Hey there, if you’ve ever ordered a custom RTD sensor from us (or any sensor supplier, for that matter) and thought, “I wonder how this thing holds up in salty environments,” you’re not alone. Salt spray isn’t just a nuisance for your boat’s metal parts—it’s a silent destroyer of temperature sensors, and it’s one of the most common questions we get from folks using RTDs in coastal factories, offshore rigs, food processing plants that use brine, or even climate control systems near the ocean. Let’s break this down like we talk to our clients every day, no stuffy jargon, just real, actionable info that helps you make the right call for your project. RTD Sensor
First, quick refresher for anyone who’s new to RTDs—they’re those little temperature sensors that work on the principle that metals change resistance as temp shifts, right? Most are made of platinum, which is why they’re so accurate and popular for long-term use. But platinum is tough, not unbreakable, especially when salt spray gets involved. Salt spray is basically tiny, fine droplets of salt (usually sodium chloride) suspended in air, and it’s way more corrosive than regular moisture because salt is an electrolyte. It speeds up chemical reactions that eat away at metal, and that’s where the damage starts for RTDs.
Let’s get into the actual effects, step by step, because it’s not just “it rusts.” The first big issue is what we call surface corrosion, but more specifically, the lead wires and the platinum element itself can break down over time. Wait, the platinum in an RTD is super thin—like, for a standard Pt100, the wire is only a few microns thick, right? That’s thinner than a human hair. Salt spray gets into the small gaps between the sensor’s protective coating (more on that later) and starts eating at that thin wire. At first, you might not notice anything—like, the resistance might still read close to what it should, so you think everything’s fine. But over weeks or months, that corrosion creates tiny pits on the platinum wire, and eventually, those pits turn into breaks. When that happens, your RTD will start giving wild, inaccurate readings—like, it’ll say the unit is 20 degrees colder than it actually is, or just flatline. We had a client last year who runs a seafood processing plant in Maine; their original RTDs were cheap, uncoated, and only lasted 6 months in the brine washers. They thought they were getting faulty sensors at first, but it was just the salt spray eating through the lead wires.
Another effect we see all the time is coating degradation. Most off-the-shelf RTDs come with a basic protective jacket—sometimes epoxy, sometimes a thin metal sheath. But salt spray is persistent. It gets into tiny scratches in the coating, or just wears it down over time if the sensor’s exposed to constant air flow with salt in it. Once the coating is breached, that salt gets right to the sensor’s innards. We’ve had clients send back sensors with what looks like white powdery salt deposits inside the sheath— that’s salt creep, and it’s a sign the coating didn’t do its job. The bad part here is that salt creep doesn’t just corrode metal; it can also cause electrical shorts. If two lead wires get bridged by salt deposits, the resistance reading will jump all over the place, and your control system might shut down unexpectedly. That’s a big problem for clients running things like HVAC systems in coastal hotels—you can’t have your AC cutting out because a sensor’s shorted.
Wait, let’s not forget about the calibration shift. Even if corrosion doesn’t fully break the wire or cause a short, it can still mess up the RTD’s accuracy. When salt eats at the platinum, it changes the resistance of the wire slightly over time. For example, a brand new Pt100 should have 100 ohms at 0°C. After 12 months in moderate salt spray, that same sensor might measure 101.2 ohms at 0°C, which translates to a temp error of about 3°C. That might not sound like much, but if you’re running a chemical reactor where temp control is critical, or a refrigeration unit keeping perishable goods, 3 degrees can be the difference between a safe product and a spoiled one. We had a food manufacturer that had to throw out $50k worth of frozen shrimp because their RTD readings were off by 4 degrees—they’d used a basic, uncoated sensor that shifted because of salt spray in the cold storage area. Ouch.
