Reference

RHM 20

FLOW SENSOR

The RHM 20 is a 2″ meter designed for general purpose flow measurement without the need for maintenance. Robust and accurate, the RHM 20 outperforms other flow technologies at an attractively low cost of ownership.

Range: 1 kg/min up to 480 kg/min
Pressure: up to 400 bar (5801 psi)
Temperature: -50°C (-58°F) up to +210°C (410°F)
Accuracy: 0.1 % of rate
Materials: SS 316L / SS 316Ti, Alloy C22 – 2.4602, Tantalum – UNS R05200, Super Duplex – 1.4410
Process Connection: 1" up to "

CONFIGURE

CATEGORY Medium Size Sensors, Chemical Injection, Fuel Consumption, Oil Measurement, Plastics Production

Performance Data

Flow Measurement Uncertainty
Selected Sensors down to ±0.10 % ¹ of rate (Gold Line)
Standard Sensors down to ±0.15 % ² of rate

Flow Measurement Repeatability
Down to ±0.05 % of rate

Temperature Measurement
Better than ±1 °C

Density Calibration (Liquid)
Selected Sensors down to ±0.0005 kg/liter (Gold Line)
Standard Sensors down to ±0.001 kg/liter

Measurement Tube Pressure Ratings

The maximum pressure (pmax) of a sensor is determined by its lowest rated part. The lowest rated part can be either the measurement tube (pmax indicated below), the connection block/manifold
(pmax indicated in the mechanical construction section) or the process connection (for pmax see published standards or manufacturer information).

	50 °C 122 °F	120 °C 248 °F	210 °C 410 °F
SS 316Ti (standard) Low pressure	208 bar 3017 psi	185 bar 2683 psi	156 bar 2263 psi
Alloy C22	193 bar 2799 psi	171 bar 2480 psi	146 bar 2118 psi
Tantalum	44 bar 638 psi	39 bar 565 psi	36 bar 522 psi
Super Duplex Low pressure ³	586 bar 8499 psi	514 bar 7455 psi	464 bar 6730 psi
SS 316Ti (standard) Medium pressure	250 bar 3626 psi	225 bar 3263 psi	193 bar 2799 psi
Alloy C22	260 bar 3771 psi	232 bar 3365 psi	196 bar 2843 psi
Super Duplex Medium pressure ³	481 bar 6976 psi	448 bar 6498 psi	402 bar 5831 psi
SS 316Ti (standard) High pressure	392 bar 5685 psi	345 bar 5004 psi	300 bar 4351 psi

Uncertainties and flow measurement turn-down

All uncertainty statements refer to reference conditions – mass flow of water, 18 – 24 °C, 1 – 3 bar in a standard temperature, pressure and material configuration sensor. The sensor can be used to measure gas – uncertainty values for gas equal the liquid value plus 0.3 %. Reference conditions for gas are mass flow of natural gas, 18 – 24 °C, 35 to 100 bar in a standard temperature, pressure and material configuration sensor.

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. The zero point stability of a standard sensor is: 0.00246 kg/min (0.00542 lbs/min). Zero point stability of a Gold Line sensor is 0.0012 kg/min (0.00264 lbs/min).

For flow Q ≥ zero stability / (calibration uncertainty/100) u = calibration uncertainty
For flow Q < zero stability / (calibration uncertainty/100) u = (zero stability/Q) x 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: ± 0.00022 % of maximum flow per °C and ±0.0005% of maximum flow per bar.
Process temperature effect on density: additional uncertainty of ±0.000071 g/cm³ per °C difference from calibration temperature with standard density calibration and of ±0.000009 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 0.0001 % 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 0.000075 g/cm³ per bar. Compensation is possible by pressure sensor input (analog input or digital write) or manual value entry into the transmitter.

(1) Requires 40 Series transmitter or higher
(2) Requires RHE16 or higher transmitter.
(3) Note minimum operating temperature for SuperDuplex stainless steel is -40°C

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.