-1T YES NO ±0.010 mg
$76.00
200 mg Class 1 PWB7028-1T YES NO ±0.010 mg
  $76.00
100 mg Class 1 PWB7029-1T YES NO ±0.010 mg
  $76.00
50 mg Class 1 PWB7030-1T YES NO ±0.010 mg
  $76.00
20 mg Class 1 PWB7032-1T YES NO ±0.010 mg
  $76.00
10 mg Class 1 PWB7033-1T YES NO ±0.010 mg
  $76.00
5 mg Class 1 PWB7034-1T YES NO ±0.010 mg
  $76.00
2 mg Class 1 PWB7036-1T YES NO ±0.010 mg
  $76.00
1 mg Class 1 PWB7037-1T YES NO ±0.010 mg
  $76.00
The weight value can deviate above or below the nominal value by the tolerance defined.  To determine the tolerance of a mass, look at the denomination or nominal value of the weight and the appropriate class you need.
Custom weight sets are available upon request by calling
Precision Weighing Balances at 978-521-7095
All calibration weights are not returnable.  Once your order has been placed it CAN NOT be cancelled.  Please carefully consider this prior to placing your order.  The reason for this is these weights are custom manufactured and are certified on the date they were made.  In addition, if you touch the calibration weight with your fingers the oil in your skin would change the tolerance and we can not take this chance if the weight was returned.
 
avoirdupois weights
Metric Weight Tolerances - all tolerances stated in milligram (mg) Statement Of Accuracy included
Note Traceable or NVLAP calibration certificate available AT ADDITIONAL COST
Nominal
Value
Class Part Number Certification Tolerance Price
30 kg Class 2 TR8200 Optional - click here ± 150 mg
$1485.00
25 kg Class 2 TR8202 Optional - click here ± 125 mg
$1238.00
20 kg Class 2 TR8206 Optional - click here ± 100 mg
$1074.00
10 kg Class 2 TR8210 Optional - click here ± 50 mg
$705.00
8 kg Class 2 TR8212 Optional - click here ± 50 mg
$705.00
5 kg Class 2 TR8214 Optional - click here ± 25 mg
$465.00
5 kg Class 2 TR8216 Optional - click here ± 25 mg
$304.00
4 kg Class 2 TR8220 Optional - click here ± 25 mg
$299.00
3 kg Class 2 TR8222 Optional - click here ± 15 mg
$239.00
2 kg Class 2 TR8224 Optional - click here ± 10 mg
$149.00
1000 g Class 2 TR8228 Optional - click here ± 5 mg
$119.00
500 g Class 2 TR8232 Optional - click here ±2.5 mg
$98.00
400 g Class 2 TR8234 Optional - click here ±2.5 mg
$106.00
300 g Class 2 TR8236 Optional - click here ±1.5 mg
$82.00
200 g Class 2 TR8238 Optional - click here ±1.0 mg
$76.00
100 g Class 2 TR8244 Optional - click here ±0.5 mg
$63.00
50 g Class 2 TR8252 Optional - click here ±0.25 mg
$59.00
20 g Class 2 TR8256 Optional - click here ±0.1 mg
$59.00
10 g Class 2 TR8258 Optional - click here ±0.074 mg
$59.00

(7-10 days lead time for all calibration weights and mass sets)

50 LB Cast Iron Test Weight

Quality Guaranteed by the Toughest Standards of All… Our Own.

Designed for scale calibration, our solid cast iron test weights are sealed to ASTM classes 6 and 7 specifications; Class F tolerances are listed in the National Institute of Standards and Technology Handbook 105-1.  All weights are traceable to NIST.  To verify adherence to class F tolerances, OPTIONAL traceable certificates are available for an additonal $75.00. 

