DID YOU KNOW?
How Turbine Meter Fittings Affect the Pressure Rating of FLOMEC® G2 Series Flow Meters
What You Should Know About selecting the perfect turbine meter for your SYSTEM
flanges, clamps, gaskets, and temperature conditions all play a role in Selecting the Perfect Turbine meter for YOUr SYSTEM
It is important to always confirm the lowest-rated component in the installed meter assembly.
"Did You Know?"
What You Should Know About selecting the perfect turbine meter for your SYSTEM
As a point of reference, G2 Stainless Steel meters with NPT, ISO, or BSPT threaded connections are rated for 1,500 psi. That rating provides a useful comparison when looking at other connection styles, because flanged and sanitary clamp versions are limited by the connection hardware rather than the meter body itself.
When selecting a G2 Series turbine flow meter, it is easy to focus on the meter body material and published pressure rating. However, the connection style on the ends of the meter can become the limiting factor. That is why G2 data sheets list 150# ANSI flange models as “Flange Rule” and sanitary clamp models as “Limited by fitting, clamp size, & temperature.”
150# ANSI Flange Models
For G2 flow meters supplied with 150# ANSI flanges, the meter assembly is not simply rated by the stainless-steel meter body. The allowable working pressure is determined by the applicable flange standard and the flange's pressure-temperature rating at the operating temperature. In practical terms, the flange connection sets the pressure limit, so customers should verify the pressure-temperature rating of the mating flange system before installation.
The table below provides reference values to illustrate how increasing temperature can reduce the pressure rating of a Class 150 ANSI flange compared to the 1,500 psi rating of G2 stainless steel flow meters with threaded connections. These values are intended for general educational purposes only. FLOMEC does not publish pressure ratings for flanged installations because the final assembly pressure rating depends on factors outside our control, including flange material, gasket selection, mating components, installation practices, and applicable pressure-temperature standards.
| Operating Temperature | Estimated 150# ANSI Flange Rating | Effect vs. 1500 psi Threaded Rating | Customer Meaning |
|---|---|---|---|
| Ambient (-20°F to 100°F) | 275 psi | 18% of 1500 psi | The flange connection reduces the allowable pressure well below the threaded meter rating. |
| 150°F | 255 psi | 17% of 1500 psi | Rising temperature begins to reduce the allowable flange pressure. |
| 200°F | 235 psi | 16% of 1500 psi | Higher temperatures further reduce the allowable flange pressure. |
| 250°F | 225 psi | 15% of 1500 psi | The flange rating continues to decline as operating temperature increases. |
Important: The 150# flange class does not mean the flange is rated for 1500 psi. In this example, the estimated flange limit is approximately 275 psi at ambient temperature and approximately 225 psi at 250°F. The actual allowable pressure depends on flange material, gasket, mating components, and operating temperature, so the installed meter assembly must be rated by the lowest-rated component in the system.
Sanitary Clamp Models
For G2 flow meters with sanitary clamp connections, the pressure rating depends on the complete clamp joint, not just the meter body. Fitting design, clamp size, gasket material, clamp style, and process temperature can all reduce the maximum allowable pressure. Since these components can vary from one installation to another, the datasheet correctly states that the rating is limited by the fitting, clamp size, and temperature.
Sanitary clamp pressure ratings can vary widely because the connection is an assembly made up of two ferrules, a gasket, and a clamp. The “weakest link” may be the clamp at higher pressures, the gasket at higher temperatures, or the ferrule/fitting geometry in applications with larger sizes, reducers, or nonstandard components.
| Sanitary Clamp Factor | How It Can Affect Pressure Rating | Customer-Friendly Example |
|---|---|---|
| Fitting design | Ferrule shape, wall thickness, reducers, adapters, and special fittings can change how force is carried through the joint. | A straight weld ferrule may support a higher-rating assembly than a thin-wall adapter or specialty transition fitting. |
| Clamp size | Larger clamp sizes often carry lower pressure ratings because the same pressure acts over a larger area and creates more separating force at the joint. | A small 3/4 in. or 1 in. clamp assembly may be rated much higher than a 2-1/2 in. clamp assembly of similar style. |
| Gasket material | Each gasket material has its own temperature and chemical limits. At elevated temperature, some gasket materials soften, creep, or lose sealing force. | EPDM, Buna, FKM, silicone, and PTFE gaskets do not all have the same temperature range or sealing behavior. |
| Clamp style | Clamp construction has a major effect on pressure capability. Standard clamps, heavy-duty clamps, three-segment clamps, and double-bolt high-pressure clamps can have very different ratings. | A high-pressure double-bolt clamp may be appropriate where a standard hinged clamp is not. |
| Process temperature | Temperature can reduce both clamp assembly rating and gasket performance. The joint must be evaluated at the actual operating temperature, not just room temperature. | A clamp assembly suitable at 70°F may have a lower allowable pressure at 250°F or during CIP/SIP conditions. |
As a practical example, published sanitary clamp references commonly show that high-pressure clamp ratings can drop as clamp size increases and can also be lower at elevated temperature. Gasket references also show that materials such as Buna, EPDM, PTFE, and FKM have different usable temperature ranges. That is why sanitary clamp G2 meters should always be reviewed as a complete installed assembly. FLOMEC does not publish pressure ratings for sanitary fitting installations because the final assembly pressure rating depends on factors outside our control. It is the installer's responsibility to identify the "weakest link" that determines the maximum allowable pressure for the entire assembly.
Customer Takeaway
The G2 meter body may be capable of operating at a higher pressure than the installed end connection allows. Always confirm the lowest-rated component in the installed assembly, including flanges, clamps, gaskets, and temperature conditions. The lowest-rated component determines the safe working pressure of the meter installation.
