Gas Flow Calibration
ISO 17025 Gas Flow Calibration Services by Graftel
| Rotometer Calibration Air and Gases |
Laminar Flow Element Calibration |
Flowmeter Calibration Air and Gas |
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| Sonic Nozzle and Sonic Choke Calibration | ||
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Graftel maintains five NIST traceable primary gas flow calibration systems. Flow rates between 1sccm up to 1,500 slm are measured. The pressure range is 0 to 1000 psig, (0 to 69 bar). Each system can achieve uncertainties up to 0.2% of reading. Air or gas or mixture of gasses may be used. This includes flammable gasses.
Graftel can also perform these calibrations at your site.
Gas Flow Calibration Services Include
All flow calibrations completed by Graftel come with:
- A NIST traceable and ISO 17025 accredited certificate
- All corresponding test data
- Unit inspection/service testing
- 5 Business days or less turnaround
Listed below is a small sampling of the types of equipment we can perform flow calibrations on in our labs.
Digital RH Meter |
Turbine Meters |
Manufacturers we have Calibrated
Graftel's labs have worked with hundreds of name brand and sometimes not-so-name brand flow meters and gauges, we specialize in working with you to keep your valuable equipment calibrated. Listed below is a a small sampling of some of the manufacturers we complete flow calibration's with on a regular basis.
If you don't see the manufacturer of your equipment here, don't panic! Contact us with your information and we'll take care of the rest.
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Great Plains Industries Brooks Brooks "SMART" meters Dwyer Omega Aalborg Flow Technology Foxboro Panametrics Fischer - Porter MEM Yokogawa Gilmont Flocat Hedland Eldridge Products FTI TSI |
Solomat Alnor Sierra Hedland Meriam Cosa Schutte & Koerting Draeger JLC Fox Valve Alicat Scientific UFM ATC Vaisala Victor Shaw MKS Flow Jewett |
Hastings General Eastern Blue-White Industries Madgetech American Meter Company Eqimeter Conbraco Kurz Testo Sper Scientific Davis Graywolf Cole-Parmer Fischer Scientific Ertco Millipore ...And MANY More! |
Gas Primary A
This system's flow rate range is 0.06 to 6 sccm, (0.00012 to 0.012 scfh). The pressure range is 0 to 1000 psig, (0 to 124 bar). The primary standard used is a Brooks mercury sealed flow tube. The system's secondary standard is a laminar flow element. The uncertainty in mass flow rate is up to 0.20% of reading.
Gas Primary B
This system's flow rate range is 3 to 140 sccm, (0.005 to 0.3 scfh). The pressure range is 0 to 1000 psig, (0 to 124 bar). The primary standard used is a Brooks mercury sealed flow tube. The system's secondary standard is a laminar flow element. The uncertainty in mass flow rate is up to 0.20% of reading.
Gas Primary C
This system's flow rate range is 0.05 to 3 slm, (0.1 to 6 scfh). The pressure range is 0 to 1000 psig, (0 to 124 bar). The primary standard used is a Brooks mercury sealed flow tube. The system's secondary standard is a laminar flow element. The uncertainty in mass flow rate is up to 0.20% of reading.
Gas Primary D
This system's flow rate range is 2 to 88 slm, (4 to 186 scfh). The pressure range is 0 to 1000 psig, (0 to 69 bar). The primary standard used is a Brooks mercury sealed flow tube. The system's secondary standard is a laminar flow element. The uncertainty in mass flow rate is up to 0.20% of reading.
Gas Primary E
This system's flow rate range is 23 to 1168 slm, (1 to 41 scfm). The pressure range is 0 to 1000 psig, (0 to 69 bar). The primary standard used is a sonic nozzle. The system's secondary standard is a laminar flow element. The uncertainty in mass flow rate is up to 0.20% of reading.
Rotometer Calibration in liquids and gases ISO 17025 and NIST traceable

Rotameters are a gauge that consists of a graduated glass tube containing a free float for measuring the flow of a fluid or gas. Usually a rotameter will have a tube that holds a pellet or cylinder that will move up the scale according to the pressure from the gases or liquids it is measuring.
