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Brand: KELLER
KELLER Series 36XW Digital Level Probe RS485 Modbus
Description
KELLER Series 36XW is a piezoresistive submersible level probe with the highest accuracy in the KELLER standard probe range: 0.05 %FS for ranges from 0…0.3 to 0…30 bar. A 22 mm diameter, about 106 mm long AISI 316L body carries an RS485 Modbus RTU interface that can be combined with 4…20 mA or voltage output.
A digital hydrostatic probe for wells, tanks and rivers
The datasheet names hydrostatic pressure measurement, groundwater and surface-water level and fill-level measurement in water and fuel tanks. Besides pressure, the probe reports temperature from the sensor chip (accuracy 1.5 degC), with an optional Pt1000 sensor behind the transducer for 0.1 degC accuracy.
Total error band is 0.1 %FS over 0…50 degC. Long-term stability is typically 0.05 %FS per year with a 0.1 %FS maximum, and annual recalibration is recommended. Customised builds can integrate calculations such as tank content.
Key features as printed in the datasheet
- Digital RS485 (Modbus RTU, KELLER bus) with optional analog output.
- Accuracy 0.05 %FS; digital non-linearity 0.02 %FS; resolution 0.0005 %FS.
- IP68 cable gland; cable for water (PE or polyolefin) or fuels (TPE-E), 5 to 40 m.
- Standard surge protection; optional extended lightning protection.
- Medium temperature -20…85 degC; weight about 150 g without cable.
Technical specification
Performance and electrical data
| Parameter | Specification |
|---|---|
| Pressure ranges | 0…0.3 to 0…30 bar (PR relative, PAA absolute) |
| Accuracy at room temperature | max. 0.05 %FS |
| Total error band 0…50 degC | max. 0.1 %FS |
| Digital non-linearity | max. 0.02 %FS (BFSL) |
| Long-term stability | typ. 0.05 %FS, max. 0.1 %FS per year |
| Position dependency | max. 2 mbar |
| Temperature accuracy | 1.5 degC; optional 0.1 degC with Pt1000 |
| Outputs | RS485 with 4…20 mA, 0…10 V, 0…5 V or 0.1…2.5 V |
| Supply | 3.2…32 VDC (2-wire); 8…32 or 13…32 VDC (3-wire) |
| Start-up / internal rate | below 250 ms / 1800 Hz or more |
| Shock voltage protection | standard 50 A line-line, 200 A line-case (8/20 us); optional 10 kA line-line, 2 kA line-case |
Mechanical and environmental data
| Parameter | Specification |
|---|---|
| Housing and wetted parts | AISI 316L; end cap POM (316L optional); FKM seals |
| Oil filling | Silicone oil |
| Dimensions / weight | dia 22 mm x approx. 106 mm; approx. 150 g without cable |
| Pressure connection | None (end cap), optional G1/4 (ISO 228-1) |
| Cable sheath | Water: PE (PR) or polyolefin (PAA); fuel: TPE-E; standard lengths 5, 10, 15, 25, 40 m |
| Medium / ambient / storage temperature | -20…85 degC each; no icing |
| Ingress protection | IP68 cable gland |
| Vibration / shock | 10 g, 10…2000 Hz / 50 g, 6 ms |
Selection and ordering guide
Choose the range from maximum depth with the water-column table in the datasheet, and PR for vented installations or PAA where absolute pressure is wanted. Pick the cable sheath by liquid and the length by installation depth plus run to the terminal box. As a derived rule of thumb, one bar of hydrostatic pressure corresponds to roughly 10 m of water column, so a 0…3 bar probe suits wells and tanks of about 30 m depth or less; always read the water-column column of the range table.
Decide between 2-wire 4…20 mA with digital, or 3-wire voltage with digital. During communication the 4…20 mA signal is disturbed on 2-wire types, whereas 3-wire types can run both interfaces at once.
Installation and operation notes
Hang the probe on its own cable, keep the cable end in a dry terminal box (the PR version has a reference capillary inside), and protect the diaphragm behind the end cap, marked M in the drawing. KELLER recommends its K-114 RS485-USB converter and free CCS30 software to configure address, baud rate and scaling and to log up to 100 values per second.
