RHM 02

FLOW SENSOR

The RHM 02 is available with a wide selection of wetted materials and the highest pressure and temperature ratings in the market. It is suitable for all low flow applications where high accuracy is a must.

Range: 0.01 kg/min up to 2.7 kg/min
Pressure: up to 1436 bar (20827 psi)
Temperature: -196°C (-321°F) up to +350°C (662°F)
Accuracy: 0.1 % of rate
Materials: SS 316L / SS 316Ti, Super Duplex – 1.4410, Alloy C22 – 2.4602
Process Connection: ¼" up to 1"

CONFIGURE

CATEGORY Small Size Sensors, Chemical Injection, Oil Measurement, Painting/Coating Lines

Performance Data

Flow Measurement Uncertainty
Standard: 0.20 % of rate
Enhanced: 0.15 % of rate
Premium: 0.10 % of rate
Ultimate: 0.05 % of rate – requires RHE 40 Series transmitter
Low Flow Calibration: 0.10 % of rate – requires RHE 40 Series transmitter
Customized Calibration: Consult factory

Low flow calibration focuses on the range from ½ × Qₙₒₘ downwards to lower flow rates than on other calibrations. Often used for low pressure gas or very viscous liquids. Customized calibration uses specific calibration points according to customer requirements.

Flow Measurement Repeatability
Standard Sensors: ±0.1 % of rate
Premium Sensors: ±0.05 % of rate

Temperature Measurement
Better than ±1 °C

Density Calibration (Liquid)
Standard: ±0.001 kg/l uncertainty
Premium: ±0.0005 kg/l uncertainty – requires High Accuracy or Focused Calibration Option

Reference conditions: 18–24 °C Water @ 1–3 bar

Measurement Tube Pressure Ratings

The maximum pressure (pₘₐₓ) of a sensor is determined by its lowest rated part: the measurement tube (see table below), the connection block (see datasheet) or the process connection (see corresponding standards or manufacturer information).

If applicable, the material of a connection block is always SS 316L. For sensors in sealless versions, the material of the process connection is usually the same as the material of the measurement tubes. In special cases, the material may differ.

	50 °C 122 °F	120 °C 248 °F	210 °C 410 °F	350 °C 662 °F
SS 316L (standard)	314 bar 4554 psi	279 bar 4047 psi	236 bar 3423 psi	199 bar 2886 psi
Alloy C22	455 bar 6599 psi	404 bar 5859 psi	343 bar 4974 psi	285 bar 4133 psi
Super Duplex * Low Pressure	728 bar 10559 psi	677 bar 9819 psi	608 bar 8818 psi
Super Duplex * Medium Pressure	950 bar 13779 psi	900 bar 13053 psi	840 bar 12183 psi
Super Duplex * High Pressure	1436 bar 20827 psi	1337 bar 19392 psi	1199 bar 17390 psi

* Minimum operating temperature for Super Duplex stainless steel is -40 °C. Maximum pressure may be lower depending on the design type.

Uncertainties and flow measurement turn-down

The turn down capability from Qₙₒₘ of the flow sensor is driven mainly by its zero point stability. At the very low end of the measuring range the uncertainty (u) is dominated by zero point stability.

• Zero point stability of a standard sensor with general accuracy calibration: 0.00009 kg/min (0.000198 lbs/min).
• Zero point stability of a premium sensor with high accuracy or focused calibration: 0.00003 kg/min (0.000066 lbs/min).
• uncertainty = calibration uncertainty, if: flow ≥ (zero point stability / (base uncertainty/100))
• uncertainty = (zero point stability/Q)*100, if: flow < (zero point stability / (base uncertainty/100))

Uncertainties from environmental and process conditions

If sensors are not zeroed at operating conditions, minor additional uncertainties can arise from elevated temperatures and pressures:

• ±0.002111% of maximum flow per °C
• ±0.00963% of maximum flow per bar

Process temperature effect on density:
• Additional uncertainty of ±0.000156 g/cm³ per °C difference from calibration temperature with standard density calibration.
• Additional uncertainty of ±0.000036 g/cm³ per °C difference from calibration temperature with enhanced density calibration.
• This effect can be mitigated by a simple field density adjustment at operating conditions.

Process pressure effect on mass flow:
• The effect of pressure on flow measurement is 0.001% of rate per bar. Compensation is possible by pressure sensor input (analog input or digital write) or manual value entry into the transmitter.

Process pressure effect on density:
• The effect of pressure on density measurement is 0.00002 g/cm³ per bar. Compensation is possible by pressure sensor input (analog input or digital write) or manual value entry into the transmitter.

Applying Premium calibration to higher pressure, special materials and/or non-standard temperature models may show higher zero uncertainties (up to 3 times higher than standard sensor).

Couldn’t find what you were looking for?

Other wetted materials may be possible for chemical compatibility, lower pressure drop, abrasion allowance or other application specific requirements. Rheonik can provide nearly any material for the wetted parts.