LMK809 Plastic Submersible Low Level Transmitter

IP68 low range pressure transmitter for measuring the level of highly contaminated and aggressive liquid media with a body made from PP-HT (Polypropylene HT) or PVDF. Hydrostatic level ranges from 0.4 up to 100 metres of water column.

The LMK 809 chemical resistant immersible level sensor includes a ceramic pressure sensing diaphragm which is highly corrosion resistant to most chemicals.

For waste-water applications the ceramic sensing element of the LMK-809 submersible level transmitter is semi-flush to prevent clogging and facilitate easy cleaning.

Contents

Product Parameters

Hydrostatic Level Ranges: 0.4 to 100 metres of water gauge
Accuracy: 0.35% FS or 0.25% FS (IEC 60770)
Output Signal: 4-20mA 2wire
Electrical Connection: PUR, FEP or TPE-U cable with IP68 watertight seal
Pressure Connection: Open face flush diaphragm with removable nose cone
Media Compatibility: PP-HT or PVDF sensor housing, FKM, EPDM or FFKM O ring seals and Ceramic Alumina Al2O3 (99.9%) diaphragm
Operating Temperature Range: 0…60 °C for PP-HT housing and -30…60 °C for PVDF housing
Dimensions: 45 mm diameter
Weight: 320 g
Special Features: Compatible with aggressive media, no metal parts exposed to the media
Special Options: vented sensor termination enclosure with PT100 transmitter and/or over voltage protection circuit, R1 thread pipe mounting

Product Description

The LMK809 plastic submersible low-level transmitter provides robust, precise continuous liquid level measurement in demanding industrial environments. Designed specifically for media that are highly aggressive, contaminated, or viscous, the transmitter utilizes a non-corrosive plastic probe body with an outer diameter of 45 mm. Process engineers can select standard PP-HT housing for operating environments between 0…60 °C or PVDF housing for broader chemical resistance and temperature demands ranging from -30…60 °C. The flush-mounted capacitive ceramic sensing element made from 99.9% Al2O3 delivers exceptional mechanical strength and chemical inertness, resisting corrosion from most acids, lyes, and industrial effluents. For applications requiring extra diaphragm protection against specialized chemicals, an optional PTFE foil coating is available.

The transmitter features high overpressure resistance, up to 35 bar on higher ranges, protecting the internal electronics against hydraulic pressure peaks and water hammer. Measurement accuracy conforms to IEC 61298-2 with a standard rating of ≤ ±0.35 % FSO and an optional higher accuracy of ≤ ±0.25 % FSO. Internal signal conditioning electronics convert the measured hydrostatic pressure into a standard 2-wire 4…20 mA analog output. Power is supplied via a 9…32 VDC loop, and the system incorporates permanent short-circuit protection, reverse polarity protection, and electromagnetic compatibility compliant with EN 61326 standards.

To ensure optimal material compatibility across diverse fluids, the LMK809 offers customizable media-exposed elastomeric seals, including FKM, EPDM, and FFKM. Electrical interconnection is made via a shielded multicore cable equipped with an integrated air capillary tube for atmospheric pressure equalization. Cable sheathing options include PUR (-25…70 °C), FEP (-25…70 °C), and TPE-U (-25…100 °C). The transmitter is rated IP 68 and can be configured with an optional plastic pipe mounting setup or stainless steel terminal clamps for reliable, secure tank suspension.

Product Applications

Wastewater and Sewage Systems

The LMK809 is ideally suited for continuous hydrostatic level tracking within demanding wastewater infrastructure. It performs reliably in sewage treatment plants, providing precise data even in sludge holding basins where solids accumulation is common. Its robust construction ensures it remains operational in effluent sumps, effectively monitoring flow and volume despite the presence of contaminants, harsh biological agents, and variable sewage characteristics.

Hydrofluoric acid (HF) 50% solution

Measure the level of 50% concentration hydrofluoric acid solution in small storage tanks using a LMK809 with a PTFE coated Ceramic diaphragm, PVDF housing, FFKM seals & FEP cable configuration.

SKU ID: s1-lmk809-0009
Part No: 395-1600-B-C3-1-7-8-3-005-000
Pressure Range: 0 to 0.16 bar
Reference Type: Gauge / Vented (atm to +P)
Output Signal: 4-20mA, 2 wire
Accuracy: 1% FS
Installation Type: Submersible probe with flush diaphragm
Housing Material: PVDF
Diaphragm Material: Ceramic Al2O3 99.9% with PTFE foil
Media Exposed Seals: FFKM
Cable Type: FEP (70degC max)
Cable Length: 5
Cable Length Units: Metres (m)
Optional Extras: PTFE coated diaphragm (1% acc., 160 mbar and above, ambient temp., no vac.)