Our cast iron weights undergo a special phosphatizing process in which the metal is thoroughly cleaned and mildly etched to allow exceptional finish adhesion.  The weights are then coated with a layer of chip-resistant paint which conforms to NIST Handbook 105-1 standards.  This two-step process ensures a long-lasting finish that greatly reduces the possibility of corrosion.
Complete Listing of all Available Cast Iron Grip Handle Weights
WITHOUT traceability certificate
Nominal
Value
Class Tolerance Part Number Weight Dimensions Price
1lb Class 7 ± 210 mg 12876 1.63" x 2.63" x 1.25"
$50.00
2 lb Class 7 ± 300 mg 12874 2.06" x 3.13" x 1.63
$60.00
5 lb Class 7 ± 750 mg 12823 2.63" x 4" x 3"
$65.00
10 lb Class 7 ± 1 g 12828 3.25" x 5" x 3.88"
$84.50
20 lb Class F ± 1 g 12870 5.87" x 4.5" x 5"
$109.90
25 lb Class F ± 1.1 g 12833 4.38" x 6.63" x 4.93"
$133.90
50 lb Class F ± 2.3 g 12839 5.63" x 7.88" x 6.38"
$146.90
5 kg Class 7 ± 1.4 g 12786 3.25" x 5.38" x 4"
$80.00
10 kg Class F ± 2.2 g 12767 4.5" x 6" x 4.94"
$100.00
20 kg Class F ± 2.0 g 12771 7.75" x 5.63" x 5.88"
$128.70
25 kg Class F ± 2.5 g 12775 5.38" x 8" x 7"
$170.00
All calibration weights are not returnable.  Once your order has been placed it CAN NOT be cancelled.  Please carefully consider this prior to placing your order.  The reason for this is these weights are custom manufactured and are certified on the date they were made.  In addition, if you touch the calibration weight with your fingers the oil in your skin would change the tolerance and we can not take this chance if the weight was returned.

avoirdupois weights
Calibration weights - all tolerances stated in milligram (mg) Statement Of Accuracy included
Note Traceable or NVLAP calibration certificate available AT ADDITIONAL COST
Nominal
Value
Class Part Number Certification Tolerance Price
50 lb grip Class F TR1276 Optional - click here ± 2.3 g
$796.00
30 lb grip Class F TR1275 Optional - click here ± 1.4 g
$623.00
25 lb grip Class F TR1274 Optional - click here ± 1.1 g
$525.00
20 lb grip Class F TR1272 Optional - click here ± 910 mg
$475.00
10 lb grip Class F TR1270 Optional - click here ± 450 mg
$292.00
10 lb Class F TR1201 Optional - click here ± 450 mg
$189.00
5 lb Class F TR1203 Optional - click here ± 230 mg
$122.00
2 lb Class F TR1209 Optional - click here ± 91.0 mg
$77.00
1 lb Class F TR1211 Optional - click here ± 70.0 mg
$56.00
12 oz Class F TR1212 Optional - click here ±70.0 mg
$47.00
8 oz Class F TR1213 Optional - click here ±45.0 mg
$46.00
4 oz Class F TR1215 Optional - click here ±23.0 mg
$41.00
2 oz Class F TR1217 Optional - click here ±11.0 mg
$36.00
1 oz Class F TR1220 Optional - click here ±5.4 mg
$33.00
1/2 oz Class F TR1222 Optional - click here ±2.8 mg
$33.00
1/4 oz Class F TR1224 Optional - click here ±1.7 mg
$25.00
1/8 oz Class F TR1226 Optional - click here ±1.3 mg
$25.00
1/16 oz Class F TR1228 Optional - click here ±1.1 mg
$25.00

(7-10 days lead time for all calibration weights and mass sets)
 
avoirdupois weights
Metric Weight Tolerances - all tolerances stated in milligram (mg) Statement Of Accuracy included
Note Traceable or NVLAP calibration certificate available AT ADDITIONAL COST
Nominal
Value
Class Part Number Certification Tolerance Price
30 kg Class 2 TR8200 Optional - click here ± 150.00 mg
$1,400.00
25 kg Class 2 TR8202 Optional - click here ± 125.00 mg
$1,168.00
20 kg Class 2 TR8206 Optional - click here ± 100.00 mg
$1,014.00
10 kg Class 2 TR8210 Optional - click here ± 50.00 mg
$665.00
5 kg Class 2 TR8216 Optional - click here ± 25 mg
$286.00
4 kg Class 2 TR8220 Optional - click here ± 25 mg
$293.00
3 kg Class 2 TR8222 Optional - click here ± 15 mg
$226.00
2 kg Class 2 TR8224 Optional - click here ± 10.0 mg
$141.00
1000 g Class 2 TR8228 Optional - click here ± 5 mg
$113.00
500 g Class 2 TR8232 Optional - click here ±2.5 mg
$93.00
400 g Class 2 TR8234 Optional - click here ±2.5 mg
$100.00
300 g Class 2 TR8236 Optional - click here ±1.5 mg
$77.00
200 g Class 2 TR8238 Optional - click here ±1.0 mg
$71.00
100 g Class 2 TR8244 Optional - click here ±0.5 mg
$60.00
50 g Class 2 TR8252 Optional - click here ±0.25 mg
$55.00
20 g Class 2 TR8256 Optional - click here ±0.1 mg
$55.00
10 g Class 2 TR8258 Optional - click here ±0.074 mg
$58.00

(7-10 days lead time for all calibration weights and mass sets)

50 LB Cast Iron Test Weight

Quality Guaranteed by the Toughest Standards of All… Our Own.

