When working in the gas industry, it is important to establish and maintain rigid standards to help prevent hazards or disasters resulting from faults in the components and fittings used. It is also imperative that the measuring devices used to determine the flow-rates of gas are consistent and precise, since inaccuracies may lead to errors in the way data is collected and the financial implications that arise from this. Meter Testing & Calibration Methodology

 Bell Prover 

The Bell Prover is a primary standard for gas meter calibration. Lloyd Alman performs both calibration and gas tightness testing for domestic and small commercial/industrial meters.

Lloyd Alman has fully automated bell prover systems, which are calibrated against recognised metrological standards, traceable to national standards and housed in a temperature-controlled environment. The gas meters are calibrated on air at pre-selected flow rates with the operation of the Bell Prover system electronically controlled via an easy-to-use software interface developed by LA. This provides flexibility, accuracy and repeatability for testing to a wide range of requirements and presents the test results in a tabular and graphical format.

• Tests all types of domestic meters, including ultrasonic and smaller commercial diaphragm meters
• Well defined data structure compatible with spreadsheet format allows clients to identify trends and early indications of population failure
• Supports an in-service verification programme for a structured meter replacement policy
• Automatically carries out tests at various flow rates and records results
• Accommodates testing to different standards including EN1359
• Verifiable to regulatory authorities

Contaminants Rig 
The contaminants rig is an open loop comparative rig that tests the performance of a single meter when subjected to contamination such as dust or glycols. Meters are usually tested on line natural gas but can also be tested on air or nitrogen. The test gas is passed through two reference meters, one before and one after the meter under test. A number of automatically controlled gas flows are used to observe the meter performance

NGA Rig 
The NGA rig is an open loop comparative rig that can test up to 4 meters at a range of temperatures on different gases. The test gas is passed through two reference meters at room temperature before placement in an environmental cabinet where the gas is passed through a heat exchanger prior to entering the test meters. The environmental chamber can be set to maintain a constant temperature or to follow a predetermined profile. The performance of the meter under test is compared with that of the reference meter.

Air Flow Rig 
The air flow rig is used to test large low-pressure meters and regulators. Conventional meter testing rigs pull air through the meter to measure accuracy. This is considered by many to be the most accurate way to test a meter, but holds one serious drawback in its unsuitability for testing older meters that have been contaminated with oil or debris. The I&C Air flow rig can either pull or push air to test enabling older dirty meters to be tested without risking damage to the internal mechanisms of the rig.

This facility has recently been upgraded to include a new reference meter and pressure transducers. Wiring has also been renewed and bespoke software has been developed to control operating performance. As a result, this facility can produce consistently accurate measurement and computer generated calibration charts for each meter showing a high degree of overlap and repeatability. This facility’s capability ranges from the smallest RPD meters to turbine meters with pipe diameters up to 8 inches.

Standards 
Lloyd Alman can perform meter testing against national (BS 4161) and European metering (EN 1359) standards and has the in-house capability to perform the majority of the testing specified within these standards.