Application for Rheotherm and RheoVac Instruments

Liquid Low Flow Meters

Rheotherm flow meters are an excellent, and often times the only choice for reliable liquid flow measurement at low flow rates. For flow rates from 1 gallon/year (10 cc/day) to a few GPM, they provide repeatable liquid flow measurement with little or no maintenance. Options for hazardous locations (intrinsically safe/explosion-proof) are available.

Model 210 with displayWhat Can We Measure?
The Intek Rheotherm Model 210 flow meter can be used to measure continuous flow of most homogeneous liquids with low or high viscosity, as well as slurries. The unique design of our inline sensors provides an unobstructed flow path and is available in a variety of materials for compatibility with most fluids. Our flow meters have been used to measure everything from liquefied gases to thick oils and pastes, corrosive chemicals, light hydrocarbons, water and water-based fluids.

Check out our complete list of applications.

Contact us about any flow measurement application you have.

How Are They Installed?
Rheotherm flow meters incorporate in-line flow sensors typically installed with standard tube fittings, but optionally available with flanges, sanitary fittings, etc. Any orientation is acceptable, except vertical with downward flow direction. With some models the electronics are integral to the sensor. Other models have a separate electronics enclosure that can be installed up to 200 feet from the sensor. Electronics Options

What Is the Turndown Ratio?
Typical calibration ranges are 10:1 (options up to 200:1), with good accuracy over the entire range. The sensors cannot be damaged by overranging.

How Do They Work?
Rheotherm sensor cutawayOur low flow meters use either a straight-through or looped flow tube with a heated and an unheated RTD attached to the outside of the tube. The temperature differential between the two RTDs provides the primary flow signal. At high flow rates the differential is lower as flow removes heat more readily. At low flow rates the differential is higher because less heat is removed. Nothing touches the fluid except the flow tube wall, and there are no mechanical parts to wear, stick or break. More on Method of Operation(PDF)

How Do I Get One?
Submit your Rheotherm inquiry today using the form on this page so we can review your application and prepare your quotation. You can also call or visit our Contact Us page for telephone, fax and email information.

  • No moving parts
  • Exclusive inline TU sensor
  • Advanced signal processing electronics
  • Field adjustable
  • Maintenance-free
  • Easy installation
  • Choice of wetted materials
  • Long-term reliability


  Standard Options
Temperature Process: 0 – 140°F
(-18 – 60°C)
Environment: 0 – 120°F
(-18 – 50°C)
-20 – 350°F
(-30 – 175°C)
Pressure 0 – 1,000 PSI Up to 30,000 PSI
Calibration Ranges – 10:1 Turndown
– 0.007 cc/min to 20 GPM
– Up to 200:1 turndown;
– Four calibration channels available (for multiple flow ranges or fluids using the same sensor)
Calibration Accuracy  ± 1% of reading typical
Response Time  1 sec. ; 3 – 5 sec. typ.
(63% of range)
Time constant/delay option
Repeatability ± 0.5% of reading
  Standard Options
Line Sizes
(flow range dependent)
1/16”; 1/8”; 3/16”; 1/4”;
3/8”; 1/2”: 5/8”; 3/4”; 1”
Other sizes via fittings/adapters
Process Connection Plain tube stubs suitable for compression fittings – MNPT:
– Tri-Clover (Sanitary);
– SS Flange (1/2″ – 2″);
Most other fittings available
Wetted Material 316 SS – Hastelloy C-276®;
– Monel®;
– Alloy 20;
– Titanium;
– Tantalum;
– Inconel
Display 2 X16 backlit LCD with selectable display of:
– Mass/volume flow rate
– temperature
– total accumulated flow
  Standard Options
Enclosure Sensor: PVC
Integrated Electronics:  NEMA 4X Cast Aluminum
Remote Electronics: NEMA 4
Sensor: Stainless steel
Remote electronics:
– Stainless steel
– NEMA 7 Explosion-proof
Hazardous Environment Integrated electronics
FM-Approved for:
– Class I, Div. 1, Groups B,C,D
– Class I, Zone 1, IIB+H2 (US)
– Class II, Div. 1, Groups E, F, G
– Class III, Div. 1
Remote electronics:
Same as above except addition of Group A using ISB
Outputs 4 – 20 mA (flow rate) or Serial Burst with Flow Rate, Totalizer, and Fluid Temperature – 0 – 10 or 0 – 5 VDC;
– Pulse (5 VDC open collector);
– HART (4-20 mA) ;
– SPDT relay;
– 4 to 20 mA temp
Input Power 24 VDC ±4V
(200 mA – blind unit; 300 mA w/display option)
110/230 VAC ±10V

Inline Sensor Flow Capacities for Liquids

FLOW RATE LIMITS C 1/16 1/8 3/16 1/4 3/8 1/2 5/8* 3/4* 1*
Extended Maximum 2 60 500 0.4 1 2.5 4.6 8 10 20
Normal Maximum 1 30 250 0.25 0.5 1 2 3.5 4.5 8
Normal Minimum 0.03 0.8 6 0.008 0.01 0.03 0.05 0.2 0.3 0.5
Extended Minimum 0.007 0.05 3 0.002 0.006 0.01 0.02 0.07 0.1 0.2
cc/min GPM

*Limited applications. Consult Factory

pdf (1) Product Brochure
word Rheotherm Flow Application Data Sheet (download document)
pdf (1) Rheotherm Method of Operation
pdf (1) Rheotherm Sensor Selection Guide
pdf (1) Rheotherm Model
Selection Guide
pdf (1) Standard Dimensions Inline (TU/TUL) Sensor
pdf (1) Rheotherm Model 210 Product Manual
Request a Quote

Required fields are indicated with an ‘*’Name*




City, State/Prov.



Density/Specific Gravity

Homogeneous? YN

Coats pipe?YN

Flow Range* (incl. units)

Fluid Temp.* (indicate °F/°C)

Max. Temperature*

Oper. Pressure (incl. units)

Max. Pressure* (incl. units)

Continuous or Batch Flow*
Batch/Pulse Time (secs)

Pipe/Duct Size*

Straightrun (# dia. up/down)

Preferred Wetted Material

Process Fittings

Flange Size/Rating

Local Display* YN
Input Power*

Flow Output* (ctrl-click for multiple)
Additional Requirements
(Hazardous environment, certificates, etc.)