Designed for scale calibration, our solid cast iron test weights are sealed to ASTM classes 6 and 7 specifications; Class F tolerances are listed in the National Institute of Standards and Technology Handbook 105-1.  All weights are traceable to NIST.  To verify adherence to class F tolerances, OPTIONAL traceable certificates are available for an additonal $75.00. 

Our cast iron weights undergo a special phosphatizing process in which the metal is thoroughly cleaned and mildly etched to allow exceptional finish adhesion.  The weights are then coated with a layer of chip-resistant paint which conforms to NIST Handbook 105-1 standards.  This two-step process ensures a long-lasting finish that greatly reduces the possibility of corrosion.
Complete Listing of all Available Cast Iron Grip Handle Weights
WITHOUT traceability certificate
Nominal
Value
Class Tolerance Part Number Weight Dimensions Price
1lb Class 7 ± 210 mg 12876 1.63" x 2.63" x 1.25"
$50.00
2 lb Class 7 ± 300 mg 12874 2.06" x 3.13" x 1.63
$60.00
5 lb Class 7 ± 750 mg 12823 2.63" x 4" x 3"
$65.00
10 lb Class 7 ± 1 g 12828 3.25" x 5" x 3.88"
$84.50
20 lb Class F ± 1 g 12870 5.87" x 4.5" x 5"
$109.90
25 lb Class F ± 1.1 g 12833 4.38" x 6.63" x 4.93"
$133.90
50 lb Class F ± 2.3 g 12839 5.63" x 7.88" x 6.38"
$146.90
5 kg Class 7 ± 1.4 g 12786 3.25" x 5.38" x 4"
$80.00
10 kg Class F ± 2.2 g 12767 4.5" x 6" x 4.94"
$100.00
20 kg Class F ± 2.0 g 12771 7.75" x 5.63" x 5.88"
$128.70
25 kg Class F ± 2.5 g 12775 5.38" x 8" x 7"
$170.00
All calibration weights are not returnable.  Once your order has been placed it CAN NOT be cancelled.  Please carefully consider this prior to placing your order.  The reason for this is these weights are custom manufactured and are certified on the date they were made.  In addition, if you touch the calibration weight with your fingers the oil in your skin would change the tolerance and we can not take this chance if the weight was returned.

avoirdupois weights
Calibration weights - all tolerances stated in milligram (mg) Statement Of Accuracy included
Note Traceable or NVLAP calibration certificate available AT ADDITIONAL COST
Nominal
Value
Class Part Number Certification Tolerance Price
50 lb grip Class F TR1276 Optional - click here ± 2.3 g
$727.00
30 lb grip Class F TR1275 Optional - click here ± 1.4 g
$570.00
25 lb grip Class F TR1274 Optional - click here ± 1.1 g
$483.00
20 lb grip Class F TR1272 Optional - click here ± 910 mg
$437.00
10 lb grip Class F TR1270 Optional - click here ± 450 mg
$266.00
10 lb Class F TR1201 Optional - click here ± 450 mg
$173.00
5 lb Class F TR1203 Optional - click here ± 230 mg
$112.00
2 lb Class F TR1209 Optional - click here ± 91.0 mg
$69.00
1 lb Class F TR1211 Optional - click here ± 70.0 mg
$50.00
12 oz Class F TR1212 Optional - click here ±70.0 mg
$42.00
8 oz Class F TR1213 Optional - click here ±45.0 mg
$40.00
4 oz Class F TR1215 Optional - click here ±23.0 mg
$35.00
2 oz Class F TR1217 Optional - click here ±11.0 mg
$32.00
1 oz Class F TR1220 Optional - click here ±5.4 mg
$30.00
1/2 oz Class F TR1222 Optional - click here ±2.8 mg
$29.00
1/4 oz Class F TR1224 Optional - click here ±1.7 mg
$22.00
1/8 oz Class F TR1226 Optional - click here ±1.3 mg
$22.00
1/16 oz Class F TR1228 Optional - click here ±1.1 mg
$23.00