Hydrochloric acid (HCL) 37% solution

Measure the level of 37% concentration hydrochloric acid solution in small storage tanks using a LMK809 with a PTFE coated Ceramic diaphragm, PVDF housing, FKM seals & FEP cable configuration.

SKU ID: s1-lmk809-0010
Part No: 395-2500-B-C3-1-1-8-3-005-000
Pressure Range: 0 to 0.25 bar
Reference Type: Gauge / Vented (atm to +P)
Output Signal: 4-20mA, 2 wire
Accuracy: 1% FS
Installation Type: Submersible probe with flush diaphragm
Housing Material: PVDF
Diaphragm Material: Ceramic Al2O3 99.9% with PTFE foil
Media Exposed Seals: FKM
Cable Type: FEP (70degC max)
Cable Length: 5
Cable Length Units: Metres (m)
Optional Extras: PTFE coated diaphragm (1% acc., 160 mbar and above, ambient temp., no vac.)

Chemical Storage and Dosing Tanks

For chemical process plants, the transmitter offers a highly reliable solution for monitoring levels in storage and dosing tanks. It is engineered to withstand the corrosive nature of aggressive media, including various acids, concentrated alkalis, and lyes. By utilizing the flush ceramic diaphragm, the device minimizes maintenance requirements while maintaining high accuracy, ensuring process safety and inventory precision in challenging chemical environments.

Potassium Hydroxide (KOH) 45% solution

Measure the level of 45% concentration potassium hydroxide solution in small storage tanks using a LMK809 with a PTFE coated Ceramic diaphragm, PP (Polypropylene) housing, EPDM seals & FEP cable configuration.

SKU ID: s1-lmk809-0011
Part No: 395-4000-R-C3-1-3-8-3-010-000
Pressure Range: 0 to 0.4 bar
Reference Type: Gauge / Vented (atm to +P)
Output Signal: 4-20mA, 2 wire
Accuracy: 1% FS
Installation Type: Submersible probe with flush diaphragm
Housing Material: PP
Diaphragm Material: Ceramic Al2O3 99.9% with PTFE foil
Media Exposed Seals: EPDM
Cable Type: FEP (70degC max)
Cable Length: 10
Cable Length Units: Metres (m)
Optional Extras: PTFE coated diaphragm (1% acc., 160 mbar and above, ambient temp., no vac.)

Hydrogen Peroxide (H2O2) 47% solution

Measure the level of 47% concentration hydrogen peroxide solution in small storage tanks using a LMK809 with a PTFE coated Ceramic diaphragm, PVDF housing, FFKM seals & FEP cable configuration.

SKU ID: s1-lmk809-0012
Part No: 395-6000-B-C3-1-7-8-3-015-000
Pressure Range: 0 to 0.6 bar
Reference Type: Gauge / Vented (atm to +P)
Output Signal: 4-20mA, 2 wire
Accuracy: 1% FS
Installation Type: Submersible probe with flush diaphragm
Housing Material: PVDF
Diaphragm Material: Ceramic Al2O3 99.9% with PTFE foil
Media Exposed Seals: FFKM
Cable Type: FEP (70degC max)
Cable Length: 15
Cable Length Units: Metres (m)
Optional Extras: PTFE coated diaphragm (1% acc., 160 mbar and above, ambient temp., no vac.)

Landfill Leachate Collection

The transmitter provides dependable level monitoring for complex landfill environments, particularly in drainage shafts and leachate collection wells. These sites often contain highly contaminated, corrosive, and potentially hazardous liquids that can damage standard equipment. The LMK809’s chemical resistance and durable construction allow it to endure these difficult conditions, providing critical data for effective environmental management and leachate processing.

Nitric acid (HNO3) 65% solution

Measure the level of 65% concentration nitric acid solution in small storage tanks using a LMK809 with a PTFE coated Ceramic diaphragm, PVDF housing, FFKM seals & FEP cable configuration.

SKU ID: s1-lmk809-0013
Part No: 395-1001-B-C3-1-7-8-3-020-000
Pressure Range: 0 to 1 bar
Reference Type: Gauge / Vented (atm to +P)
Output Signal: 4-20mA, 2 wire
Accuracy: 1% FS
Installation Type: Submersible probe with flush diaphragm
Housing Material: PVDF
Diaphragm Material: Ceramic Al2O3 99.9% with PTFE foil
Media Exposed Seals: FFKM
Cable Type: FEP (70degC max)
Cable Length: 20
Cable Length Units: Metres (m)
Optional Extras: PTFE coated diaphragm (1% acc., 160 mbar and above, ambient temp., no vac.)

