Introducing the Fox FT4A Thermal Mass Flow Meter

The Fox Model FT4A is the newest thermal gas mass flow meter offered from Fox Thermal Instruments.

The Model FT4A measures gas flow rate in standard units (SCFM, NM³/hr, LBS/HR, KG/HR & many more) without the need for temperature and pressure compensation.

A free software tool – FT4A View™ - is available for the Model FT4A that allows the user to connect to and configure the FT4A using a PC or laptop.


Direct Mass Measurement

The Fox Model FT4A measures the mass flow of gases directly in Standard Cubic Feet per Minute (SCFM), Normal Cubic Meters per Hour (NM³/hr), Kilograms per Hour (Kg/Hr), and other mass units without the need for pressure or temperature compensation. One isolated 4 to 20mA output programmable for flow or temperature is standard; HART communication optional. A second output is selectable for pulse or RS485 Modbus RTU.

Outstanding Low Flow Capability, Wide Turn-Down Ratio

The Fox flowmeter is capable of providing precise measurement of extremely low velocity gas flows. This results in a wide measurement range and a turn down ratio up to 1000:1; 100:1 typical.


The non-cantilevered design of the DDC-SensorTM is standard on all Model FT4A flowmeters. Instead of using traditional analog circuitry, the DDC-SensorTM is interfaced directly to the FT4A microprocessor for more speed and programmability.


The Model FT4A has many common gas calibrations pre-programmed into the meter so that the user can select a gas from a list to fit the application. Three gas menus are available: Pure Gas Menu, Mixed Gas Menu, and Oil & Gas Menu.

Probe and Retractor Sizes

The insertion flow meters have a 3/4" robust probe, are easy to install, and can be installed in pipe diameters of 1 1⁄2" to 70". Probe (I) and Retractor (R) sizes are: 6" (06I), 9" (09I), 12" (12I), 15" (15I/15R), 18" (18I/18R), 24" (24I/24R), 30" (30I/30R), and 36" (36I/36R).


The Display and Configuration Panel displays flow rate, flow total, elapsed time (hours since the totalizer was reset), process temperature and alarms. Field configurable variables include flow and temperature engineering units, 4 to 20mA scaling for flow and temperature, standard temperature and pressure (STP), pulse output scaling, zero flow cut off, alarm settings (high flow, low flow, high temp, and low temp), filter setting, and many others.

Digital Communications / FT4A ViewTM

Bus options are RS485 Modbus RTU and HART. The FT4A uses a standard USB port to connect to a PC. Fox's free FT4A ViewTM software provides complete configuration and remote process monitoring functions.

NIST Traceable Calibration

The Fox Calibration laboratory uses NIST traceable flow standards to ensure the highest level of accuracy. A calibration certificate is supplied with every meter.

Discrete Output

The discrete output can be set to provide a signal when alarms are generated.

Enclosure and Area Rating

NEMA 4X enclosure approved for FM and FMc Class I, Division 1; ATEX/IECEx Zone 1 approved. CE mark.

Input Power

Input Power: 12 to 28VDC, 20 watts max. Full Input Power Range: 10 to 30VDC, 20 watts max.

For more information on the FT4A contact Power Specialties at (816) 353-6550 or visit this link for the Power Specialties website.

Power Specialties: Industrial Markets

Established in 1967, Power Specialties was founded on the concept that customer service is of primary importance. Our staff of Sales Engineers are well trained in the application and selection of instrumentation and control products. Specializing in providing instrumentation and control solutions for industry:
  • Ethanol / BioFuel
  • Agricultural and Specialty Chemical
  • Power
  • Pharmaceutical
  • Manufacturing
  • Water/Wastewater
  • Food/Beverage
  • Oil and Gas Production
For more information, visit Power Specialties at or call  (816) 353-6550 .

