High Pressure All-Metal Flow Meter for Industrial Applications
The SM Series is a high-pressure, all-metal variable area flow meter and switch that delivers rugged, reliable flow measurement where other rotameter designs cannot operate. With all-metal construction supporting pressures up to 5,000 PSIG, this industrial rotameter far exceeds the pressure limitations of glass or plastic tube designs.
The compact metal flow meter measures water based liquids or air with ±5% full scale accuracy. Engineered for demanding industrial environments, the SM Series combines variable area measurement simplicity with the durability required for air supply systems, pressurized water circuits, and industrial cooling applications. The magnetically coupled external indicator allows flow rate monitoring without requiring visibility of the internal float, while optional integrated reed switches provide automated flow monitoring and alarm capabilities.
All-Metal Construction Eliminates Glass Tube Limitations
The SM Series overcomes the limitations of glass and plastic rotameters with superior pressure capability: brass models handle up to 3,600 PSIG, while 304 stainless steel models reach 5,000 PSIG. The robust metal construction withstands mechanical shock and vibration, making it suitable for mobile equipment and industrial machinery.
Standard glass and plastic rotameters face significant operational constraints, typically limited to 100-200 PSIG and 194-400°F temperature ranges. Glass construction also presents safety hazards in high-vibration environments or system pressure shocks. Brass models offer excellent corrosion resistance for water, air, and non-aggressive fluids, while stainless steel versions provide compatibility with more corrosive media. Maximum medium temperature is 212°F (100°C) with brass or stainless steel floats and 160°F (70°C) with polypropylene floats.
Cylindrical Control Tube with V-Groove Technology
Unlike traditional tapered tube rotameters, the SM Series employs a cylindrical flow tube with precision V-groove design. This innovative measuring principle provides stable float operation across the entire flow range while enabling a more compact instrument, with direct reading scales for water and air at STP.
The cylindrical tube maintains constant float guidance, reducing measurement variability caused by off-center float positioning that affects conventional tapered tube designs. For SMO, SMW, and SMF model configurations, a calibrated restoring spring augments gravity to expand available flow range options. This spring-assisted design enables horizontal installation (SMW models) and top-to-bottom flow measurement (SMO models) that would be impossible with standard gravity-dependent rotameters.
Integrated Flow Switches with External Mounting
The SM Series offers factory-integrated reed switches providing automated flow monitoring. Switches mount externally in IP65-rated protective housings and are actuated by a permanent magnet embedded in the float, maintaining separation between electrical contacts and the measured fluid. Normally-open (N/O) reed contacts are available as standard, with SPDT contacts as an alternative option.
Up to two adjustable setpoint switches can be mounted per flow meter, with user-adjustable positions for field tuning to application-specific flow rates without requiring meter removal. According to specifications, reed contacts are rated to a maximum of 230 VDC/0.26 A/60 W or 240 VAC/0.42 A/100 W, and the switch options carry cCSAus approval.
Four Flow Direction Configurations
The SM Series provides four distinct flow direction models accommodating diverse piping orientations: vertical bottom-to-top (SMV and SMF), vertical top-to-bottom (SMO), and horizontal (SMW). Each configuration maintains the same accuracy specifications and high-pressure rating based on chosen materials, and the compact design fits tight piping runs where larger meters cannot be accommodated.
- SMV (Vertical, Bottom-to-Top): Utilizes gravity as primary restoring force, most economical option
- SMO (Vertical, Top-to-Bottom): Incorporates calibrated spring for reverse gravity flow measurement
- SMW (Horizontal Flow): Employs spring-loaded float technology for side-mounted installation
- SMF (Vertical, Bottom-to-Top with Spring): Combines spring-assisted measurement with vertical orientation
Connection sizes from 1/4" up to 1-1/4" NPT provide direct inline mounting without flanges or special adapters. Because flow direction is model-specific, the required direction should be specified along with the part number at ordering.
Made in USA and BABA-Compliant
Manufactured in Pittsburgh, Pennsylvania, the SM Series meets Build America, Buy America (BABA) compliance requirements for federally-funded infrastructure projects, with compliant models available. This ensures eligibility for municipal water treatment facilities, wastewater system upgrades, and other publicly-funded installations requiring USA-made instrumentation.
Pittsburgh-based production delivers shorter lead times compared to imported alternatives, with direct access to USA-based technical support and long-term parts availability for critical infrastructure applications.
Key Applications
The SM Series serves industrial processes where high operating pressures exceed other rotameter design capabilities, including high-pressure cooling circuits in metalworking and injection molding, machine tool pressurized coolant delivery systems, industrial welding equipment gas flow monitoring, and pressurized air supply systems.
According to specifications, listed applications also include lubrication circuits, paper-making machines, glass-melting tanks, induction furnaces, and pumps. To learn more about the underlying measurement method, see our in-depth article on variable area and rotameter flow technology.
Common Questions about SM - High Pressure All-Metal Flow Meter and Switch
A permanent magnet inside the float couples magnetically to the external indicator, so flow is read without any sight glass. The float travels in a cylindrical control tube machined with a V-groove instead of a traditional taper, which stabilizes it across the full measuring range, per the manual.
Pressure capability depends on materials: 3,600 PSIG for brass bodies and 5,000 PSIG for 304 stainless steel bodies, according to the datasheet, with polypropylene-float units limited to 230 PSIG. These ratings hold across all four flow direction models, from SMV through SMF.
According to the datasheet, SM meters operate at media temperatures up to 212°F (100°C) when fitted with metal floats, while polypropylene floats lower the limit to 160°F (70°C). Observing both the temperature and pressure limits matters: the manual cautions that operation outside them can damage the unit.
Yes. Choose the SMW for horizontal runs (left-to-right or right-to-left) and the SMO for downward, top-to-bottom flow; both rely on a calibrated return spring rather than gravity alone. SMV and SMF handle upward flow. Since orientation is fixed per model, confirm the flow direction when ordering.
Water scales start as low as 0.04...0.6 GPM and extend to 4...40 GPM, while air scales run from 0.2...1 SCFM to 5...130 SCFM at standard conditions, according to specifications. Available ranges vary by model and by connection size, which spans 1/4" to 1-1/4" NPT threads.
Optional reed switches, factory fitted, turn the SM into a flow switch with alarm capability. Setpoints are adjustable in the field along the housing rail, per the manual, so trip points can be tuned without removing the meter. A meter accepts two independently adjustable contacts, N/O standard or SPDT optional, protected to IP65.
Wetted parts, according to the datasheet, include a nickel-plated brass or 304 stainless steel body, matching fittings and slotted nozzle, and float options of nickel-plated brass, hard-anodized aluminum, polypropylene, or 304 stainless steel. Seals are NBR on brass units and FKM on stainless units, with 301 stainless steel springs.
Yes. SM Series meters are built in Pittsburgh, Pennsylvania, and BABA (Build America, Buy America) compliant models are available for projects that must meet domestic-content requirements. Domestic production also means quicker delivery than imported equivalents and direct access to US-based application and service support.
Very little. The magnetic coupling avoids wear mechanisms, so routine care is typically limited to periodic visual inspection. The manual recommends passing only clean or filtered media through the meter, noting that dirt is the instrument's primary enemy, and avoiding fluids that could corrode the 301 stainless steel spring.