(7-10 days lead time for all calibration weights and mass sets)

calibration weights
Certified Calibration Weights
  • 1 mg to 30 kg weights.  Sold individually or as a weight sets.
  • All weights meet or exceed ASTM specifications
  • All mass measurements are made using procedures developed by NIST
  • All mass standards are milled from the finest corrosion-resistant stainless steel stock ensuring consistent density
  • Each weight is calibrated by a NVLAP-accredited metrology lab in a climate-controlled environment
  • One-piece construction provides the maximum mass stability
  • Each weight and weight set is supplied complete with a Certificate of Traceability
  • Certificate of Calibration is available at an additional cost and must be ordered at time of placing order
  • Each weight is calibrated by a NVLAP accredited metrology laboratory



Single-piece construction: Because the precise measurement of density can only be achieved using a single piece weight, all calibration weights are ASTM Type 1 single-piece weights.  These weights contain no air cavity or foreign adjusting material, thus providing the maximum mass stability.  In addition, it is an ASTM requirement that one-piece weights are used as standards and where mass stability is required.


A Choice of Preconfigured or Custom Weight Sets: Whether you choose a preconfigured weight set, or have a custom set made to meet your specific needs, be assured that all calibration weights are made of the highest quality materials.  Weight sets consist of flat weights in the 1mg to 500mg range and knob-style weights.

The mass standards produced today are designed to meet or exceed the standards of the American Society of Testing Materials (ASTM E617)

Which Class Calibration Weight is Right for My Application?
A balance should be calibrated using a weight with a class tolerance factor greater than the readability of the balance.  Example: A milligram balance with readability of 0.001g (i.e. A&D FX-300i - 320g x 0.001g) may be calibrated with a weight having a known tolerance of at least 0.0009g.

OIML E2 and Ultra Mass Class U
Mass Standards.  These mass standards provide the greatest precision we offer.  They are ideal for use as reference standards to calibrate other weights or for calibrating high-resolution analytical balances.  Ultra Mass weights are identical to E2 weights except for the nominal value markings.  E2 weights have no markings on the weights, many customers prefer the weights be marked with the nominal value.  The OIML E2 tolerance is approximately two times the precision of ANSI/ASTM Class 1.

ANSI/ASTM Class 1
can be used as reference standard in calibrating other weights and appropriate for calibrating high-precision analytical balances (from 0.01mg to 0.1mg).

ANSI/ASTM Class 2 Appropriate for calibrating high-precision toploading balances with readabilities ranging from 0.001g to 0.01g.

ANSI/ASTM Class 3
Appropriate for calibrating balances with moderate precision, ranging from 0.01g to 0.1g.

ANSI/ASTM Class 4
Appropriate for student use and semi-analytical weighing.

NIST Class F
Used to test commercial weighing devices by state and local weights and measures officials, device installers and service technicians. Class F weights may be used to test most accuracy class III scales, all scales of class III L or IIII, and scales not marked with a class designation.


Are all weights marked? YES

Small Knob weights marked with nominal values (100g,50g,20g......)

OIML shape marked with the nominal values (5,2,1,500,200,100,20,10..........) no gram designation


Do the calibration weights come with a specified due date for recalibration? NO

ISO/IEC 17025 paragraph 5.10.4.4 States: " A calibration certificate (or calibration label) shall not contain any recommendation on the calibration interval except where this has been agreed with the client.'  Therefore,we do not provide a calibration due date.  Setting calibration interval is the responsibility of the end user.  The certificate includes guidance information in the proper recertify cycle depending upon the use of the calibration weights.


Difference between Traceability and Cert of Calibration?

The major difference between the Report of Traceability and the Calibration Certificate is the Report of Traceability is a tolerance test and is only available for new weights.  The Certificate of Calibration is a full report of the parameters tested.  Below we outline what comes with each report.