During its use, a rotameter will accumulate foreign material inside and will eventually lose its sensitivity to measurement. In many cases, a yearly rotometer calibration will keep your measurements accurate and save you time and money in maintenance. Graftel's, calibration lab has calibrated Rotameters from dozens of manufacturers, and we have established yearly rotometer calibration schedules with many of our clients. listed below are several that we have calibrated to NIST accuracy and ISO 17025.
As for services, Graftel can have your liquid or gas Rotameter calibrated and returned to you in 5 business days or less! Graftel also offers ISO 17025 Gas-flow calibrations for your rotometer that are NIST traceable. For more information about our ISO 17025 calibration capabilities, feel free to read our certificate and scope or contact us with your questions.
- Dwyer Instruments VA Series Rotometers
- Omega Instruments FL Series Rotometers
- Universal Flow Instrument Rotameters
- Brooks Instrument Rotameters
- Meter Equipment Manufacturing Rotameters
- Cole Parmer Rotameters
- King Instruments Rotometers
- Blue-White Rotometers
- Kytola Rotometers
Contact Us today if you have a rotameter that needs a NIST traceable ISO 17025 calibration.
Laminar-Flow Element Calibration
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Laminar flow element (LFE's) calibration is a high accuracy job that few flow calibration facilities can perform. The volumetric flow rate is determined by creating a pressure drop across a unique internal restriction, known as a Laminar Flow Element, and measuring differential pressure across it. The restriction is designed so that the gas molecules are forced to move in parallel paths along the entire length of the passage; hence Laminar (streamline) flow is established for the entire range of operation of the device. Unlike other flow measuring devices, in laminar flow meters the relationship between pressure drop and flow is linear.
Our facility not only has the capability to calibrate your laminar flow elements, but since we build our own portable flow standards and local leak rate monitors, our experience isn't only in calibration!
We have calibrated laminar flow elements manufactured by:
- Meriam Instruments
- Furness Controls
- CME Flowmeters
- Hastings Flow Products
- Alicat Scientific
If your manufacturer isn't listed above, contact us with your product information and we'll send you a quote!
Sonic Nozzle and Sonic Choke Calibration and manufacturing services

Graftel has become a reseller and calibration source for Fox Valve! This means that we can now bring your calibrated sonic nozzles and calibrated sonic chokes at a very competitive price! Contact a Graftel Representative today to receive a quote on a calibrated sonic choke! Fox valve also is a manufacturer of:
- Venturi Flow Controls - Includes all venturi products used to measure or regulate flow rates.
- Fuel Cell Ejectors - Fox venturi ejectors have been used in fuel cells since 1985.
- Natural Gas Vapor Recovery Ejectors - The use of Fox ejectors range from small sampling mini-eductors to five-stage vacuum systems.
- Solids Conveying Eductors - for pneumatic conveying of powders, pellets, and bulk solids.
Critical flow nozzles, also called sonic chokes, have been used to maintain stable gas flow rates in systems where maintaining stable, accurate gas flow rates is essential to overall system performance. By establishing a shock wave in the venturi, the sonic choke establishes fixed flow rates unaffected by P or any fluctuations, surges, or changes in downstream pressure. With no moving parts, sonic chokes provide the simplest and most reliable way to regulate gas flows. This is particularly true when high pressure, high temperature, cryogenic, explosive, or high purity gasses need to be regulated.
Industry uses many different names to describe this equipment. Here is a partial list of descriptions that can be used interchangeably:
- Sonic chokes
- Laval Nozzles
- CVM (Critical Venturi Meters)
- Sonic nozzles
- Critical Flow Venturies
Sonic chokes are converging/diverging nozzles whose operating principles are discussed in every fluid mechanics textbook. They offer the designer a remarkably simple way to regulate stable gas flow rates.
Contact a Graftel Representative today to learn more about purchasing a Calibrated Sonic Choke or Sonic Nozzle.









