Mobrey 9710 Submersible Hydrostatic Level Transmitter 4-20 mA

Submersible hydrostatic level transmitter with ceramic capacitive sensor

The Mobrey 9710 is the cable suspended model of the 9700 Series analogue submersible hydrostatic level transmitters. It is a two-wire, 24 Vdc loop-powered transmitter with a 4-20 mA output, intended for tank level measurement where foaming, vapor layers or temperature gradients make other instruments difficult to use. A ceramic capacitive sensor with a flush diaphragm avoids clogging, and the datasheet states accuracy of +/- 0.1% of calibrated span, ranges up to 200 m (656 ft) of water, and 10:1 rangeability.

Technical specifications

Nominal ranges and overrange

Ordering code and installation

The code is built from the model (9710), version (C commercial or M marine approval), housing material (S stainless steel 316 or A aluminium bronze), body seal O-ring (1 fluorocarbon, 2 nitrile), nominal range, zero and span, cable material (P polyurethane or F FEP), cable length unit and length (3 to 200 m, or 9 to 600 ft), product certification (NA non-certified, A6 CSA hazardous area) and custom configuration C1. The instrument is a fixed range type, so the calibration within the measuring range must be stated at ordering. All cable includes a venting capillary; for humid environments or sea water applications, bellows must be used.

How the Mobrey 9710 works

The transmitter sits at the bottom of the tank or well, and the liquid above it presses on a ceramic capacitive sensor through a flush diaphragm. The pressure changes the capacitance, and the electronics turn this into a 4-20 mA signal on two wires. Because the pressure of a liquid column depends on its height, the signal shows the level. A vented cable carries the atmospheric reference to the sensor, so changes in air pressure do not affect the reading.

Where the 9710 is used

• Water and wastewater wet wells and sumps
• Deep boreholes and reservoirs
• Process tanks with foam or vapor layers
• Marine tanks and ballast measurement
• Fuel and chemical storage where the materials are suitable

Selection checklist for the 9710

• Range code from the table, from 1 m up to 100 m of water in the listed codes
• Housing: 316 stainless steel or aluminium bronze
• Seals: FPM/FKM or nitrile, to suit the liquid
• Cable type: polyurethane or FEP, and the cable length
• Hazardous area approval needed, such as Ex ia
• Marine approval if used on ships
• Loop supply of 10 to 30 Vdc and the loop resistance
• Liquid temperature, within -20 to +60 degrees C

Installation, commissioning and maintenance notes

Hang the transmitter on its own cable so that it is below the lowest level to be measured, and keep it clear of inlets that cause turbulence. Do not let the cable bend sharply, and keep the vent end of the cable dry in a suitable termination box. Check the loop supply against the load resistance formula. Adjust the span in the range given, then compare the output to a known level. Rinse the diaphragm gently if the liquid leaves deposits, and never poke it with a hard tool.

Requesting a quotation for the Mobrey 9710

Please send the range code, the cable length and type, the housing material, the seals and any approvals. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

9710 accuracy and stability

The accuracy is 0.1 percent of the calibrated span, including linearity, hysteresis and repeatability. Stability is 0.1 percent of the upper range limit over six months.

9710 response and temperature effect

The response is about 60 ms to reach 63 percent of a pressure change, and 150 ms to reach 90 percent. The temperature effect is 0.015 percent of the upper range limit per degree.

9710 ingress protection

The submersible housing is rated IP68 and NEMA 6P to a depth of 200 m of water.

9710 weight and cable

The sensor weighs 0.7 kg. The cable weighs 71 kg per km in air, which matters for long hangs.

Level transmitter records for 9710

Keep the range code, the cable length, the installed depth and the calibration data with the tank file.

Documents and quotation

Check that the housing, seal and cable materials suit the liquid, because the datasheet leaves compatibility with the purchaser. Confirm depth range, cable length, whether a hazardous-area or marine version is needed, and the termination arrangement. The 9700 Series also includes externally mounted floodable versions covered elsewhere in the manufacturer literature.

The manufacturer document is attached to this page and listed below. Seven Star LLC is an independent supplier in Muscat and can quote against the model code, quantity and delivery location. Browse more instruments in Level Instrumentation, or see the Mobrey brand page.