JUMO MAERA S28 Stainless Steel Hydrostatic Level Probe, 404392

A stainless steel submersible probe for wells, sumps and wastewater tanks

The JUMO MAERA S28 (type 404392) is a level probe for continuous hydrostatic level measurement of liquids. It is lowered into the liquid, and the weight of the liquid column above the probe presses on a piezoresistive silicon cell, which outputs a 4 to 20 mA signal proportional to the filling height. Ranges cover 0.25 to 10 bar, which is 2.5 to 100 metres of water column in ventilated tanks. A special cable with a built-in pressure equalisation hose takes the ambient air pressure to the back of the cell, so barometric changes are compensated automatically. The datasheet lists water and sewage management, hydroelectric power stations, and wells and surface water as applications, and the probe is approved for use in drinking water, with indoor and outdoor installation allowed.

Technical specifications

Probe versions and ranges

The standard type 000 is vented through the hose in its cable, while the deep well type 025 uses a two-core EPR cable without a compensation hose, and the order list gives the 4, 6 and 10 bar ranges as sealed gauge. The datasheet notes that the stainless steel version with a mounted cage protects the membrane in difficult measurements with sludge, turbulence or currents, for example in pumping stations and wastewater lifting stations, and the extra weight steadies the output in strongly moving media. Choose the range from the maximum depth: for example the 0 to 1 bar range gives about 10 m of water, with an overload capability of 3 bar and a burst pressure of 4 bar.

The datasheet quotes long-term stability of 0.2 % of span per year or better and an overload capability of three times the range, so a probe in a deep, fluctuating tank tolerates surges from pumps. Reference conditions follow DIN 16086 and EN 60770, and the device survives more than 10 million load changes between 0 and 100 % of the range. The outer cable sheath is PE, PUR or FEP, all with stated UV resistance, which helps outdoor installations in strong sun.

Installation notes

Hang the probe vertically from its cable. If the cable or the hose is kinked or pinched, ambient pressure compensation is blocked and the signal will drift, so respect the bending radius of 120 mm fixed and 160 mm moving on type 000. The cable tensile force is up to 400 N. Keep the cable end in the dry terminal box with pressure compensation, ground the device and all connected pumps and valves to the same potential, and wire the two-wire loop to DC 24 V. For water with a different density, a Pt100 in the probe allows temperature-based correction. Check that the wetted materials suit the liquid, because 316 Ti and FPM or EPDM are not suitable for every chemical.

See the level instrumentation category for related level products.

Using the MAERA S28 in Oman and the GCC

Submersible level probes are widely used in the region in water wells, borehole monitoring, reservoirs, sewage pumping stations, treated effluent tanks and storm water sumps. They are simple to install, as the probe is lowered on its cable, and they give a continuous 4 to 20 mA signal for pump control and level monitoring.

Choose the range to suit the maximum water depth, and use a stilling tube in turbulent tanks or near pump inlets. The vent hose in the cable must stay open and dry, so terminate it in a junction box with a filter element, especially in humid coastal areas. In sewage applications, the probe should be cleaned at regular intervals to remove deposits from the diaphragm. Protect the cable from sharp edges and fix it so that the probe hangs freely.

Send the tank or well depth so the range and cable length can be matched correctly.

Information to send with an enquiry

• Measuring range and liquid
• Cable length
• Approvals needed, such as drinking water or Ex
• Accessories: suspension clamp, junction box or stilling tube

Related JUMO products: JUMO MAERA S25 Hydrostatic Level Probe, JUMO MAERA S26 Hydrostatic Level Probe for Tanks and Wells, JUMO MAERA S29 SW Titanium Level Probe, JUMO MAERA F27 Ceramic Level Probe with PTFE or Steel Case, JUMO NESOS R20 LT Float Level Transmitter and JUMO NESOS R04 LS Bent Float Level Switch.

Documents and quotation

The hosted document is JUMO data sheet 404392 (10 pages, English). It includes dimensions, wiring and order details. Confirm range, cable material and length, version and extras before ordering. Seven Star LLC is an independent supplier in Muscat; send the depth, liquid and cable length for a quotation. To help us prepare an accurate quotation, please include the medium, tank height, operating pressure and temperature, required output signal and hazardous-area requirements, together with the quantity needed and the delivery location. We will then compare these details with the order information in the datasheet.