What is the Difference Between Honeywell STF732 and Honeywell STF73F?

If you’re working in process control and looking for reliable flange-mounted pressure transmitters, you’ve probably come across Honeywell’s SmartLine ST700 series. Two models that often cause confusion are the Honeywell STF732 and Honeywell STF73F. At first glance, they seem quite similar—both handle the same pressure range (-700 to 700 kPa) and offer exceptional accuracy (0.05%)2. The key difference lies in their flange design and installation options. The STF732 typically offers more flexibility with various flange connections, including ANSI and DIN standards, while the STF73F models often feature specific flange configurations suited for particular applications13. Understanding this distinction helps you select the perfect transmitter for your system’s needs, ensuring optimal performance and avoiding installation headaches.

A Quick Overview: STF732 vs. STF73F

Diving Deeper into the STF732 and STF73F

Honeywell’s SmartLine transmitters are renowned for their robustness in demanding industrial environments like chemical plants and hydrocarbon processing35. The STF732 and STF73F are both stellar choices for measuring level or pressure in tanks, especially with viscous, corrosive, or crystallization-prone fluids9.

Their core superiority comes from Honeywell’s advanced “Triple Sensor” technology, which integrates differential pressure, static pressure, and temperature sensors into one unit. This allows for incredible automatic temperature and pressure compensation, ensuring that your readings are highly accurate even when process conditions fluctuate35.

Key Similarities First

It’s easier to spot the differences once you acknowledge what makes them similar:

• Performance Powerhouses: Both deliver top-tier 0.05% accuracy and a impressive 100:1 turndown ratio. This means you have immense flexibility to adjust their measurement range without sacrificing precision8.

• Rock-Solid Stability: They are designed for the long haul, boasting an annual stability of 0.04% of URL, meaning they require less frequent recalibration2.

• Communication Chameleons: You can get either model with various output protocols to match your control system, including classic 4-20mA mA, HART® (7.0), or Foundation Fieldbus™8.

• Built for Tough Jobs: With certifications like NEMA 4X/IP66/IP67 and features like comprehensive self-diagnostics and compliance with SIL 2/3 safety levels, these transmitters are built for reliability and safety in critical applications18.

So, What’s the Actual Difference?

While their core performance specs are identical, the difference lies in the mechanical design and configuration of the flange connection.

The Honeywell STF732 is generally presented as a model that offers a broader selection of flange options. It can be configured with a variety of flange standards (like ANSI Class 150 or 300, and DIN DN50-PN40 etc.), sizes (2″, 3″, or 4″), and materials (carbon steel or stainless steel)1. This makes it a highly versatile choice for integrating into various existing piping systems and specifications.

The Honeywell STF73F, on the other hand, often appears listed with a more specific focus on ANSI Class 150 flanges (typically 2″ or 3″) and commonly highlights 316L stainless steel as the flange material1. This suggests it may be streamlined for applications where that specific flange class and superior corrosion resistance are paramount.

In simple terms: Think of the STF732 as the “configurable” option for various flange needs, while the STF73F might be the “specialized” option for specific ANSI 150 applications with a strong focus on material compatibility.

Which One Should You Choose for Your System?

Your choice between the STF732 and STF73F ultimately boils down to your plant’s specific mechanical and process requirements.

Consider the STF732 if:

• Your project requires flexibility in flange standards (e.g., you need to meet either ANSI or DIN specifications).

• You need a wider range of flange sizes beyond 2″ or 3″.

• Flange material options like carbon steel (often with chromate plating) are a consideration for your design1.

The STF73F might be the better fit if:

• Your installation is specifically designed for ANSI Class 150 flanges.

• The process fluid requires the excellent corrosion resistance of 316L stainless steel at the flange connection1.

• Your application is within its specified flange size range, and you value a model potentially optimized for that standard configuration.

Always remember to consult the latest official Honeywell STF700 series selection guide or speak with a Honeywell technical sales expert to confirm the exact available configurations for your region and requirements. This ensures you get the perfect model number with the right flange, materials, and fill fluid for your application.

Beyond the Model Number: Why SmartLine?

Whether you choose the 732 or 73F, you’re investing in a transmitter designed to minimize headaches.

• Module Design: Lets you replace parts like the electronics or sensor module on-site without breaking the process seal or requiring a full unit replacement8.

• Superior Diagnostics: Built-in diagnostics help predict maintenance needs and prevent unscheduled downtime8.

• Easy Integration: These transmitters are tested for seamless compatibility with Honeywell’s Experion PKS control system, though they work equally well with other systems8.

Conclusion

The Honeywell STF732 and STF73F are not rivals; one isn’t inherently “better” than the other. They are twin pillars of performance with a subtle but crucial difference in their mechanical attachment. The STF732 offers greater configurability in flange design, while the STF73F appears more specialized for specific ANSI 150 flange connections.

By understanding this key distinction, you can make a confident decision, ensuring your next pressure or level measurement installation is perfectly matched to your system’s needs, promising accuracy, stability, and reliability for years to come.