Meriam 50MK10 Laminar Flow Element

Meriam Laminar Flow Elements (LFE) are ideal for measuring low gas flow rates from 0.2 SCCM to 2250 SCFM. They offer inherent accuracy and repeatability and are calibrated in our ISO17025-accredited flow laboratory, traceable to NIST. With a turndown of 20:1 or less, the differential pressure generated is nearly linear with flow. This combination makes LFE the optimal choice for gas flow measurement and flow control applications.

Performance

Standard LFE calibration accuracy is ±0.72% of reading (not a percentage of full scale), traceable to the National Institute of Standards and Technology (NIST). The rugged construction and absence of moving parts ensure stable LFE calibration. Only physical damage or particulate buildup within the element can cause calibration drift.

Standard Accuracy: ±0.72% to ±0.86% of reading

Repeatability: 0.1

Response Time: 16 milliseconds

Turndown: 20:1 achievable with precise DP devices; higher turndown possible with advanced DP instrumentation

Utility

The Meriam 50MK10 Laminar Flow Element can be used to measure flow rates for a variety of gases and applications. Standard models measure air flows as low as 0.2 SCCM (5.9 E-06 SCFM) up to 2250 SCFM under standard conditions. Custom models are available for air flows up to 15,000 SCFM. Stainless steel or aluminum construction makes LFE compatible with most gases. Flow rates for gas mixtures can also be measured when the percentage of component gases and mixture properties are known.

Applications

LFE is suitable for most clean, non-condensing gas flow applications. They excel in critical gas flow measurement applications and serve as excellent calibration standards due to their inherent accuracy, stable calibration, excellent response time, and repeatability. LFE is used to calibrate turbine meters, variable area flowmeters, flow regulators, mass flow meters, thermal anemometers, and more. Gas flow measurement for demanding flow control is a common application. Other applications include leak detection and quantification, design and testing of discrete components, automotive engine and emissions testing, and door/window leakage testing.

LFE Matrix

The LFE matrix can be constructed from individual stainless steel tubes or wound stainless steel foil. These tubes are sufficiently long relative to their inner diameter to ensure laminar flow within each tube. The result is a near-linear relationship between differential pressure and flow rate. The differential pressure generated across the matrix responds very quickly to changes in flow. All differential pressure represents a permanent pressure loss to the system, but LFE is sized to produce no more than 8 inches of water column at maximum flow conditions. The individual tube diameters are very small, so the flowing gas must be clean and dry to maintain calibration. Filtered inlet versions are available for most LFE models to keep the matrix clean and calibration constant.

Calibration and Measurement

Meriam LFE are calibrated using air under reference conditions of 29.92 inches of mercury absolute (760 mm Hg) and 70°F (21.1°C). Each finished element is calibrated traceable to the National Institute of Standards and Technology. Meriam LFE provide repeatable flow curves based on SCFM versus inches of water differential pressure. Correction factors are included to cover an absolute pressure range of 26 to 36 inches of mercury and an inlet temperature range of 50°F to 150°F. For special flow applications, we request that you contact Meriam with complete flow information. The rated accuracy* for all Meriam LFE is a percentage of the actual reading—not the larger percentage of full-scale flow tolerance typical of other devices.