Chlorine solution

Measure the level of chlorine solution in small storage tanks using a LMK809 with a PVDF housing, FFKM seals & FEP cable configuration.

SKU ID: s1-lmk809-0003
Part No: 396-1600-B-C-1-7-3-3-010-000
Pressure Range: 1.6
Units: mH2O
Reference Type: Gauge / Vented (atm to +P)
Output Signal: 4-20mA, 2 wire
Accuracy: 0.35% FS
Installation Type: Submersible probe with flush diaphragm
Housing Material: PVDF
Diaphragm Material: Ceramic Al2O3 99.9%
Media Exposed Seals: FFKM
Cable Type: FEP (70degC max)
Cable Length: 10
Cable Length Units: Metres (m)

Electroplating systems

Electroplating tanks are filled with aggressive media such as acids and alkalis which are hazardous and will cause injury to personnel and damage to surrounding equipment and structures. In order to have a safely functioning system, the level in the electroplating tank must be strictly maintained between predefined limits.

The level measuring technology used in the LMK 809 is designed for the demanding requirements of electroplating process and provides accurate measurements for the level of the contents on the electroplating tanks.

The LMK809 is also available with a choice of chemically resistant materials for the housing, seals, sensor and cable to protect from the the electroplating solutions used and the fumes that are produced from the electroplating process.

Caustic Soda solution

Measure the level of caustic soda (sodium hydroxide) solution in small storage tanks using a LMK809 with a PP-HT housing, EPDM seals & FEP cable configuration.

SKU ID: s1-lmk809-0004
Part No: 396-1600-R-C-1-3-3-3-010-000
Pressure Range: 1.6
Units: mH2O
Reference Type: Gauge / Vented (atm to +P)
Output Signal: 4-20mA, 2 wire
Accuracy: 0.35% FS
Installation Type: Submersible probe with flush diaphragm
Housing Material: PP-HT
Diaphragm Material: Ceramic Al2O3 99.9%
Media Exposed Seals: EPDM
Cable Type: FEP (70degC max)
Cable Length: 10
Cable Length Units: Metres (m)

Water Reclamation and Recycling

In industrial water treatment and reclamation facilities, the LMK809 serves as an essential component for monitoring liquid levels in sumps and holding tanks. It supports efficient reclamation processes by providing accurate, consistent pressure measurements regardless of fluctuations in water quality. Its capability to handle industrial effluents ensures that recycling systems operate within safe and optimal parameters.

Citric acid solution

Measure the level of citric acid solution in small storage tanks using a LMK809 with a PP-HT housing, FKM seals & PUR cable configuration.

SKU ID: s1-lmk809-0005
Part No: 396-1600-R-C-1-1-3-2-010-000
Pressure Range: 1.6
Units: mH2O
Reference Type: Gauge / Vented (atm to +P)
Output Signal: 4-20mA, 2 wire
Accuracy: 0.35% FS
Installation Type: Submersible probe with flush diaphragm
Housing Material: PP-HT
Diaphragm Material: Ceramic Al2O3 99.9%
Media Exposed Seals: FKM
Cable Type: PUR (70degC max)
Cable Length: 10
Cable Length Units: Metres (m)

Sodium bisulfite solution

Measure the level of sodium bisulfite solution in small storage tanks using a LMK809 with a PVDF housing, FFKM seals & FEP cable configuration.

SKU ID: s1-lmk809-0006
Part No: 396-1600-B-C-1-7-3-3-010-000
Pressure Range: 1.6
Units: mH2O
Reference Type: Gauge / Vented (atm to +P)
Output Signal: 4-20mA, 2 wire
Accuracy: 0.35% FS
Installation Type: Submersible probe with flush diaphragm
Housing Material: PVDF
Diaphragm Material: Ceramic Al2O3 99.9%
Media Exposed Seals: FFKM
Cable Type: FEP (70degC max)
Cable Length: 10
Cable Length Units: Metres (m)

Viscous Tank Level Monitoring

The LMK809 is specifically designed for hydrostatic measurement in tanks storing viscous, sticky, or settling liquids. By utilizing a flush diaphragm design, the transmitter prevents clogging and material buildup that often plague standard sensors. This ensures that operators receive reliable, uninterrupted level data even when dealing with thick, high-viscosity substances, reducing downtime and the need for frequent manual cleaning or maintenance.

Product Specifying Guide

Select nominal pressure range

Determine the maximum liquid height in the vessel and select a corresponding nominal pressure range between 0…0.4 mH2O and 0…100 mH2O (0.04…10 bar). Ensure that expected pressure surges do not exceed the specified overpressure limits for the chosen range.

