Model 4528, 4528EZ and 4728 Monitors CX-645 Probe-Water Cut Monitors

The INVALCO Model 4728 Water Cut Monitor, in conjunction with a Model 4528 Detector and a Model CX-645 Capacitance Probe is a continuous on-line monitor or percent water in a flowing crude oil emulsion stream. This unit displays percent of water in various ranges from 0-5% up to and including 0-20% on a digital LCD indicator. In addition, the Model 4728 provides a 4-20 mA analog output proportional to input range, and a field-adjusted, time-delayed, limit relay for valve control or alarming.



  • Real-time display and retransmission of water cut monitor: Allows quick response to upset conditions for downstream controls.
  • Adjustable delay of relay closure: Prevents nuisance alarms and “actuator overload”.
  • Direct analog output from model 4528 detector: A 4-20 mA signal is available from the probe without the need to include the Model 4728 monitor.
  • NACE adaptable: Can be modified for use in NACE applications.


LACT (Lease Automatic Custody Transfer) Units
Detect and provide relay contact closure that can be used to reroute oil that has excess water cut.
Pipeline Loading
Monitor transfer of petroleum/condensate products from loading facilities.
Dehydration Equipment
Determine and enhance equipment efficiencies, by monitoring the product and indicating water content.
Fuel Oil Monitoring
Determine contamination of fuel oil by condensation, or other external factors, before entry to engine.
Storage and Treating Facilities
Monitoring and early detection of undesirable conditions as well as interface detection during dewatering of storage tanks.


Model 4728 Specifications
Power Supply 18-28 Vdc @ 130 mA
115/220 Vac
Water Cut Monitor Full Scale Range 0-5%, 0-10%, and 0-20% range options.
Display Four digit LCD with decimal point.
Analog Outputs 4-20 mA, 2-wire internally powered or 4-20 mA,
3-wire externally powered.
Relay Output SPDT Relay, 10A, 250 Vac.
1/2 Hp 250 Vac, 10A – 120 Vac resistive.
1/3 Hp 120 Vac, 10A – 30 Vdc resistive.
Time Delay 0 to 90 seconds adjustable in 10 second increments.
Off-delay approximately 10% of on-delay time.
Temperature Range 0°F to 160°F (-20°C to 70°C).
Enclosures NEMA 4X, weatherproof.
NEMA 7, explosion-proof, Class I, Division 1, Groups C
and D.
Model 4528 Detector / Probe Specifications
Power Supply 12 Vdc @ 130 mA for 0-5 Vdc output.
24 Vdc required for 4-20 mA output.
Water Cut Monitor Range 0-5%, 0-10%, and 0-20%
Measurement Accuracy ±1.0% of full scale
Resolution/Sensitivity ±0.5% of full scale
Probe MaterialA53 GrB Carbon Steel is standard. (Stainless Steel available.)
Probe FinishBaked-on phenolic two-part epoxy
Probe Sizes/Length 2″ I.D. is 17″ face-to-face.
3″ to 12″ I.D. sizes are 32″ face-to-face
Process Connections ANSI RF or RTJ Flanges to 600# (all sizes)
(others by special order).
Threaded MNPT or Grooved (2″ and 3″).
Pressure Ratings As per Flange selection, 1440 psig max.
NPT – 1440 psig max. (Victualic grooved – 350 psig)
Temperature Range0°F to 165°F standard. (-20°F to 375°F optional.)
Approvals UL/C-UL Explosion-proof certificate for Class I,
Div. 1, Groups C and D or Class II, Groups E, F,
and G hazardous locations.


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