DRG Electronic Paddle Wheel Flow Sensor
The KOBOLD DRG is an electronic paddle wheel flow sensor that measures liquid flow through non-contact Hall effect sensing and offers frequency, 4-20 mA, or on-sensor display outputs in six material combinations. It provides visual flow indication and electronic signals that integrate directly into control systems and automated monitoring, and is designed for OEM applications where compact size and economical pricing matter.
The paddle wheel principle delivers reliable flow sensing at a fraction of the cost of magnetic flow meters or ultrasonic instruments, making the DRG a practical choice when budget constraints limit more expensive technologies. For OEM programs that repeat across multiple units or product lines, its economical pricing enables electronic monitoring without prohibitive instrumentation costs.
How the DRG Measures Flow
The DRG works on the rotating vane principle: permanent magnets embedded in the paddle wheel pass a Hall-effect sensor with each revolution, generating clean pulses proportional to flow rate. Because the sensing is non-contact, there are no wear mechanisms to degrade accuracy, and the hermetically sealed electronics stay isolated from the liquid while maintaining IP65 protection.
This magnetic coupling transfers rotational information without physical contact, keeping signal quality consistent over the sensor's service life. Isolating the sensing electronics from the wetted path prevents corrosion or chemical degradation of the components, supporting reliable measurement even in demanding process environments.
Six Material Combinations for Chemical Compatibility
The DRG is offered in six material combinations that address different chemical compatibility needs. Brass housings suit water, coolants, and compatible process fluids; stainless steel extends resistance for more demanding media; and all-plastic polypropylene and polysulfone versions provide a fully compatible wetted path for high purity water and aggressive chemicals — a configuration rarely available in electronic paddle wheel sensors.
Every combination uses a PTFE paddle wheel for broad chemical resistance with low-friction rotation, and a ceramic axle for wear resistance and dimensional stability across the operating temperature range. NBR or FKM O-ring options let you match the seal to the fluid and its temperature.
Output Options and System Integration
The DRG offers several electronic outputs so designers can select the right interface for each application. Frequency models produce pulses proportional to flow for direct connection to counters, PLCs, or totalizers. Analog models deliver 4-20 mA in 2-wire or 3-wire configurations for process controllers, chart recorders, and SCADA. Compact-electronics models add a 3-digit LED display with programmable switch contacts.
The current-loop output resists electrical noise and voltage drop over long cable runs. Frequency versions draw about 10 mA at 12-28 VDC, or 15 mA for frequency-divider versions at 24 VDC; analog and compact-electronics versions run on 24 VDC, with the compact display drawing roughly 100 mA. Connection is by M12 circular or DIN 43650 connector for quick-disconnect installation.
Flow Ranges, Pressure, and Temperature
The DRG covers liquid flow from 0.15-3 GPM up to 3-37 GPM across six range configurations, with 1/8" through 1" NPT connections. Maximum operating pressure depends on the housing-and-cover pairing, temperature capability reaches 176°F (80°C) across all combinations, and accuracy is ±3% of full scale — sufficient for flow verification, batching, and process monitoring.
- Polypropylene housing with polypropylene cover: 100 PSIG
- Polypropylene housing with polysulfone cover: 160 PSIG
- Brass or stainless steel housing with polysulfone cover: 230 PSIG
- Brass or stainless steel housing with brass or stainless steel cover: 580 PSIG
Pressure drop at 100% of rated flow is typically 14.5 PSI, allowing inline installation without excessive flow restriction. Overall length stays compact, from about 3.15 inches for 1/8" through 1/2" connections to 3.93 inches for 3/4" and 1" connections.
Installation and OEM Integration
The DRG installs inline with the rotor axle in the horizontal plane and the housing kept continuously filled with liquid; in the horizontal orientation the display faces the side of the meter. No straight upstream or downstream pipe runs are required, which simplifies layout. To protect the connections, brace the inlet and outlet piping about 2 inches (50 mm) from the fitting.
Its small footprint adds minimal length to a pipe run and needs no external mounting brackets, reducing installation hardware. Together with selectable outputs and economical pricing, these traits make the DRG straightforward to design into manufactured equipment without custom engineering.
Made in the USA and BABA Compliance
The DRG is made in the USA, with production in Pittsburgh, Pennsylvania. That domestic manufacturing is an advantage where domestic sourcing is preferred or required, and BABA (Build America, Buy America) compliant models are available. Equipment sold to federal agencies, government facilities, and municipally funded infrastructure projects can incorporate the DRG to meet domestic-content requirements where applicable.
Applications Across Liquid Handling Industries
The DRG serves electronic flow measurement in cooling water systems, chemical dosing, process liquid monitoring, high purity water distribution, and equipment lubrication. Manufacturing equipment uses it for coolant flow verification and automated process control, and water treatment systems rely on it for flow measurement and totalizing. Its output flexibility and material options suit both standalone monitoring and embedded OEM roles.
Common Questions about DRG - Paddle Wheel Flow Sensor
It operates on the rotating vane principle for low-viscosity liquids. A magnet sealed inside the spinning vane transfers rotation to a Hall-effect sensor in the housing, which produces a frequency proportional to flow rate. A series-connected electronics unit then converts that signal into an analog output, switch contacts, or a display reading.
The DRG measures liquid flow from 0.15...3 GPM to 3...37 GPM, offered as six flow-range versions so you can match the sensor to your expected duty. Process connections are NPT threads in five sizes from 1/8" to 1", letting the meter fit a wide span of pipe diameters.
Temperature capability is 176°F (80°C) for every material combination. Maximum pressure depends on the housing and cover: 100 PSIG for all-polypropylene, 160 PSIG for polypropylene with a polysulfone cover, 230 PSIG for a metal housing with a polysulfone cover, and 580 PSIG for a metal housing with a metal cover.
Three output families cover most integration needs: frequency (pulse) output for counters, PLCs, and totalizers; 4-20 mA analog in 2-wire or 3-wire form for controllers, recorders, and SCADA systems; and compact electronics that combine a 3-digit LED readout with programmable setpoint switches. Analog versions support loads up to 500 Ω.
Six combinations are available. Housings come in brass, stainless steel, or polypropylene, with covers in brass, stainless steel, polysulfone, or polypropylene. Every version uses a PTFE paddle wheel and ceramic axle, and you choose NBR or FKM O-rings to suit the fluid. All-plastic builds suit high-purity water and demanding chemical media.
The DRG holds ±3% of full-scale accuracy, appropriate for verifying flow, dosing and batching duties, and routine process monitoring. Its pressure drop reaches about 14.5 PSI at 100% of rated flow, so the meter can sit inline without heavily restricting the system it measures.
Installation is simple and needs no flow conditioning. Orient the unit so its rotor axle lies horizontally, and keep the body full of liquid during operation — important for downward flows. Because no inlet or outlet straight runs are required, the meter fits tight layouts; support the adjoining pipework near the fittings to avoid strain.
Power depends on the electronics: frequency versions run on 12-28 VDC (about 10 mA, or 15 mA with a frequency divider), while analog and compact-display models use 24 VDC, the display version drawing near 100 mA. Wiring lands on an M12 circular plug or a DIN 43650 connector, and the enclosure carries an IP65 rating.
Yes. The DRG is manufactured in the USA, in Pittsburgh, Pennsylvania, and BABA (Build America, Buy America)–compliant versions can be specified. That suits equipment headed to government, municipal, and federally funded projects where domestic-content sourcing is preferred or required.