Choose probe housing material

Select the appropriate housing material based on the process medium and operating temperature. Specify PP-HT housing for standard chemical applications operating within 0…60 °C, or PVDF housing for higher chemical exposure and wider temperature limits of -30…60 °C.

Select media wetted seal elastomer

Match the internal elastomeric seal to the chemical characteristics of the measured fluid. Choose EPDM for general aqueous or alkaline solutions, FKM for oils and mild chemicals, or FFKM for extreme chemical aggressiveness.

Specify cable sheath material and length

Determine the required immersion depth plus distance to the junction box, adding appropriate slack. Select PUR cable for standard wastewater applications, FEP cable for aggressive chemical fluids, or TPE-U cable for elevated temperature environments.

Evaluate accuracy and optional accessories

Choose between the standard accuracy of ≤ ±0.35 % FSO or the optional high-precision rating of ≤ ±0.25 % FSO. If required, add mounting accessories such as stainless steel terminal clamps, terminal boxes with atmospheric filters, or pipe mounting options.

Part Number Builder

Generate or decode LMK 809 ordering code

Ordering Code (Edit to Decode)

396-2500-R-C-1-1-3-2-005-000

Pressure Type

Measurement Range

Housing Material

Diaphragm Material

Output Signal

Seal

Accuracy

Electrical Connection

Cable Length (metres)

Special Version

Installation & Operation Guide

Pre-installation inspection and handling

Unpack the transmitter carefully and verify that the sensor diaphragm and cable assembly are free from physical damage. Keep the protective cap installed on the sensor head until immediately prior to mounting to prevent accidental diaphragm contact.

Mechanical mounting and immersion

Secure the transmitter using an approved terminal clamp or mounting flange, ensuring the sensor head will not bump against container walls. Lower the transmitter slowly into the fluid; striking the liquid surface rapidly can damage the ceramic diaphragm.

Protective cap removal for viscous media

If measuring high-viscosity liquids or sludges, remove the plastic protective cap from the sensor head prior to operation. Carefully lever off the cap by inserting a small screwdriver through the side holes, ensuring the screwdriver tip does not touch or scratch the ceramic diaphragm.

Electrical connection and atmospheric venting

Connect the shielded 2-wire cable to the power supply (9…32 VDC) following the color code: white wire for Supply+ and brown wire for Supply-. Route the vented cable end into a dry, clean terminal box free of aggressive gases to keep the internal atmospheric pressure reference tube unblocked and protected from moisture.

Commissioning and maintenance routine

Verify supply voltage and loop resistance before powering on the loop. Inspect the probe periodically for surface deposits or biofouling, cleaning the housing and diaphragm gently with a soft cloth and compatible liquid, taking care never to use pointed tools or compressed air on the ceramic element.

Product Help

Housing material selection for aggressive chemical media

How do I determine whether PP-HT or PVDF housing is required for my chemical application?

Choose PP-HT housing for standard wastewater or mild chemical process applications operating between 0…60 °C. For highly aggressive acids, lyes, or broader temperature environments from -30…60 °C, specify PVDF housing to ensure long-term chemical durability.

Removing the protective cap for thick sludge level measurement

Is it necessary to remove the plastic protective cap before installing the transmitter in viscous liquids?

Yes, when operating in high-viscosity media like sludge or thick effluents, the protective cap should be removed by hand or levered off carefully with a screwdriver. Removing the cap makes the ceramic sensor flush with the media, preventing clogging and allowing quick fluid contact with the diaphragm.

Ventilation tube protection for atmospheric pressure reference

Why is there an internal tube in the cable and how should the cable end be installed?

The cable includes an integrated ventilation capillary hose that provides atmospheric pressure compensation for accurate gauge pressure measurement. The end of the cable must be terminated in a dry connection box or clean environment, ensuring the filter element on the vent tube is kept undamaged and free from moisture or aggressive vapors.

Trichloroethylene tank

I need a sensor that can be used in a tank that is 6 feet 8 inches and will be filled with Trichloroethylene (Trike)?

We would suggest a 0.25 bar range LMK 809 with a PVDF housing, FFKM seals and FEP cable.

SKU ID: s1-lmk809-0008
Part No: 395-2500-B-C-1-7-3-3-005-000
Pressure Range: 0.25
Units: bar
Reference Type: Gauge / Vented (atm to +P)
Output Signal: 4-20mA, 2 wire
Accuracy: 0.35% FS
Installation Type: Submersible probe with flush diaphragm
Housing Material: PVDF
Diaphragm Material: Ceramic Al2O3 99.9%
Media Exposed Seals: FFKM
Cable Type: FEP (70degC max)
Cable Length: 15
Cable Length Units: Feet (ft)

Temperature ranges for polypropylene and pvdf housings

What are the permissible temperature limits for the LMK809 level transmitter?

