If you’ve ever ordered a Head Type RTD (Resistance Temperature Detector) from our team, you’ve probably noticed we get a lot of follow-up questions about humidity. It’s one of the most common pain points our customers bring up before placing a bulk order—whether they’re integrating these sensors into a food processing line in a steamy commercial kitchen, a greenhouse where humidity hovers near 90% year-round, or an industrial furnace room that swings between dry heat and sudden moisture spikes. The short answer? Yes, Head Type RTDs are resistant to humidity, but that’s a simplified explanation. Let’s break down what makes them stand up to moisture, what can still cause issues if they’re not installed right, and why our team designs ours to outperform most standard alternatives in high-humidity environments. Head Type RTD
First, let’s start with the basics of what a Head Type RTD actually is, because that’s where its humidity resistance starts. Unlike simple two-wire RTDs or bare-wire thermocouples, Head Type RTDs have a rigid, enclosed terminal head—usually made of cast aluminum, stainless steel, or even plastic for lower-temperature applications—sealed tightly around the sensor element and internal wiring. That head isn’t just a bulky add-on; it’s the first line of defense against moisture. Most people assume humidity only affects the sensor itself, but the real risk of humidity comes from condensation seeping into the connection points, corroding wires, or causing electrical shorts between the RTD’s leads. That’s the gap standard RTDs often fall into. Many cheap, unenclosed RTDs rely on thin, fragile insulation that can break down over time in high humidity, allowing water to reach the delicate platinum coil inside. Our Head Type RTDs, though, are built with a hermetically sealed terminal head in the vast majority of our models. Hermetic sealing means there’s no gap for air or moisture to pass through once the head is properly crimped and wired, which is why they’re rated for IP65 or higher ingress protection—meaning they can withstand low-pressure water jets, heavy rain, and even temporary submersion without failing.
I’ll be honest, though—we’ve had customers come to us with horror stories about humidity-related failures with RTDs they bought elsewhere, even if those were labeled “head type.” Most of the time, the issue isn’t the design of the head, but the materials and assembly shortcuts some manufacturers take. A few years back, we had a customer in the craft brewing industry reach out after a batch of their RTDs failed during a harvest season where their fermenter rooms hit 95% humidity. They were using a competitor’s Head Type RTD that had a plastic terminal head with glued seals instead of crimped, hermetic ones. The glue broke down after a few months of repeated temperature swings and high humidity, allowing condensation to pool in the head, corrode the copper lead wires, and throw off temperature readings by 10 degrees. When they switched to our Head Type RTDs, which use precision-cast stainless steel heads with compression seals and filled terminal cavities, they’ve had zero failures in that application for over three years now. That’s the kind of real-world feedback that shapes how we build every unit we ship.
Another key point about humidity and RTD performance: moisture doesn’t just cause electrical issues—it can also affect the calibration of the platinum sensor over time, if it seeps in. Platinum is incredibly stable on its own, which is why RTDs are preferred over thermocouples for accurate, long-term temperature measurement. But if moisture gets to the platinum coil and leaves mineral deposits or corrosive residue, that can change the resistance of the metal, leading to inaccurate readings. Our Head Type RTDs solve that by filling the terminal head cavity with a inert, potting compound—usually a high-temperature epoxy or silicone that’s cured to eliminate air bubbles. That potting doesn’t just hold the wires in place; it creates a second barrier between any external moisture and the internal sensor assembly. We test every single unit’s humidity resistance before it leaves our facility too. Part of our quality control process includes subjecting each batch to 1,000 hours of 85% humidity at 85 degrees Celsius, then checking for corrosion, seal integrity, and calibration accuracy. So when a customer gets our Head Type RTD, they can be confident it won’t degrade even in the most demanding high-humidity environments.
But here’s the thing: even the best Head Type RTDs won’t hold up to humidity if they’re installed wrong. We often give our customers specific installation tips, because that’s where we see the most avoidable failures. For example, if you’re mounting a Head Type RTD in an outdoor application, make sure the head is oriented so the cable gland is pointing downward. That way, if any moisture does seep past the gland seal, it will drip out instead of pooling inside the head. Another common mistake is using undersized cable glands. If the gland doesn’t make a tight seal around the cable, humidity can wick along the cable jacket into the head over time. We provide free cable gland recommendations for every RTD model we sell, so our customers don’t have to guess. We also advise against mounting the head in direct sunlight or near steam vents for applications like food processing, unless you get a head with a heat shield—another option we offer for industrial use cases.