Report of Traceability.
Each Ultra Mass , Class 1, Class 2 weight or weight set is supplied with a report of traceability at no additional cost.  This report identifies:

  • Tolerance class
  • Type of construction
  • NIST test number
  • Date of applicable primary standard(s)
  • Secondary set number
  • Includes technician's signature
  • Description of the weight(s)
  • Test Number
  • Serial Number
  • Nominal Value
  • Uncertainty of the measurement tolerance
  • Information on weighing procedures
  • Date the primary standards were last tested at NIST and the NIST test number
  • Date and test number for our working standards.
  • Statement of traceability to the International Prototype Kilogram (IPK) this meets the international requirement for traceability to the International System of Units.


Certificate of Calibration
Certificate of Calibration are available for any Ultra Mass, Class 1, or Class 2 weight or weight set.  The "W" at the end of the part number designates a Certificate of Calibration will be included with your weight(s).  The Certificate of Calibration includes everything found in a Report of Traceability listed above with the additional information listed below:

  • Uncertainty value
  • Test conditions temperature, barometric pressure, humidity.
  • Conventional Mass Correction
  • Uncertainty of the measurement
  • Identification of the balance used in the calibration
  • as found value if an adjustment is performed
  • assumed density of the weight
  • material weight is made from
  • Pass/Fail result of magnetic testing
  • Volume of the weight
  • Cubical Coefficient of expansion
  • True Mass correction


Who do you feel needs a Calibration Certificate verses Report of Traceability?

If you are under ISO, FDA or other regulation they should get a Calibration Certificate.  Also, anyone that plans to calculate uncertainty for their own process would need the certificate of calibration so they could correctly include our uncertainty into their own uncertainty budget.

If they have a balance or scale with the ability to read to a milligram or better it is always recommend they know the corrected value of the weight and this is only available with the Calibration Certificate.


Recertification Service
Weight values can change over time due to scratches, fingerprints, wear and even corrosion resulting from atmospheric contaminants.  Regular checks on the accuracy of mass standards ensures the accuracy of measurements.  We have access to mass metrology lab providing this service at a very competitive prices. 

The rates vary depending upon the size of the weight (1 gram cost less than a 5kg weight) are listed below and subject to change.  Typical turn around time (excludes transit time) is 7 to 10 business days upon receipt at the metrology lab.  You are responsible for both in and out bound freight and insurance costs.

  • Single weights - 1g - $44 , 5kg - $144
  • Weight sets depend upon the amount of weights in a set - 21 piece set 1mg - 100g - $854

Please call us for up to date pricing and the procedure involved in sending your weights in for recertification.


What does calibration of a laboratory weight entail?

All calibrations are accredited calibrations performed using weights by NIST weighing designs, where all weights are compared against 2 standards.  The mass comparators used for performing the calibration ascertain and measure differences to 10, 1, and even 0.1 micrograms (one ten-millionth of a gram).  The value of the unknown weight is computed using a least sum squares technique by the NIST masscode software.  The software performs statistical checks on the balance performance and the computed values of the second standard.  If the balance performance or computed value of the second standard are found to be unacceptable the software requires that the measurement be repeated.  It is only when the process standard deviation and computed value of the check standard are acceptable that metrologist is confident in the value for the customer's weight.  All measurements in metrology laboratory, including tolerance testing, use this Echelon I weighing technique.  The weighing designs are the same ones developed and used by NIST.  All measurement results are traceable to the International Prototype Kilogram (IPK) through a NIST calibration of our primary standards.

Calibration technicians must wear appropriate static free clothing, as well as gloves, hair nets and face masks, to reduce the possibility of contamination (and changing the weight of the weights) from skin oils, hairs, or airborne droplets.  Calibration weights are never touched directly by human hands.


What is True Mass Correction?

Basically, the only people who use "True Mass" are calibration laboratories and other people who apply air buoyancy corrections to the measurements.  Conventional mass is what a weight would weigh at sea level at standard temperature and pressure.  Since most people use their weights in air and don't have the equipment or desire to measure and calculate the air density they have no need for the true mass values.  NVLAP published NIST Handbook 150-2G requiring calibration certificates to reporting "true mass".  If someone needs true mass they typically will know how to calculate it from the Conventional mass.


What is Uncertainty?

Uncertainty is more than just the repeatability of the balance it is a summation of all things which contribute to the error in the measurement process.  Uncertainty is the root sum square of balance deviation, repeatability on the check standard, variability in the density of the standard, variability in the density of the weight under test, variability of the temperature, variability of the barometric pressure, variability of the humidity, operator skill and the uncertainty of the standard used multiplied by two.


