There are many benefits to using Thermal Mass Gas Flow Meters over other flow measurement technologies.
Flow measurement of gases
THERMAL MASS FLOW
Direct mass flow measurement of air and gases in standard volumetric units (ie SCFM or NM3/H) or mass units (ie LBS/M or KG/H). Each meter has the option for the user to select a variety of flow units (see model data sheets for specific flow units available).
OTHER TECHNOLOGIES
Other technologies require multiple instruments to determine the volumetric flow rate at reference conditions.
Pressure or temperature compensation
THERMAL MASS FLOW
No additional pressure or temperature compensation is required. This is a time and cost saving measure. No additional calculations or equipment are needed to calculate flow because the meter measures the mass flow rate. Some models offer a second 4-20mA output that can be programmed to measure temperature or flow.
OTHER TECHNOLOGIES
Differential pressure flow meters require pressure and temperature compensation.
Turndown
THERMAL MASS FLOW
Repeatability and exceptionally broad measurement range: up to 1000:1 (100:1 typical). Whether the flow is at a very high or low velocity, thermal mass flow meters can measure it.
OTHER TECHNOLOGIES
Vortex meters are only suitable for very high flow rates.
DP meters do not have good turndown.
Pressure Drop
THERMAL MASS FLOW
Low pressure drop. The pressure drop of a thermal mass flow meter is negligible.
OTHER TECHNOLOGIES
If a DP meter is used to measure low velocity flow, a very small orifice is required resulting in high pressure drop.
Moving Parts
THERMAL MASS FLOW
No moving parts.
OTHER TECHNOLOGIES
A meter with moving parts, like a Turbine meter, will need regular maintenance.
Price
THERMAL MASS FLOW
Cost effective. Thermal mass flow meters offer a low cost alternative.
OTHER TECHNOLOGIES
Ultrasonic meters are especially expensive.
Installation
THERMAL MASS FLOW
Easy to install. Insertion (all Fox models) and inline (FT2A/FT3 models only) configurations. Insertion meters are easy to install, inline meters come equipped with flow conditioners to help reduce the straight run requirements. Communication options available and intrinsic to meter electronics.
OTHER TECHNOLOGIES
Some meter technologies are complicated and difficult to install, require additional equipment, or long straight pipe run requirements.
Operation
THERMAL MASS FLOW
Microprocessor based, field rangeable electronics. Fox pioneered the use of microprocessors in thermal mass flow meters and continues to create innovative solutions to measurement needs across many industries and applications. Gas-SelectX, available in some Fox models, allows the user to change the gas selection in the field. Displays with configuration panels and free software allow users to interact and program the meter in the field.
OTHER TECHNOLOGIES
Most manufacturers build meters for a single purpose, gas calibration, or application. The customer must sift through pages of specs to find the right meter for their application. This is time consuming and ineffective.