Rheotherm flow switches provide reliable switch protection in all types of liquid or gas service. From critical monitoring of extremely low flow process additives to loss of flow protection in large water or air lines, we can handle most flow switch applications. With no moving parts, long term reliability is assured. Options for hazardous locations (intrinsically safe/explosion-proof) are available.
What Kind of Service?
You name it – all types of liquids and gases, big pipes or small lines, hot or cold. The application section has a complete list of fluids. Contact Us about any application you have.
How Are They Installed?
Our in-line flow switches for monitoring flows in small lines are typically installed with standard tube fittings, but are optionally available with flanges, NPT, sanitary fittings, etc. Insertion probe flow switches for monitoring large (1” or larger) pipe flows are typically installed with 1” NPT or flange fittings. Can be used in vertical or horizontal lines. For most common applications, the sensor and electronics are an integral unit.
How Do They Work?
Our in-line sensors use a straight-through flow tube with a heated and an unheated RTD attached to the outside of the tube. The insertion probe flow sensors have one tip with a heated RTD and a second tip with an unheated RTD. With either sensor style, the temperature differential between the two RTDs provides the primary flow signal. At high flow rates, flow removes more heat resulting in a lower differential. At low flow rates, flow removes less heat so the differential is higher. Nothing touches the fluid but the metal sensor wall, and there are no mechanical parts to wear, stick or break. Trip points are field adjustable. More on Method of Operation (PDF)
What Models are available?
Model 100CS – Lowest cost industrial option. Integral sensor/electronics with one SPDT relay. Can be ordered with in-line or insertion probe sensor.
Model 100FS – Separate sensor and electronics with one SPDT relay. Option for second relay for high and low set points. Can be ordered with in-line or insertion probe sensor.
Model 400 – Integral insertion probe sensor and electronics; has nonlinear output signal option.
Model 500 – Flow switch for certain general purpose applications; 24 VDC input power only.
How Do I Get One?
Submit your flow switch inquiry today using the form on this page, 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 switch point
- Easy installation
- Choice of wetted materials
- Long-term reliability
|Temperature||Process: 0 – 140°F
(-18 – 60°C)
Environment: 0 – 120°F
(-18 – 50°C)
|Inline: -20 – 350°F
(-30 – 175°C)
Probe: -20 – 400 °F
(-30 – 200 °C)
|Pressure||0 – 1,000 PSI||Up to 30,000 PSI|
|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|
|Line Sizes||Inline sensor (flow range dependent):
– 1/16”; 1/8”; 3/16”; 1/4”
– 3/8”; 1/2”; 5/8”; 3/4”; 1”
Pipe/Duct from 1.5” – 72”
(round, square, rectangular)
|Other sizes via fittings/adapters|
|Process Connection||Inline sensor: Plain tube stubs suitable for compression fittings
Probe sensor: 1″ MNPT
– Tri-Clover (Sanitary);
– SS Flange (1/2” – 2”);
Most other fittings available
|Wetted Material||316 SS||– Hastelloy C-276®;
– Alloy 20;
– Inline – PVC
– Probe – NEMA 4X (junction box)
– Integrated – NEMA 4X Cast Aluminum
– Remote – NEMA 4
|Inline sensor: Stainless steel
– Stainless steel
– NEMA 7 Explosion-proof
|Hazardous Environment||Remote electronics with 100FS only
FM Approved for:
– Class I, Div. 1, Groups A,B,C,D
– Class I, Zone 1, IIB+H2 (US)
– Class II, Div. 1, Groups E, F, G
– Class III, Div. 1
|Outputs||Single SPDT Form C relay
(10A, 125 VAC)
|Remote electronics with 100FS only
– Second independent SPDT relay
– DPDT relay
– Time delay on switch
|Input Power||110/230 VAC ±10V||24 VDC ±4V (200 mA)|
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*|
*Limited applications. Consult Factory
Inline Sensor Flow Capacities for Gases
|FLOW RATE LIMITS||C||1/16||1/8||3/16||1/4||3/8||1/2||5/8||3/4||1|
Probe-type Sensor Flow Capacities for Gases
|VELOCITY LIMITS (ft/min)||Liquid*||Gas|
*Liquid Applications limited to Flow Switches only