What is the difference in tolerance between Ultra, Class 1, Class 2 and other calibration specifications?




Metric Weight Tolerances - all tolerances stated in milligram (mg)
  American Society of Testing & Measurement ASTM E617 International Organization of Legal
Metrology Recommendation R111
Denomi-
nation
Metric
Ultra Class Class 1
mg
Class 2
mg
Class 3
mg
Class 4
mg
Class 5
mg
Class 6
mg
Class 7
mg
  E1
mg
E2
mg
F1
mg
F2
mg
M1
mg
M2
mg
M3
mg
5 kg 6.00 12 25 50 100 250 500 1400   2.5 7.5 25 75 250 750 2500
3 kg 3.80 7.5 15 30 60 150 300 1000                
2 kg 2.50 5.0 10 20 40 100 200 750   1.0 3.0 10 30 100 300 1000
1 kg 1.25 2.5 5.0 10 20 50 100 470   0.5 1.5 5 15 50 150 500
500 g 0.600 1.2 2.5 5.0 10 30 50 300   0.25 0.75 2.5 7.5 25 75 250
300 g 0.380 0.75 1.5 3.0 6.0 20 30 210                
200 g 0.250 0.50 1.0 2.0 4.0 15 20 160   0.1 0.30 1.0 3.0 10 30 100
100 g 0.125 0.25 0.50 1.0 2.0 9 10 100   0.05 0.15 0.5 1.5 5 15 50
50 g 0.060 0.12 0.25 0.60 1.2 5.6 7     0.030 0.10 0.30 1.0 3.0 10 30
30 g 0.037 0.074 0.15 0.45 0.90 4.0 5 44                
20 g 0.037 0.074 0.10 0.35 0.70 3.0 3 33   0.025 0.080 0.25 0.8 2.5 8 25
10 g 0025 0.050 0.074 0.25 0.50 2.0 2 21   0.020 0.060 0.20 0.6 2 6 20
5 g 0.017 0.034 0.054 0.18 0.36 1.3 2 13   0.015 0.050 0.15 0.5 1.5 5 15
3g 0.017 0.034 0.054 0.15 0.30 0.95 2 9.4                
2 g 0.017 0.034 0.054 0.13 0.26 0.75 2 7.0   0.012 0.040 0.12 0.4 1.2 4 12
1 g 0.017 0.034 0.054 0.10 0.20 0.50 2 4.5   0.010 0.030 0.10 0.3 1.0 3 10
500 mg 0.005 0.010 0.025 0.080 0.16 0.38 1 3.0   0.008 0.025 0.08 0.25 0.80 2.5  
200 mg 0.005 0.010 0.025 0.060 0.12 0.26 1 1.8   0.006 0.020 0.06 0.20 0.6 2  
100 mg 0.005 0.010 0.025 0.050 0.10 0.20 1 1.2   0.005 0.015 0.05 0.15 0.5 1.5  
50 mg 0.005 0.010 0.014 0.042 0.085 0.16 0.5 0.88   0.004 0.012 0.04 0.12 0.4    
20 mg 0.005 0.010 0.014 0.035 0.070 0.12 0.5 0.56   0.003 0.010 0.03 0.10 0.30    
10 mg 0.005 0.010 0.014 0.030 0.060 0.10 0.5 0.4   0.002 0.008 0.025 0.08 0.25    
5 mg 0.005 0.010 0.014 0.028 0.055 0.080 0.2     0.002 0.006 0.020 0.06 0.20    
2 mg 0.005 0.010 0.014 0.025 0.050 0.060 0.2     0.002 0.006 0.020 0.06 0.20    
1 mg 0.005 0.010 0.014 0.025 0.050 0.050 0.1     0.002 0.006 0.020 0.06 0.20    
The table above is a listing of the tolerances of various classes of masses.  The weight value can deviate above or below the nominal value by the tolerance defined.  To determine the tolerance of a mass, look at the denomination or nominal value of the weight and the appropriate class you need.
Custom weight sets are available upon request by calling
Precision Weighing Balances at 978-521-7095
All calibration weights are not returnable.  Once your order has been placed it CAN NOT be cancelled.  Please carefully consider this prior to placing your order.  The reason for this is these weights are custom manufactured and are certified on the date they were made.  In addition, if you touch the calibration weight with your fingers the oil in your skin would change the tolerance and we can not take this chance if the weight was returned.



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