LMK809 Plastic Submersible Low Level Transmitter

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 (Polypropylene) 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.

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, 0-10Vdc 3 wire
  • Electrical Connection: PUR, FEP or TPE cable with IP68 watertight seal
  • Pressure Connection: Open face flush diaphragm
  • Media Compatibility: PP or PVDF sensor housing, FKM, EPDM or FFKM O ring seals and Ceramic Alumina Al2O3 (99.9%) diaphragm
  • 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

Low range level readings

The LMK 809 submersible plastic level sensor measures low pressure ranges from 1.6 to 4 metres of water gauge and has a ceramic pressure sensor element which is ideal for use with corrosive liquids.

Plastic housing

Depending on the chemical compatibility required the LMK809 PVC IP68 hydrostatic level sensor can have a PVC or PVDF sensor housing which both offer excellent compatibility for a wide range of corrosive fluids.

Cable type

Any length of PVC, PUR or FEP jacketed cable can be fitted onto the LMK-809 submersible plastic level sensor to provide chemically resistant IP68 rated electrical wiring.

Compatible seals

Depending on the temperatures and corrosion protection required FKM, EPDM or FFKM O-rings can be selected for the liquid pressure tight seals used in the LMK809 level sensors construction.

Output signal

The electrical output of the LMK 809 IP68 chemical level sensor is a 4-20mA signal which is accurate to 0.25% full scale at room temperature including linearity, hysteresis & repeatability.

Higher range level readings

For higher range pressure levels from 6 to 100 mH20 gauge the LMK807 plastic immersion level sensor is available which has the same specification as the LMK809 apart from a smaller diameter of 35mm.


Corrosive to stainless steel

Some fluids will corrode stainless steel over time and although the erosion of material is only fractions of an inch per year in many cases, this is significant when considering the thickness of level sensor diaphragms which can vary between a few thousandths of an inch to 2mm. In these types of applications ceramic sensor elements offer excellent corrosion resistance to the most aggressive media such as acid or alkaline liquids.

If you need to measure the level of a highly corrosive chemical it maybe necessary to eliminate stainless steel wetted parts entirely by constructing the sensor housing out of plastic.

To ensure a long lasting seal between the ceramic sensor element and the plastic moulding an O-ring must also be made from a compatible material such as FFKM.

Immersion in tank

If it is not possible to fit liquid level sensors to the outside of chemical storage tanks then you may have to consider using a submersible plastic level sensor. The cable will also need to be resistance to corrosive chemicals as well and cable jackets made from PVC, PTFE or FEP will need to be specified to avoid long term cable deterioration.

Product Help

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
  • Hydrochloric Acid at 32% concentration FEP; PVDF, FKM

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 housing, EPDM seals and FEP cable for the LMK809.

  • SKU ID: s1-lmk809-0002
  • Part No: 396-9999-E-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 removable nose cone
  • Housing Material: PP
  • Diaphragm Material: Ceramic Al2O3 96%
  • Media Exposed Seals: EPDM
  • Cable Type: FEP (70degC max)
  • Cable Length: 7
  • Cable Length Units: Metres (m)

Caustic Soda (NaOH) resource links

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 removable nose cone
  • Housing Material: PVDF
  • Diaphragm Material: Ceramic Al2O3 96%
  • Media Exposed Seals: FFKM
  • Cable Type: FEP (70degC max)
  • Cable Length: 7
  • Cable Length Units: Metres (m)

HCL Resource Links

Related Documents

Specification data sheet

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