Rotary and Linear Damper Drives for Control of Combustion Air and Flue Gas

Electric Damper Drive
Electric Damper Drive (Rotork)
Combustion air and flue gas damper drives fill a critical role requiring safety, accuracy and reliability above all else. It is critical to deploy the best drive technology to maximize combustion efficiency, minimize emissions and reduce installation costs.

Damper Operator (Drives) Types :

Damper drives can be one of three types: pneumatic, electric, or electro-hydraulic, as described below.
  • Pneumatic. These damper operators are used whenever controls rely primarily on compressed air (pneumatic) for moving operators.
  • Electric. These damper operators are used whenever controls rely primarily electricity as the power source.
  • Electro-hydraulic. These damper operators are the same as the electric type described above, but also have a hydraulic system to position the damper.
Pneumatic Damper Drive
Pneumatic Damper Drive
(Rotork Type K)
A very important part of damper design is determination of damper torque and sizing and selection of damper actuator for the maximum torque. Actuator torque should be selected to provide the maximum torque required to operate the damper as well as to provide margin and allow for degradation over the life of the damper. Actuators should be evaluated for damper blade movement in both directions, at the beginning of blade movement, and while stroking blades through the full cycle of movement.

The Goal for Selecting the Best Drive Technology:

Reduced emissions, lower fuel consumption and improved boiler draft control.

Ways to achieve this goal:
Installed Damper Drive
Installed Damper Drive
  • High speed continuous modulation of ID/FD fan and inlet guide vanes 
  • Improved modulation and control of secondary air dampers 
  • Improved automation and burner management 
  • Quick response to plant demand 
  • Improved reliability in high temperature environments 
  • Precise damper and burner positioning 
  • Simple commissioning and diagnostics 
  • Low running costs, virtually maintenance free 
  • Pneumatic, analog and bus network communications 
For more information, review the document below, or download it at this link on Power Specialties website.

Basics of Pressure Measurement: Hydrostatic Pressure

pressure transmitter
Pressure transmitter
Pressure measurement is an inferential way to determine the height of a column of liquid in a vessel in process control. The vertical height of the fluid is directly proportional to the pressure at the bottom of the column, meaning the amount of pressure at the bottom of the column, due to gravity, relies on a constant to indicate a measurement. Regardless of whether the vessel is shaped like a funnel, a tube, a rectangle, or a concave polygon, the relationship between the height of the column and the accumulated fluid pressure is constant. Weight density depends on the liquid being measured, but the same method is used to determine the pressure.

A common method for measuring hydrostatic pressure is a simple gauge. The gauge is installed at the bottom of a vessel containing a column of liquid and returns a measurement in force per unit area units, such as PSI. Gauges can also be calibrated to return measurement in units representing the height of liquid since the linear relationship between the liquid height and the pressure. The particular density of a liquid allows for a calculation of specific gravity, which expresses how dense the liquid is when compared to water. Calculating the level or depth of a column of milk in a food and beverage industry storage vessel requires the hydrostatic pressure and the density of the milk. With these values, along with some constants, the depth of the liquid can be calculated.

The liquid depth measurement can be combined with known dimensions of the holding vessel to calculate the volume of liquid in the container. One measurement is made and combined with a host of constants to determine liquid volume. The density of the liquid must be constant in order for this method to be effective. Density variation would render the hydrostatic pressure measurement unreliable, so the method is best applied to operations where the liquid density is known and constant.

Interestingly, changes in liquid density will have no effect on measurement of liquid mass as opposed to volume as long as the area of the vessel being used to store the liquid remains constant. If a liquid inside a vessel that’s partially full were to experience a temperature increase, resulting in an expansion of volume with correspondingly lower density, the transmitter will be able to still calculate the exact mass of the liquid since the increase in the physical amount of liquid is proportional to a decrease in the liquid’s density. The intersecting relationships between the process variables in hydrostatic pressure measurement demonstrate both the flexibility of process instrumentation and how consistently reliable measurements depend on a number of process related factors.

Contact Power Specialties at (816) 353-6550 or visit with any industrial pressure measurement application of requirement.