Aquameta™ CR420-0.5NPU

Hydrostatic water level sensor

  • Description
  • Technical specifications
  • Downloads

The CR420 series of 4-20mA pressure transducers are a cost effective and robust solution designed for continuous water level measurement where a 4-20mA output is required. It may be used with other liquids that are compatible with its wetting materials which are UPVC, Nitrile and Aluminum Oxide. Different choice of seals is available for other applications. The CR420-0.5NPU is suitable for pressure application of 0.5 bar (5.1m H2O). A 1 bar option is available. The sensor includes temperature and barometric pressure compensation.

Transducer Construction
This state of the art pressure sensor uses a flush Aluminum Oxide Ceramic diaphragm in conjunction with on-board signal conditioning to measure pressures. Pressure and temperature calibration is done electronically with the internal application-specific integrated circuit (ASIC). When pressures and temperatures change, the electronics provide an offset and span correction. It also includes aging detection and compensation. This new method guarantees good precision and long term stability. The sensor is encapsulated in a UPVC body that is filled with an epoxy. The sensor cable is molded into the transducer eliminating problems associated with threaded plugs. This design ensures a very high level of reliability.


  • 4-20mA output
  • 9 to 30V
  • Temperature compensated
  • Barometric pressure compensation via vented cable
  • High linearity and low hysteresis values
  • EMI Certified
  • Excellent resistance to corrosion and abrasion
  • Automated offset and span correction
  • Age compensation

Output Signals
The CR420 transducer uses a two wire 4-20mA output signal. The signal is linear with pressure. The sensor will operate with a supply voltage that can range from 9V to 30V DC. The Aquameta Junction box may be used to extend the transducer cable with any other cable. The vented junction box has a Gortex covered opening that allows venting to atmosphere to take place whilst restricting the ingress of moisture.


  • Level measurement in above and underground tanks
  • C-Bus home automation systems for water tank level display
  • Building management (BMS) for monitoring rain-harvesting and fire fighting tanks

Input pressure range
Nominal pressure gauge [bar]    0.5    1
Level [mH2O]    5    10
Overpressure [bar]    1    2
Burst pressure ≤ [bar]    2    4

Output signal / Supply
Standard 2-wire: 4… 20 mA/Vs = 9 … 35Vdc

Accuracy    ≤ ± 0.5% FSO
Permissible load    Rmax = [(Vs – 9)/0.02A]Ω
Influence effects    Supply: 0.05 % FSO/10V    Load: 0.05 % FSO /kΩ
Long term stability [%FS/year]    ≤ ± 0.3 @ 25 [°C]
Response time    ≤ 5ms

Thermal Effects(Offset and Span)
Thermal error     ≤ 0.007mA/10[°C]

Permissible temperatures
Medium: -25/+65[°C]    Storage: -40/+135[°C]

Electrical protection
Short-circuit protection    Permanent
Reverse polarity protection    No damage – no function
Norms compliance    Radiated electromagnetic field IEC/EN 61000-4-3(2006)    Electrical fast transition burst IEC/EN 61000-4-4(2004)    RF conducted disturbances IEC/EN 61000-4-6(2006)
RoHS compliance    RoHS

Electrical connection
Cable with sheath material     PVC (0 … 65°C) black
Standard cable length     10m (Custom cable lengths available)

Materials (media wetted)
Housing     U-PCV grey
Seals     Nitrile
Diaphragm     Ceramic AL2O3 96%

Current consumption     Min 3.8mA Max 20.4mA
Weight     ± 135g (without cable)
Ingress protection     IP 68
Country of origin     Australia
Warranty      1 Year

The following downloads are available for the Aquameta™ CR420-0.5NPU
Download Aquameta™ CR420-0.5NPU PDF