Exam - Professional - LPG

LPG and Anhydrous Ammonia Liquid Meters

The NCWM Professional Certification Program provides assurance that an individual has a working knowledge of the U.S. standards for weights and measures as adopted by the NCWM. Certification is available to any individual, whether from the public or private sector whose profession requires thorough understanding of the national weights and measures standards. The LPG and Anhydrous Ammonia Liquid Meters certification exam will draw on relevant portions of Handbook 44 and Handbook 112.

LPG and Anhydrous Ammonia Liquid Meters

LPG and Anhydrous Ammonia Liquid Meters

Member $0.00
Non-Member $120.00



Format and Duration:

  • Handbook 44 is available here.

The examination consists of three timed sections and will include a total of 34 questions as described below.  All four sections of the exam must be completed in one session and the candidate may not log off and return to the exam at a later time.  Each section must be completed before moving to the next section of the exam.  Once a section has been completed, the individual may not return to a previously submitted section.

You will be required to perform calculations as part of the exam.  You may bring a calculator into the exam with which you are familiar, or use one provided by the proctor.  Calculators with memory functions are acceptable but programmable calculators are prohibited.  If you use the calculator provided by the Proctor, it is your responsibility to familiarize yourself with its operation before beginning the exam.

The exam is OPEN BOOK.  The proctor will provide you with the following items for this exam, except as specifically noted below:

· A clean copy of the current edition of Handbook 44 and a clean copy of EPO 26 - Liquefied Petroleum Gas (LPG) Liquid-Measuring Systems. If hard copies are not provided you will be permitted to access the NCWM authorized pdf file containing pertinent sections of Handbook 44 and the EPO for this test.

  • A clean copy of NCWM LPG Exam Reference Tables.  These tables are to be used to perform the proving calculations.  Candidates are not to write in or mark this document.
  • Several blank copies of the Report Form from the NCWM LPG Exam Reference Tables.  Candidates may use these forms in performing calculations.  Note: A candidate may bring multiple blank copies of their state’s LPG report form provided it is marked with the state logo.
  • Scrap paper for notes and calculations.
  • All materials provided by the proctor (and all copies of the report forms provided by the candidate) must be returned to the proctor upon completing the exam.  All scrap paper and forms written on by the candidate will be shredded.

The examination is to be taken alone, without assistance from any other individual.

Test instructions are provided online prior to starting the exam.  Since the test is electronically graded, the answer must be marked or typed correctly.  The test questions will be either multiple choice, short answer or compliance/citation format.  For multiple-choice questions, you will be asked to pick the best answer from four options by clicking the button before your selected answer.  For short answer questions, you must enter the specific answer, typed correctly.  For compliance/citation questions, you will be given information describing a situation and asked to assess compliance. A nswer “yes” if the situation complies based on the information provided, otherwise provide the specific legal citation if the device does not comply.  The form of the citation will typically be something like S.X.X. for a specification, T.X.X. for a tolerance, or UR.X.X. for a user requirement.  There is a short practice test to familiarize you with the exam environment and ensure that these basic rules for responses are understood.

Subject of Examination:

1.  Module 4.2 Introduction to Device Control 
and Module 4.4 Dynamic Measuring Systems - General  |  15 questions (30 minute time limit)
These questions test for knowledge, understanding, and ability to apply the basic requirements applicable to all weighing and measuring devices. This may include questions on the selection, care and use of standards, the legal basis of NIST Handbook 44, the organization of that Handbook, understanding of Fundamental Considerations, knowledge of systems of measurement units, understanding and application of General Code requirements, and understanding of the NTEP program and Certificates of Conformance. These questions also test for knowledge and understanding of the general requirements for dynamic liquid measuring devices specified in NIST Handbook 44. This includes knowledge of the technologies used in liquid measuring devices, ability to operate measuring devices and interpret markings and indications, ability to apply appropriate technical and user requirements, and ability to select appropriate tests, perform those tests and apply the tolerances.