Let’s also talk about specific use cases where our Head Type RTDs’ humidity resistance makes them the clear choice, because that’s how many of our customers evaluate their needs. Take greenhouse temperature monitoring, for example. Greenhouses have constant high humidity, often with temperature swings that cause condensation to form on every surface. A standard RTD might give a reading that’s off by 2 or 3 degrees within a few months, but our Head Type RTDs are often specified by commercial greenhouse operators because they stay accurate for years. Another common application is pharmaceutical manufacturing, where clean rooms and storage facilities have strict humidity control requirements, and temperature readings need to be precise to within 0.1 degrees Celsius. The pharmaceutical industry can’t afford a single faulty temperature reading, so they rely on our Head Type RTDs to maintain accuracy even in humid, cleanroom environments where static and moisture could cause issues with less robust sensors. We also supply RTDs for marine applications, where saltwater humidity is a constant risk—our stainless steel Head Type RTDs are rated for coastal and marine use, resisting salt corrosion and high humidity far better than brass or aluminum alternatives.
Wait, let’s address a common misconception we hear a lot: some customers think that “resistant to humidity” means the RTD will work perfectly in 100% humidity forever. That’s not the case. All sensors have a lifespan, and even our Head Type RTDs will eventually need replacement after 5 to 10 years, depending on the environment. But the difference is that our units will work reliably for that entire lifespan, rather than failing prematurely from moisture damage. We’ve also noticed that customers often compare Head Type RTDs to other temperature sensors in humid environments, like thermocouples. Thermocouples are cheaper, but they’re not nearly as accurate, and many types are more prone to corrosion in high humidity because they have exposed junctions. RTDs have a clear edge for accuracy, and our Head Type design solves their biggest vulnerability: humidity-related connection issues.
Another factor that contributes to our Head Type RTDs’ humidity resistance is the quality of the sensor element itself. We use pure platinum (99.99% purity) for all our RTD coils, which is less prone to corrosion than lower-grade metals we’ve seen in budget RTDs. We also calibrate each unit at two points (0 degrees Celsius and 100 degrees Celsius) before it ships, so we know the exact resistance-temperature relationship, which helps offset any minor effects from humidity exposure over time. For customers who need even higher humidity resistance, we also offer optional protective covers for the terminal head, which add a extra layer of defense for applications with extremely high moisture, like water treatment plants or outdoor swimming pool monitoring systems.
I’ve been working with Head Type RTDs for over a decade now, and I can tell you that humidity is still one of the most misunderstood factors in temperature sensor performance. We’ve spent years refining our design based on customer feedback and real-world testing, moving away from glued seals to compression seals, adding potting in the terminal heads, and using corrosion-resistant materials. What started as a simple way to protect connections has become a core feature that sets our RTDs apart from the competition. We don’t cut corners on materials or assembly, because we know that a failed temperature sensor can cost our customers thousands of dollars in downtime, product spoilage, or regulatory fines.
If you’re shopping for a temperature sensor for a high-humidity application, or if you’ve had bad experiences with RTDs failing from moisture in the past, our Head Type RTDs are worth a closer look. We offer custom sizing and calibration for specific applications, bulk pricing for industrial orders, and free technical support to help you choose the right model for your needs. Whether you’re a small business owner setting up a new greenhouse, a facility manager upgrading your industrial process monitoring, or a engineer designing a new pharmaceutical storage system, we can work with you to find a solution that fits your budget and performance requirements.
Don’t let humidity derail your temperature monitoring. Our Head Type RTDs are built to resist moisture, hold calibration, and perform reliably in even the toughest environments. To discuss your application and request a quote, feel free to reach out to our team directly. We’re here to help you find the right sensor for your needs.
RTD Probe References
- ASTM International. (2020). Standard Test Method forTemperature Measurement by Resistance Thermometer Elements. ASTM E1137-20, West Conshohocken, PA.
- International Electrotechnical Commission. (2018). Temperature Sensors—Resistance Thermometers for Industrial and Scientific Use. IEC 60751:2018, Geneva, Switzerland.
- National Institute of Standards and Technology. (2021). Humidity Effects on Precision Temperature Sensors. NIST Technical Note 1965, Gaithersburg, MD.
- Engineering Toolbox. (2022). Ingress Protection (IP) Ratings for Enclosures. Retrieved from industrial engineering and sensor design guidelines for moisture resistance.
Chongqing Haichen Instrument Co., Ltd.
Chongqing Haichen Instrument Co., Ltd. is one of the most professional head type rtd manufacturers and suppliers in China for over 20 years, featured by good service and competitive price. Please rest assured to buy high quality head type rtd 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/
