What Is the KOBOLD DIH Rotating Vane Flow Indicator?
The KOBOLD DIH is a compact rotating vane flow indicator that provides clear visual confirmation of liquid flow without electrical power. A high-visibility orange polypropylene paddle wheel rotates behind a transparent PMMA (acrylic) cover, indicating flow presence and relative flow activity in water-based liquids across eight ranges from 0.05 to 13.2 GPM.
Available in three housing materials (nickel-plated brass, 316L stainless steel, or POM) the indicator accommodates diverse liquid flow applications, from general water service to corrosive chemical environments. The DIH is Made in USA, and BABA compliant models are available for federally funded projects.
Flow Ranges and Performance Specifications
The DIH addresses low to medium flow rate applications for water-based liquids, with eight available flow ranges spanning 0.05 to 13.2 GPM (0.2 to 50 liters per minute). All housing configurations are rated to 230 PSI (16 bar) maximum pressure and 176°F (80°C) maximum temperature according to specifications.
This lower flow capability makes the DIH particularly suitable for dosing verification, small cooling systems, or leak identification. Connection options include 3/8 inch NPT for compact installations and 1 inch NPT for higher flow ranges. The pressure drop at maximum flow remains at 14.5 PSI, minimizing impact on system hydraulics.
Housing Material Options for Application Compatibility
The DIH is offered in three housing series: DIH-11 in nickel-plated brass with NBR seals, DIH-12 in 316L (1.4404) stainless steel with FKM seals, and DIH-13 in POM with NBR seals. Every version shares the same PMMA cover, polypropylene rotor, ceramic axle, and identical pressure and temperature ratings.
DIH-11: Nickel-Plated Brass
The DIH-11 series features nickel-plated brass housing, offering moderate corrosion resistance, paired with NBR seals compatible with water, oils, and many common industrial fluids. This configuration suits general industrial applications where enhanced corrosion protection is desired without the cost of stainless steel.
DIH-12: 316L Stainless Steel
The DIH-12 series utilizes 316L stainless steel housing for exceptional corrosion resistance. FKM seals extend chemical compatibility to aggressive fluids and elevated temperatures. This material combination is frequently specified in water treatment facilities and industrial plants requiring BABA compliant instrumentation with superior corrosion resistance.
DIH-13: POM
The DIH-13 series employs POM housing, a high-strength engineered plastic, offering lightweight construction and good chemical resistance. NBR seals complement the POM housing for cost-effective applications with compatible fluids. This configuration provides the most economical option while maintaining the same pressure and temperature ratings as the metal housings and full BABA compliance.
Made in USA - Build America, Buy America Act (BABA) Compliance
The KOBOLD DIH compact rotating vane flow indicator is Made in USA and fully compliant with Build America, Buy America Act (BABA) requirements. Manufactured at KOBOLD's Pittsburgh, Pennsylvania production facility, this domestically produced flow indicator qualifies for federal infrastructure programs, water utility upgrades, and public sector projects requiring domestic content certification.
Compact, Space-Saving Design
The DIH's compact square housing measures just 3.3 inches (84 mm) in length for 3/8 inch NPT models and 4.3 inches (110 mm) for 1 inch NPT models. This minimal footprint enables installation in equipment compartments, control panels, machinery housings, and piping manifolds where conventional flow indicators would interfere with adjacent components or exceed available clearance.
Maintenance-Free Mechanical Operation
The DIH operates as a purely mechanical indicator without electrical connections, power supplies, batteries, or electronics. The presence or absence of rotary motion indicates whether there is flow or not. No routine maintenance is required beyond periodic visual inspection to verify the window remains clean and the rotor spins freely.
The ceramic axle material resists wear and corrosion, while the polypropylene rotor remains unaffected by most aqueous solutions and many chemicals. The PMMA cover resists scratching and maintains optical clarity for visual observation throughout its service life. This simplicity provides inherent reliability and helps reduce lifecycle costs and maintenance labor requirements.
Installation Guidelines
According to the manufacturer's operating instructions, the DIH should be mounted tension-free into the pipe, and the rotating vane axle should be vertical after installation. Water hammer in the measuring tube (for example, caused by a very quick shutoff of the flow) should be avoided, and the maximum operating pressure and temperature must not be exceeded.
Learn more about paddle wheel flow technology by visiting our in-depth Article on Paddle Wheel Flow Technology.
Paddle Wheel Flow Technology
Learn more about paddle wheel flow technology by visiting our in-depth Article on Paddle Wheel Flow Technology.
Common Questions about DIH - Rotating Vane Flow Indicator
The DIH is available in eight ranges for water, from 0.05...0.13 GPM at the low end up to 0.26...13.2 GPM at the high end, approximately 0.2 to 50 liters per minute overall. This span is designed to serve low to medium flow applications such as dosing verification and small cooling circuits.
All three housing versions (nickel-plated brass, 316L stainless steel, and POM) carry identical ratings according to specifications: a maximum pressure of 230 PSI (16 bar) and a maximum temperature of 176°F (80°C). The pressure drop at maximum flow is 14.5 PSI for all configurations.
Yes. The DIH is Made in USA at KOBOLD's Pittsburgh, Pennsylvania production facility, and BABA (Build America, Buy America Act) compliant models are available. It qualifies for federal infrastructure programs, water utility upgrades, and public sector projects that require domestic content certification.
No. The DIH is a purely mechanical device with no electrical connections, power supplies, batteries, or electronics. Flow is shown visually: when liquid moves through the housing, the orange polypropylene vane rotates behind the transparent PMMA window, and when flow stops, the rotation stops.
Three combinations are offered: DIH-11 with nickel-plated brass housing and NBR seals, DIH-12 with 316L (1.4404) stainless steel housing and FKM seals, and DIH-13 with POM housing and NBR seals. All versions use a PMMA (acrylic) cover, a polypropylene rotor, and a ceramic axle.
The DIH connects via 3/8 inch NPT threads (ordering code N10) or 1 inch NPT threads (ordering code N25). Housing length is 3.3 inches (84 mm) for the 3/8 inch NPT models and 4.3 inches (110 mm) for the 1 inch NPT models.
The manufacturer's instructions call for mounting the indicator tension-free in the pipe, with the rotating vane axle vertical after installation. Avoid water hammer caused by very quick flow shutoff, remove all packing materials before installation, and check directly afterward that the connection thread to the pipe is fully sealed.
Routine maintenance is limited to periodic visual inspection: confirm the PMMA window remains clean and the rotor spins freely. The wear-resistant ceramic axle and chemically resistant polypropylene rotor are designed to provide long service life with minimal friction, helping reduce lifecycle costs and maintenance labor requirements.