The INVALCO water cut system combines the Model CX-645 capacitance probe, the Model 4528 detector and (optionally) the Model 4728 monitor to measure percent water in a flowing crude oil emulsion stream. The 4528 detector gives a direct 0-5 VDC or 4-20 mA output on its own; the 4728 monitor adds a four-digit LCD, a 4-20 mA retransmission and a time-delayed limit relay for diverter valve control or alarms. Typical uses are LACT units, pipeline loading, dehydration equipment, fuel oil monitoring and storage/treating facilities. NACE-adaptable.
Key specifications
- Ranges: 0-5%, 0-10% or 0-20% water (4528EZ detector field-selectable)
- 4528 detector accuracy: +/-1.0% of full scale; resolution +/-0.5% of full scale
- 4528 power: 12 VDC @ 130 mA for 0-5 VDC output; 24 VDC required for 4-20 mA output
- 4728 monitor power: 18-28 VDC @ 130 mA, or 115/220 VAC
- 4728 outputs: 4-20 mA (2-wire internally powered or 3-wire externally powered); SPDT relay 10 A @ 250 VAC
- 4728 relay time delay: 0-90 s adjustable in 10 s steps; off-delay about 10% of on-delay
- 4728 enclosures: NEMA 4X weatherproof, NEMA 7 explosion-proof Class I Div 1 Groups C & D, or panel mount
- CX-645 probe: Concentric-tube probe, A53 Gr B carbon steel standard (stainless available), baked-on phenolic epoxy wetted surfaces, PTFE spacers
- Probe sizes: 2" I.D. x 17" face-to-face; 3"-10" I.D. x 32" face-to-face (12" and up to 16" consult factory)
- Probe connections / pressure: ANSI RF or RTJ flanges to 600# (all sizes), MNPT or grooved on 2"-3"; 1,440 psig max. (Victaulic grooved 350 psig)
- Probe temperature: 0-165 °F standard; -20 to 375 °F optional
- Approvals (probe/detector): UL/C-UL explosion-proof, Class I Div 1 Groups C & D; Class II Groups E, F, G
How to read the model code
Example: CX-645-360-BFP. Read the code left to right; each position selects one option:
- Base: CX-645 water cut probe (0-20% water), for use with a Model 4528 detector
- Probe body size: 2 = 2" I.D. x 17" F-F; 3, 4, 6, 8 = 3"-8" I.D. x 32" F-F
- End connection: 00 = screwed (to 3") / grooved Victaulic (to 4") / 150# RF; 30 = 300# RF; 60 = 600# RF (Sch 80); 90 = 900# RF (Sch 80); 05 = 150# RTJ; 35 = 300# RTJ; 65 = 600# RTJ (Sch 80); 95 = 900# RTJ (Sch 80); 115 = 1500# RTJ (Sch 160)
- Material / temperature: B = standard A105 carbon steel, 0-200 °F; H = standard / high temp, 0-375 °F; S = 316 SS; T = 316 SS / high temp, 0-375 °F
- Connection style: S, G or F (the bulletin lists these letters with no descriptions)
- Coating: P = phenolic coating (interior)
Model 4728 monitors (part numbers): 4728-PM panel mount, all ranges 81001148; 4728-5WP 81001114; 4728-5XP 81001115; 4728-10WP 81001126; 4728-10XP 81001116; 4728-20WP 81001128; 4728-20XP 81001117 (WP = NEMA 4X, XP = NEMA 7). Model 4528 detectors: 4528-5 (0-5%, 0-5 VDC) 81001164; 4528-5A (4-20 mA) 81001295; 4528-10 81001160; 4528-10A 81001294; 4528-20 81001161; 4528-20A 81001162; 4528EZ field-selectable P518796; 4528 test kit 81000520. The 4528 detector must be ordered separately from the CX-645 probe. Bulletin errors to confirm with the factory: code 00 is printed for screwed, grooved and 150# RF ends; the 600# RF and RTJ codes are marked "for 8" and 10"" yet the example (CX-645-360-BFP) is a 3" probe with code 60; the size group stops at 8" although the dimension table lists 10"; the connection-style letters S/G/F have no descriptions; the last group is headed "Open"; and the 4728 temperature range is printed 0-160 °F = -20 to 70 °C (0 °F is about -18 °C).
Pricing and lead time are quoted per configuration. Send the model code (or your application details), product, flow range, and pressure/temperature to Flow Measurement Services for a quote. Specifications summarized from Smith Meter (INVALCO) bulletin SSIN015 Rev 0.1 (11/18); confirm current data with the factory before ordering.
Smith Meter (formerly FMC Technologies / TechnipFMC Measurement Solutions), now manufactured by Guidant. Flow Measurement Services supplies and services Smith Meter equipment.