Now, let’s talk about what we actually do at our shop to counter this, because we’re not just a supplier—we’re here to solve problems. We don’t sell one-size-fits-all RTDs for salt spray environments; we customize based on how salty the application is. For mild salt exposure, like coastal office HVAC or equipment near the beach that’s not directly hit by spray, we use epoxy-coated lead wires and a stainless steel 304 sheath. 304 is better than plain steel, but it’s not perfect for heavy salt. For medium exposure, like boat engine rooms or seafood processing lines, we bump up to a 316L stainless steel sheath. 316 has molybdenum in it, which makes it way more corrosion-resistant to salt—think of it like regular steel vs. a rust inhibitor. For heavy exposure, like offshore oil rigs, desalination plants, or sensors that are fully submerged in brine (not just sprayed), we add a PTFE coating over the 316 sheath, or even use a hermetically sealed design. Hermetic sealing means the sensor is completely airtight, so salt spray can never get to the innards—we weld the sheath shut and test it for leaks before it leaves our shop. That’s been a game-changer for our offshore clients; their sensors now last 5+ years instead of 6 months like the cheap ones they used before.
Wait, but here’s a common mistake clients make: they think “stainless steel is stainless steel, so any 316 will work.” Nope, not all 316 is the same. Some manufacturers cut corners and use lower-grade 316 that doesn’t have the right molybdenum content, so it still corrodes in heavy salt. We source our 316 from trusted suppliers, and we test every custom sensor for salt spray resistance in our own lab before it ships. We have a salt spray chamber that simulates 1,000 hours of constant salt exposure— that’s like 5 years of real-world coastal use, basically. If a sensor passes that test, we know it’s going to hold up.
Another thing people don’t talk about is installation. Even the best RTD in the world will fail if you install it wrong in a salt spray environment. For example, if you mount the sensor in a spot where salt water pools around the connector, that’s a dead spot. We always advise clients to use weatherproof connectors, seal every cable entry with a marine-grade sealant, and avoid mounting sensors in low areas where salt can collect. We even include a free installation guide with every custom salt-resistant RTD we sell, because the sensor itself is only half the battle.
Let’s wrap this up with a real example that’s fresh on our minds. A client who runs a series of desalination plants in the Gulf Coast came to us last year. They were using off-the-shelf RTDs that were failing every 8 months due to salt spray corrosion on the lead wires. They tried switching to a big name brand, but those still only lasted 10 months. They reached out to us, we customized them with hermetically sealed 316L sheaths and PTFE-coated leads, and now those same sensors are going on 2 years with zero issues. They just ordered another 200 units last month, and their maintenance team says they haven’t had to replace a single one. That’s the difference between a custom sensor that’s built for your specific environment and a generic one.
If you’re working with RTD sensors in a salty environment—coastal industrial sites, marine equipment, food processing with brine, HVAC near the ocean, or anything exposed to salt spray and salt creep—you don’t have to deal with constant sensor failures and inaccurate readings. We build custom RTDs tailored to your exact salt exposure level, test each one in our salt spray lab, and include the support you need to install it right. No one-size-fits-all, no fake promises, just sensors that actually work in tough conditions. If you’re tired of replacing RTDs every few months or dealing with temp readings that are off because of salt spray, hit us up to chat about your project needs. We’ll walk you through our options, answer any questions you have, and make sure you get a sensor that lasts.
Bimetallic Thermometer References:
- “Corrosion of Metals in Marine Environments,” NACE International, 2021.
- “Platinum RTD Sensor Performance in Corrosive Atmospheres,” ISA Transactions, vol. 92, 2020, pp. 112-120.
- “Salt Spray Testing Guidelines for Industrial Sensors,” ASTM B117-19, 2019.
- “Corrosion-Resistant Materials for Temperature Sensors,” Journal of Sensors and Actuators A: Physical, vol. 301, 2019, 111765.
Chongqing Haichen Instrument Co., Ltd.
Chongqing Haichen Instrument Co., Ltd. is one of the most professional rtd sensor manufacturers and suppliers in China for over 20 years, featured by good service and competitive price. Please rest assured to buy high quality rtd sensor for sale here from our factory. For customized service, contact us now.
Address: No.11 Gusheng Road, Caojie Street, Hechuan District, Chongqing City, P.R. China
E-mail: sales@hcsensor.com
WebSite: https://www.hcsensor.com/
