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 345 bar (5003 psi)
  • Temperature: -196°C (-321°F) up to +350°C (662°F)
  • Accuracy: 0.1 % of rate
  • Materials: SS 316L / SS 316Ti, Alloy C22 – 2.4602, Tantalum – UNS R05200, Super Duplex – 1.4410
  • Process Connection: ¾" up to 2 ½"
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

Contact us with specification for assessment and availability.

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