The International Electrotechnical Commission’s (IEC’s) standard IEC 60529 (and International Organization for Standardization’s ISO 20653) identifies the ability of an electronic device (sensor) to withstand water or dust intrusion with IP68, IP69 and IP69K ratings. An IP68 product should prevent or withstand water ingression for a depth exceeding 1 meter as specified by the manufacturer for a period exceeding 30 minutes. In contrast, the highest IP rating, IP69 specifies a product (sensor) designed to withstand immersion, high-pressure jet sprays on rotation and remain stable under high water temperatures of up to 80°C.
Since IP68 leaves the specific submersion capability of the device/sensor to manufacturers, there are a variety of ways that a submersible sensor is specified. With the numerous applications for submersible sensors of all types, users need to carefully investigate the manufacturer’s product claims and guarantees.
For example, submersible sensors are widely used in the maritime applications and the oil and gas industry to provide accurate, high-quality force data. In addition to keeping out water, maritime measurement solutions need to be sealed to keep out debris like sand, too.
Image: Maritime – Interface (interfaceforce.com)
IP-rated submersible force solutions are essential for these applications. The load cells can survive through underwater submersions at different capacities and still be able to relay information to those at the surface level. For the maritime applications, standard submersible products as well as custom solutions can be designed to the exact specification and expected conditions.
An interesting example is wave tank hydrofoil design for watercraft specifically that requires a delicate balance between performance and complexity. Determining the right shape to achieve the desired amount of lift is essential to design a successful hydrofoil. To verify the subtle differences between hydrofoil designs, a submersible 3-axis load cell is needed to read the forces: Fz senses lift and the Fx and Fy sense the drag.
Stainless steel is used to meet submersible application requirements and provide rugged designs for different temperatures and climates. Other examples of maritime applications for submersible-rated force sensors include:
- Commercial fishing wire testing
- Mooring tension testing
- Mooring quick release hooks
- Crane block safety check
- Crane capacity verification
- Crane force regulation
- WTS yacht rigging inspection
- Weight and tension monitor
- Motor and engine testing
- Submersible equipment tests
- Defense submersible test
Submersible sensing probes are also required for immersion in freshwater, seawater or any other compatible liquid to measure liquid temperature. Temperature sensing probes offered for these applications achieve media compatibility by using 316 stainless steel or CA104 marine bronze housings. Their submersible rating is specified to a pressure rating of 5 bar (72.5 psi, 50 mH2O) or a depth of 167 feet in water.
Submersible integrated electronic piezo electric (IEPE), piezoelectric sensors with built-in electronics, are available with IP68 protection to around 100 meters. One submersible IEPE accelerometer designed for harsh environments employs a welded Titanium housing. It has an integral cable that is custom designed for submersible applications and uses a unique water block feature that self-seals if accidental cuts to the cable occur.
Submersible pressure transducers for underwater use are sometimes called borehole transducers or tank level sensors. To survive the environments, they use high strength stainless steel construction to achieve IP68 protection.
References
IP68 VS IP69: Is IP69 Necessary? – ruggedt
Maritime – Interface (interfaceforce.com)
MARITIME Hydrofoil Testing in Wave Tank – Interface (interfaceforce.com)
STT-26 Submersible Temperature Probe and Transmitter (sensorsone.com)
MODEL 8042 SUBMERSIBLE ACCELEROMETER (swautomatik.se)
Submersible Pressure Transducers | Variohm
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