Model 591

SKU: 591

Pressure Transmitter, Cable Suspended, Integral Electronics

The Delta Controls Model 591 Pressure Transmitter incorporates both the sensor and the electronics unit in a single potted module. The module is protected by a Viton® sealed heavy stainless steel body. This lower body is sealed to an electrical cable, both of which are supported from the well head above. The sensor detects the pressure of the water surrounding it. This pressure is linearly proportional to the height of water above it. The sensor is connected to and referenced to atmospheric pressure by a vent tube in the cable. The sensor/electronics unit converts the pressureinto a 4-20 mA dc signal equivalent to the liquid level.

Unlike capacitance and admittance type devices, the 591 is unaffected by algae growth and sludge coating. It’s calibration can be ‘bucket’ checked or changed without the unit being installed in a well or it. It is inexpensive to purchase and install. It is also virtually maintenance free which results in a low cost of ownership

The 591 is extremely useful for measuring levels in tanks. The flexible cable is easy to install, even when the head room above a tank is minimal. The small body diameter allows it to be installed through a small 0.75 inch MPT hole. The optional Tefzel cable jacket and Hastelloy® C-276 body are resistant to most corrosive agents.


  • 4-20 mA dc signal, 2-wire loop
  • Small size is easy to install
  • Fits a 0.75 in NPT (23 mm) hole and slides easily into a 1.0 in (27 mm) pipe
  • Resistant to down hole pumps
  • Ranges 1 ft to 2500 ft (0.3 m to 762 m) in water
  • Support cable up to 2500 ft (762 m) long
  • Unaffected by algae and buildup
  • Spark and voltage surge protectors
  • Zero and Span pots for field recalibration
  • Cable and sensor can be replaced in the field
  • Cable support clamp provided
  • Sludge nose optional for dirty liquids
  • Second vent tube in cable to check down hole sealing
  • Maintenance free operation


  • Technology: Silicon strain gauge
  • Supply Power: 13 DCV to 35 DCV 2-wire loop powered
  • Output Signal : 4-20 mA dc, isolated
  • Loop Impedance: 550 Ω at 24 DCV, 1100 Ω at 35 DCV
  • Adjustments : 30% ≤ 100% of range
  • Basic Non-Interactive: Zero ≤ 30%
  • Vent Tube: Protected from moisture condensation by a desiccant filter or isolation bladder
  • Over Pressure: 22X range 35 psi (2.5 bar) min without damage 3X range 1000 psi (70 bar) min without rupture
  • Temperature Range:
  • Operating: -20 °F to +180 °F (-29 °C to 82 °C)
  • Intermittent: -40 °F to +220 °F ( -40 °C to 104 °C)
  • Compensated: +30 °F to +130 °F (-1 °C to +55 °C), higher available
  • Accuracy:± 0.25% FS or >
  • Thermal Error: ± 0.02% FS/°F max
  • Barometric Effect: None

Required Ordering Information

  • Detailed model number
  • Tag or nameplate detail (if required)
  • Factory calibration: custom range or full-scale
  • Documentation/testing tiers (if required, refer to Additional Resources in the product catalog)

Additional Information


Pressure Transmitter, Cable Suspended, Integral Electronics

Level Measurement


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