2.  Module 4.4.8 LPG and Anhydrous Ammonia Liquid Meters  |  12 questions (30 minute time limit)
These questions test for knowledge and understanding of the basic technologies used in LPG and anhydrous ammonia liquid meter systems, understanding the specific properties of these liquids, understanding of and ability to apply technical and user requirements from NIST Handbook 44 LPG and Anhydrous Ammonia Liquid-Measuring Devices Code to these meter systems, and ability to conduct prescribed tests and properly apply tolerances.

3. Data Reduction for LPG or Anhydrous Ammonia Meter Tests  | 3 questions (30 minute time limit)
These questions test for ability to accurately perform manual calculations to determine delivery errors from raw data from tests of LPG meters.  The questions will require you to calculate the delivery error (calculated in %).  For this exam, percent error is calculated as (prover – meter) / prover x 100.  You will perform calculations either for one set of tests with an electronic digital register or for one set of tests with an analog register.  You will be asked to compute three delivery errors,  1) for the normal net error (normal compensated),  2) for the normal gross error (normal uncompensated) and  3) for the special gross error (special uncompensated), each accurately rounded to two decimal places.  When entering the answer include the sign + or – and include the leading zero if the number is less than 1, but do not enter the % sign, e.g. +0.85 or -0.85.

You will be provided with copies of the NCWM LPG Exam Reference Tables and copies of a report form based on current NIST OWM LPG Training Materials.  You may use this report or your jurisdiction’s report form in doing calculations.  All copies must be returned to the proctor at the end of the exam. You may download a copy for practice.  The Addendum contains a collection of pertinent tables that are used in LPG proving.  This includes tables for the product (only LP s.g. 0.505 will be used) and tables for the pressure and temperature correction for the multiple provers used in the exam.  The candidate must ensure they use the corresponding tables for the specific prover referenced in the test data.  Two samples of test data for the official test, in the form it will be presented for the exam, are shown below.

Data Format for System with an Electronic Digital Register

Meter TypePositive Displacement
Meter RatingMax 100 gpm, Min 20 gpm

Register TypeDigital Electronic
Incrementby 0.1 gal @ 60 oF
Prover IDNCWM-100LCS
Prover MaterialLow Carbon Steel
Prover CoE (/oF)0.0000186
Test Draft12
Test TypeNormal - compensated and uncompensatedSpecial - uncompensated
Observed Flow Rate gpm7225
Meter Temp (oF) @ 1/35658
Meter Temp (oF) @ 2/3
Meter Reading Net (gal)101.0N/A
Meter Reading Gross (gal)100.7101.3
Prover Temp (oF)5657
Prover Pressure (psig)9595
Prover Reading (gal)100.35100.85

Data Format for a System with a Mechanical Analog Register

Meter TypePositive Displacement

Meter RatingMax 100 gpm, Min 20 gpm

Register TypeAnalog Mechanical

Incrementby 0.1 gal @ 60 oF)

Prover IDNCWM-100SS

Prover MaterialStainless Steel

Prover CoE (/oF)0.0000265
Test Draft123
Test TypeNormal - compensatedNormal - uncompensatedSpecial - uncompensated
Observed Flow Rate gpm676527
Meter Temp (oF) @ 1/3
Meter Temp (oF) @ 2/3
Meter Reading Net (gal)100.6N/AN/A
Meter Reading Gross (gal)N/A100.1100.1
Prover Temp (oF)545456
Prover Pressure (psig)909090
Prover Reading (gal)99.85100.60101.05

Passing Score and Grading:

  • 70% (21 or more correct answers)
  • To protect the integrity of the test questions, NCWM will not advise you of the specific questions you answered incorrectly.  The Professional Development Committee will be reviewing incorrect answers in periodic reviews and will adjust scores in select cases if a question is judged invalid.  NCWM will notify you if your score is affected.
  • If you wish to challenge any of the questions, there will be a section at the end of the examination where you can offer comments.  You may also contact the NCWM Professional Development Committee through NCWM via email to info@ncwm.com or call (402) 434-4880.
  • A certification issued under this program is valid for five (5) years.