Level probes on long outdoor cables see induced surges, so consider the extended lightning protection option for exposed sites.
Applications in Oman and the GCC
Boreholes and groundwater monitoring, water tanks, stormwater and wastewater sumps and fuel tanks are the datasheet use cases. Gulf utilities and contractors favour digital probes for remote telemetry because Modbus values reach a PLC or logger without analog drift over long cable runs.
Compatible accessories and related items
KELLER also lists Series 26X, 26Xi, 36XS, 36XiW and 36XiW-CTD probes. The analog Series 26Y is also listed on this site. Confirm range, cable sheath, cable length, the optional Pt1000 temperature sensor and surge-protection level in the datasheet before ordering.
Frequently asked questions
What does the 36XW measure?
Hydrostatic pressure from 0…0.3 to 0…30 bar, plus temperature, for level and depth measurement.
Which digital protocol does it use?
RS485 half-duplex with Modbus RTU and the KELLER bus protocol.
Can it be used in fuel tanks?
KELLER offers a TPE-E cable sheath for fuel applications.
What is the protection class?
IP68 at the cable gland.
Is Seven Star LLC a KELLER distributor?
No. Seven Star LLC is not a KELLER distributor; it is an independent Muscat-based supplier that quotes KELLER products on request.
Documents and quotation
This page carries the official KELLER datasheet for 36XW. Seven Star LLC is an independent supplier in Muscat and sources KELLER products on request; tell us the quantity and delivery point to receive a quotation. Always confirm the order code and technical values in the document first. See more in the product category.
Datasheets & Documents
- Datasheet KELLER Series 36XW datasheet, edition 05/2025 (PDF) Download
Reviews (0)
About brand
KELLER is a Swiss manufacturer of piezoresistive pressure sensors and transmitters, founded in 1974 in Winterthur by physicist Hannes W. Keller, who had co-invented the integrated silicon measuring cell in 1966. Its breakthrough came in 1977 with an order for 1,000 OEM measuring cells. KELLER is family-run, led by Tobias and Mike Keller since 2019.
KELLER company profile
| Founded | 1974, Winterthur, Switzerland, by Hannes W. Keller |
|---|---|
| Headquarters | Winterthur, Switzerland |
| Ownership | Keller family; led by Tobias and Mike Keller since 2019 |
| Technology | Piezoresistive silicon pressure measuring cells |
| Product families | Series 21, 23 and 33X pressure transmitters, OEM pressure sensors and measuring cells, LEO digital manometers, DCX and ADT level dataloggers, level probes, calibrators |
Milestones
- 1966: Hannes W. Keller co-invents the integrated silicon measuring cell.
- 1974: KELLER is founded in Winterthur.
- 1977: A 1,000-cell OEM order brings the breakthrough.
- 2024: KELLER marks 50 years.
Pressure transmitters and level probes
The KELLER range covers standard and front-flush pressure transmitters, differential and low-pressure transmitters, submersible level probes, digital pressure gauges and data loggers. Many X-line devices combine RS485 Modbus RTU with an analog output, and intrinsically safe or increased-safety versions are offered for hazardous areas.
Typical industries
KELLER lists oil and gas, water and environment, HVAC, chemistry, food and pharma, and raw material extraction among its industries. Seven Star LLC quotes KELLER transmitters and level probes in Oman and the GCC with the official datasheet for each item.
KELLER products we list
Facts checked against KELLER's own 50th anniversary release (keller-druck.com), October 2026.
Related products
Frequently Asked Questions
What does the 36XW measure?
Hydrostatic pressure from 0...0.3 to 0...30 bar, plus temperature, for level and depth measurement.
Which digital protocol does it use?
RS485 half-duplex with Modbus RTU and the KELLER bus protocol.
Can it be used in fuel tanks?
KELLER offers a TPE-E cable sheath for fuel applications.
What is the protection class?
IP68 at the cable gland.
Is Seven Star LLC a KELLER distributor?
No. Seven Star LLC is not a KELLER distributor; it is an independent Muscat-based supplier that quotes KELLER products on request.
Reviews
There are no reviews yet.