For probes constructed with PP-HT housing, the medium, electronic, ambient, and storage temperature limit is 0…60 °C. For PVDF housing versions, the permissible temperature range expands to -30…60 °C.

Recommended cleaning methods for ceramic diaphragm

How should the ceramic sensing element be cleaned if deposits build up on the face?

Clean the probe housing and sensor face using a damp cloth and a mild, non-aggressive cleaning solution compatible with the wetted materials. Never touch or clean the ceramic diaphragm with sharp objects, abrasive tools, or compressed air, as mechanical force can permanently damage the sensing cell.

15 inch tall waste tank

Our waste tanks are approx. 15″ tall in height, will that meet the pressure range for the sensor?

Yes 0.4 mH2O is the lowest range, which is equivalent to 15.75 inH2O, so that should be okay as long as the waste density is similar to clean water.

50% NaOH & 32% HCl compatibility

What LMK809 configuration would we need to specify for compatibility with 50% concentration caustic soda and 32% hydrochloric acid?

Select the following materials for each chemical:

Sodium Hydroxide at 50% concentration FEP, EPDM, PP-HT
Hydrochloric Acid at 32% concentration FEP; PVDF, FFKM

Caustic Soda (30% 70 Tw) tank 1.6m high

We need a submersible sensor to measure the level of a caustic tank, 1.6m high containing 30% 70 Tw Caustic Soda solution ambient temperature.

We would suggest a combination of PP-HT housing, EPDM seals and FEP cable for the LMK809.

SKU ID: s1-lmk809-0002
Part No: 396-9999-R-C-1-3-3-3-007-000
Pressure Range: 0 to 2.124
Units: mH2O
Reference Type: Gauge / Vented (atm to +P)
Output Signal: 4-20mA, 2 wire
Accuracy: 0.35% FS
Installation Type: Submersible probe with flush diaphragm
Housing Material: PP-HT
Diaphragm Material: Ceramic Al2O3 99.9%
Media Exposed Seals: EPDM
Cable Type: FEP (70degC max)
Cable Length: 7
Cable Length Units: Metres (m)

Measurement technology type

I’m planning on using the LMK809 sensor for measuring level in a sulfuric acid tote and wanted to know if this is a submersible pressure sensor for measuring fluid level or does it use some other technique to measure level? Also how is it installed, would a port have to be cut into the bottom of the tote or could it be dropped into the tote from the top?

The LMK809 sensor measures hydrostatic pressure via a variable capacitance ceramic diaphragm sensing element which after signal conditioning generates a signal which is directly proportional to to the height of liquid above the sensor position.

The whole sensor is submersible and can be dropped into the tote from the top.

Concentrated Sulfuric acid Tote tank level

We are looking for a sensor to measure the level of conc. H2SO4 in a standard 330 gallon tote tank, what configuration would you suggest for the LMK809?

For concentrated Sulphuric acid we would suggest to choose FFKM seals, PVDF body and FEP cable options for the LMK809.

High concentration nitric acid

We are looking to measure the liquid level of a tank filled with 98% Nitric acid. The sensor will need to be submersible as it is only possible to access the tank from above. Will the LMK809 be compatible with concentrated Nitric Acid?

The LMK 809 will be compatible with concentrated HNO3 if the seal material exposed to the media is FKM, the cable is FEP coated and the housing material is PVDF. The Al2O3 Alumina ceramic diaphragm which is fitted as standard is also compatible with Nitric acid.

HCL 28% conc with 1.14 SG at room temp

I need a level sensor for lowering into a 1.6 metre high bulk acid tank containing 28% concentration HCL with a specific gravity of 1.14, and the acid will be stored at room temperature.

We would suggest a combination of PVDF housing, FFKM seals and FEP cable for the LMKK809 to use with Hydrochloric acid up to a strength of 37% at room temperature.

SKU ID: s1-lmk809-0001
Part No: 396-9999-B-C-1-7-3-3-007-000
Pressure Range: 0 to 1.824
Units: mH2O
Reference Type: Gauge / Vented (atm to +P)
Output Signal: 4-20mA, 2 wire
Accuracy: 0.35% FS
Installation Type: Submersible probe with flush diaphragm
Housing Material: PVDF
Diaphragm Material: Ceramic Al2O3 99.9%
Media Exposed Seals: FFKM
Cable Type: FEP (70degC max)
Cable Length: 7
Cable Length Units: Metres (m)

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