Made in the USA Paddle-Wheel Flow Meter - DRH

The KOBOLD DRH is a paddle wheel flow sensor for water-like, low-viscosity liquids and aggressive chemical solutions, made in the USA with BABA compliant models available. It covers ten flow ranges between 0.05–0.2 GPM and 0.66–13.2 GPM through 3/8 inch or 1 inch NPT threads, with pressure ratings up to 1,450 PSIG and a maximum temperature of 176 °F (80 °C). According to the datasheet, the DRH is ideal for industrial or OEM applications, combining compact size, seven material combinations, and an economical price.

How the DRH Paddle Wheel Flow Sensor Works

The DRH employs permanent magnets embedded in a rotating paddle wheel. As liquid turns the wheel, a Hall-effect sensor detects each passing magnet and provides an output proportional to flow rate. Depending on the electronics ordered, that signal becomes a pulse frequency, a 4-20 mA analog value, switching contacts, or a displayed reading.

Flow Ranges, Fittings, and Ratings

According to specifications, the DRH spans 0.05–0.2 GPM at the low end to 0.66–13.2 GPM at the high end, with linearity of ±2.5% of full scale (±5% of full scale for the DRH-...F300 frequency version) and a sensor pressure drop of 14.5 PSI at 100% rated flow.

Process connections: 3/8 inch NPT or 1 inch NPT threads
Orifice diameters: 0.04–0.39 in (1–10 mm), matched to the calibrated range
Maximum pressure: 1,450 PSIG for DRH-12 and DRH-15; 230 PSIG for the other combinations
Maximum temperature: 176 °F (80 °C) for all material combinations
Output electrical protection: IP65

Seven Material Combinations

The datasheet lists seven material combinations, DRH-11 through DRH-19, so the wetted parts can be matched to the liquid. Housings come in brass, 316L stainless steel, POM, or PVDF; housing covers in acrylic, brass, 316L stainless steel, POM, or PVDF; O-rings in NBR or FKM. Every version uses a PTFE paddle and axle support with a ceramic axle.

Output and Electronics Options

The DRH can be supplied with a frequency output, a 4-20 mA analog output, or a compact electronics package that provides an LED display, an adjustable (0)4-20 mA output, and programmable setpoint switches. Counter and dosing electronics with an LCD and two relays are also listed in the order table.

Frequency output (..F300): PNP open-collector pulse, max. 25 mA, 12-28 VDC supply; a frequency divider version (..F390) is factory set from 1 to 1/128
Analog output (..L342, ..L343, ..L442): 4-20 mA in 2-wire or 3-wire form, max. load 500 Ω, with M12x1 or DIN 43650 connection; an AUF-1000/AUF-1001 plug-on display is available for the DIN-plug version
Compact electronics (..C34P, ..C30R): 24 VDC ±20% supply, PNP or NPN switching, N/C or N/O contact operation, set with two buttons
Counter (..E14R, ..E34R) and dosing (..G14R, ..G34R) electronics: illuminated LCD, adjustable (0)4-20 mA output, and two relays rated 30 VAC/DC, 2 A, 60 VA

Installation and Maintenance

According to the manual, straight inlet and outlet pipe runs are not required. The housing must stay filled with the liquid at all times, flow must move in the direction of the arrow on the unit, and the rotor axle must sit in the horizontal plane. When the medium is clean, the manual notes that maintenance needs stay minimal.

Flow Direction Specification May Be Required

Important: This flow meter (model dependent) may require flow direction specification to complete your order. While our product number identifies the meter's core specifications, flow direction is a critical parameter for certain models that must be specified separately to ensure proper performance and installation.

Why Flow Direction Matters

Flow meters are precision instruments engineered with internal components optimized for fluid movement in a specific direction, for certain models. Installing a meter that requires flow direction with an incorrect flow direction will not allow it to function properly.

What We Need From You

Please read the datasheet order table carefully (including any asterisks) and if your model requires a flow direction please specify your desired flow direction, in addition to your part number, when placing your order. Flow directions are option/model-dependent but may include the following choices: Top to Bottom, Bottom to Top, Left to Right, Right to Left. We cannot process orders without the required flow direction specification, if it is needed. Orders submitted that are missing this information are likely to experience delays in processing. If you're unsure of your flow direction, our technical team is ready to assist you in determining the correct specification based on your system requirements at 412-788-2830 or customerservice@koboldusa.com.

Common Questions about DRH - Paddle Wheel Flow Sensor

The operating manual classifies the DRH as a rotating vane flow meter for measuring and monitoring liquids of low viscosity. A magnet fitted in the vane, hermetically sealed from the medium, transfers rotary motion without contact to a Hall-effect sensor, which converts it to a frequency signal for the connected electronics.

The order table lists ten calibrated ranges, from 0.05–0.2 GPM up to 0.66–13.2 GPM. Meters with 3/8 inch NPT threads use orifice diameters of 1, 2, 3, 5, or 7 mm, while the 1 inch NPT versions use orifice diameters of 2, 3, 5, 9, or 10 mm.

Ratings depend on the material combination: DRH-12 (all-brass) and DRH-15 (all-316L stainless steel) handle up to 1,450 PSIG, while the remaining five combinations handle up to 230 PSIG. Every combination is rated to 176 °F (80 °C), and the published pressure drop is 14.5 PSI at full rated flow.

Seven combinations, numbered DRH-11 through DRH-19, are listed in the datasheet. Housing options are brass, 316L stainless steel, POM, and PVDF; cover options are acrylic, POM, PVDF, brass, and 316L stainless steel; O-rings are NBR or FKM. All versions share a PTFE paddle, a PTFE axle support, and a ceramic axle.

Available outputs include a PNP open-collector pulse frequency signal (maximum 25 mA), a factory-set frequency divider version, and 4-20 mA analog in 2-wire or 3-wire form with a 500 Ω maximum load. Compact, counter, and dosing electronics add displays, adjustable (0)4-20 mA outputs, transistor switches, or relays.

The frequency output version operates on 12-28 VDC and consumes about 10 mA. The frequency divider, analog, compact, counter, and dosing versions require 24 VDC ±20%, consuming approximately 15 mA to 150 mA depending on the electronics. Electrical protection for the output electronics is IP65.

A part number such as DRH-1460N6 L343 strings together the material combination (11 through 19), the range code, the thread size (N3 for 3/8 inch NPT, N6 for 1 inch NPT), and the electronics code. Per the datasheet, specify flow direction for any meter configured with a Compact, Counter, or Dosing electronic option.

Ensure the instrument housing remains continuously filled with the flow medium, especially for flows from top to bottom; no straight lengths are necessary at the inlet and outlet connections. Check that flow follows the arrow on the front of the unit, avoid pressure and tensile loads, and mechanically secure the piping 1.97 in (50 mm) from the connection.

Yes. The product page lists the DRH as Made in the USA, and BABA (Build America, Buy America) compliant models are available. KOBOLD states that it offers many BABA-compliant flow and level products and is committed to producing high quality American made products.

With clean media, the manual describes the DRH as virtually maintenance-free. Guard against ferritic (iron metal) contamination, which can be eliminated with a magnetic filter such as the KOBOLD model MFR. The sensor can be opened for cleaning, but work on the sensor and electronics should only be carried out by the manufacturer.