Selecting the right submersible instrumentation is crucial for long-term reliability and accuracy in demanding underwater applications. This guide highlights the key design considerations, from material selection to sealing techniques, that ensure your instruments can withstand continuous submersion and deliver precise measurements.
This selection guide is focused on choosing instrumentation designed for complete submersion in liquids, specifically those meeting the stringent requirements of IP68 ratings. This goes beyond simple waterproofing, demanding robust construction to withstand prolonged exposure and hydrostatic pressure.
LMP307 Submersible Level Transmitter - Submersible level transmitter for measuring liquid level with a 4-20mA current loop or a 0-10V voltage output plus optional ATEX approval for intrinsically safe use in hazardous areas in ranges from 1mH2O up to 250mH2O. The LMP307 is suitable for use on potable water with no leaching, and can be supplied with a drinking water certificate according to DVGW and KTW.
DMK457 Marine Approved Pressure Transmitter - Marine approved pressure transmitter with 4-20mA current loop output for shipbuilding with optional CuNiFe housing for sea-water compatibility
LMK458 Marine Approved Hydrostatic Level Transmitter - Marine approved level transmitter with 4-20mA output for measuring level of contents inside ship ballast, fuel, liquid cargo or wastewater tanks
18.605 G Low Cost Submersible Diesel Fuel and Water Tank Level Sensor - Low cost OEM diesel fuel or water level sensor for installing inside or outside a storage tank. 
STT-26 Submersible Temperature Probe and Transmitter - Submersible 4-20mA output sensing probe for immersion in freshwater, seawater or any other compatible liquid to measure liquid temperature.
36XW Digital Submersible Hydrostatic Level Sensor - The 36 X W is a high accuracy sensor with analogue 4-20mA / 0-10Vdc or digital RS485 output for submersing into a liquid to measure depth.
- Contaminated groundwater submersible plastic body 5 psi pressure transducer & display
- Underground rain water storage tank level sensor and readout for 2 metre depth
- 200m deep well pump water level sensor, switch & display
- Borehole drawdown low voltage power supply 25m depth sensor
- Potable water underground 10ft dia storage tank temperature and level sensor
- Lightning protected submersible level sensor for hydroelectric intakes and rivers
- Submersible Liquid Level Sensors - Explore submersible liquid level sensors designed for continuous fluid immersion. Learn about hydrostatic measurement, IP68 sealing, vented cable technology, and applications.
Underwater Pressure Sensors - Explore IP68-rated underwater pressure sensors designed for continuous submersion. Ideal for ballast tank level, subsea system monitoring, and hollow structure flood detection.
Submersible Pressure Transmitters - Submersible pressure transmitters offer reliable and accurate measurements in challenging underwater environments. With 4-20mA output and IP68 ratings, these robust sensors excel in monitoring liquid level, water depth, and pressure in submerged applications.
Hazardous Area Submersible Hydrostatic Liquid Level Sensors - Explore our range of intrinsically safe (IS) submersible hydrostatic level sensors, designed for accurate liquid level measurement in hazardous environments
Submersible Leachate Level Transmitters - Submersible leachate level transmitters are essential tools in environmental monitoring, especially in landfill and waste management applications.
Water Resistant Pressure Sensors with Strain Gauge Output - Explore our range of submersible pressure sensors engineered with strain gauge technology. These sensors excel in demanding underwater environments, offering accurate hydrostatic level measurements and reliable pressure readings for submerged systems.
Find out more about our Submersible to determine which product options and capabilities will best meet your application requirements.
The primary concern for any submersible device is preventing liquid ingress. Unlike surface-mounted instruments, points of weakness such as seals, joints, and even the materials themselves become critical failure points when continuously immersed. This guide focuses on the design considerations essential for reliable underwater operation.
Material selection is paramount. Submersible instrumentation must be constructed from materials that exhibit exceptional corrosion resistance to the specific liquid in which they will operate. This is not limited to just water; many industrial applications involve aggressive chemicals. Corrosion can compromise material integrity, leading to leaks or interfering with the precise sealing required between components.
The seals themselves are a crucial element. They must be pressure leak-tight, maintaining their integrity under the hydrostatic pressure exerted by the surrounding liquid. Furthermore, these seals must demonstrate resilience to temperature fluctuations, which can cause expansion and contraction, potentially compromising the seal. Finally, the seal material itself must resist corrosion from the immersion fluid.
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For deeper submersion applications, the design often incorporates multiple layers of protection. This might include a series of seals, each providing a barrier against ingress. In addition, internal cavities may be backfilled with a potting compound or other inert fill material. This serves two purposes: it eliminates air pockets that could be compressed at depth, and it provides a final layer of defense against liquid intrusion, even if the primary seals are compromised.
The choice of potting compound or fill material is itself a critical design consideration. It must be chemically compatible with both the internal components and the external fluid, and it must maintain its properties over the expected temperature range and operational lifetime of the instrument. Permeation, the slow passage of liquid molecules through a solid material, is also a design element that is taken into consideration.
Typical installation examples include, monitoring the contents of underground water storage tanks, measuring effluent levels in open air waste processing tanks, and borehole water abstraction level monitoring. Deep sea oil and gas production monitoring requires highly specialised submersible instrumentation, which often incorporates extra protection from seawater corrosion, marine growth, and the effects of impact from fast moving debris.
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