Issues Regarding Temperature Compensation

1
Issues Regarding Temperature Compensation

• Henry Oppermann
• Weights and Measures Consulting
• NCWM, July 10, 2007

2
History

• 1960 NCWM Presentation, Temperature Compensated
  Meters in LP-Gas Service
• 1965 ATC requirements in H44 LPG Code
• 1974 NCWM State and Industry Technical
  Presentations (Hawaii, Exxon Company)
• Since 1970s, H44 LMD and Cryogenic Codes updated
  to allow temperature compensation for wholesale
  of petroleum products.
• 1979 NCWM Symposium on Temperature Compensated
  Volumes in the Sale of Petroleum Products
• In 1986 Method of Sale for LPG added to NIST
  Handbook 130

3
Temperature Change Needed to Cause1 Change in
Volume

• LP Gas 6 ºF
• Gasoline 15 ºF
• No. 2 Diesel 22 ºF
• Stainless Steel Prover 377 ºF

4
What has Changed Since the 1970s?

• ATC at retail was a major issue in the late 1970s
• Double-wall tanks and above-ground storage
  contribute to temperature variations.
• Larger service stations with increased throughput
  and temperature variations.
• Larger temperature variations in the products

5
Is an ATC Measurement More Accurate than an
Uncompensated Measurement?

• ATC is a more comprehensive measurement
• ATC meter must meet volume accuracy and the
  tolerance on agreement of gross and net values

6
Product Measurement

• An uncompensated meter measures (only) the volume
  of the product at the temperature of the product
  at the time of measurement.
• A temperature compensated meter measures (1) the
  volume of the product and (2) the temperature of
  the product at the time of measurement and
  corrects the volume to the volume the product
  would have at 60 ºF.

7
Is Temperature Significant in Gasoline
Measurement?
Volume change of gasoline due to temperature is a
range of 5 from 30 ºF to 100 ºF.
8
Does a Single Set of VCFs Improve Gasoline
Measurement?
Temperature correction to volume using VCFs for
59 ºAPI gravity reduces the effect of temperature
to a range of 0.3 (an improvement over 1600).
9
Improved Measurement Using the Canadian VCFs
Temperature correction to volume using VCFs for
730 kg/m3 reduces the effect of temperature to a
range of 0.4 (an improvement over 1200).
10
Which VCFs Should Be Used?

• One set of VCFs should be used for gasoline and
  another for diesel fuel
• Can choose values to fit the U.S. market or
• Using Canadas VCFs provide consistency and
  facilitates movement of dispensers across country
  borders (secondary market)
• Ethanol blends and biodiesel must be considered
• Are the expansion characteristics sufficiently
  similar to use the same VCFs?
• Decisions can be made not insurmountable

11
Claim ATC is prohibited because H44 Doesnt
Recognize ATC for VTMs or for RMFDs

• Unless something is specifically prohibited by
  law or regulation, then it is permitted
• Absence of specific H44 requirements does not
  prohibit the use of ATC
• G-A. 3. Special and Unclassified Equipment
  paragraph applies
• Possible restraint of trade issues

12
Claim Cant Have H44 Requirements without a
Method of Sale Requirement

• Nothing prohibits H44 recognition of the
  technology independent of a Method of Sale
  requirement
• LPG Code requirements were in H44 in 1965
• LPG Method of Sale requirement was adopted in
  1986

13
NTEP Policy

• More equipment is subject to weights and
  measures enforcement than is subject to type
  evaluation. The additional equipment is
  controlled through routine field inspections.

14
Claim No ATC system has an NTEP Certificate

• If a company hadnt applied for NTEP evaluation
  of an ATC system, then NTEP states potentially
  could have prohibited it.
• However, NTEP declined to perform an NTEP
  evaluation of an ATC system
• States with their own type evaluation program can
  require state evaluations
• For other states, the acceptability of ATC
  systems is now a field inspection issue.

15
NTEP Doesnt Have Type Evaluation Criteria

• Handbook 44 has ATC requirements for LMD
  wholesale, LPG meters and cryogenic meters
• Existing H44 criteria should be used under G-A.3,
  Special and Unclassified Equipment
• ST recommendations in Item 330-4 are based on
  existing H44 requirements

16
Claim Test procedures dont exist for RMFDs
with ATC

• The test procedure is very similar to that for
  LMD loading rack meters.
• The test procedure is more simple than for LPG
  liquid meter testing

17
Claim Testing will take longer and we need
additional equipment

• The test time will take longer
• Both gross and net displayed in test mode
• Must take temperature at meter for uncompensated
  meter test
• Need (digital) thermometer probes for meter and
  prover temperature wells
• Need calculation software
• Recommend bottom-drain provers with fuel storage
  tanks (for uncompensated meters as well)
• Justification You need these tools. Its your
  job.

18
The NCWM Needs a Plan

• Temperature compensation should be required for
  all transactions
• Precedent Look to past NCWM actions
• Adopt a nonretroactive requirement for new
  equipment
• Have a retroactive date for all equipment, e.g.,
  retroactive in 5 years

19
Costs Versus Benefits

• Is the cost of improved measurement justified to
  station owners and consumers?
• Is ATC a measurement issue or a political issue?
• Is ATC a local issue or a national issue?
• Improved inventory and environmental controls
  improve station management