Impeller Paddle Wheel Flow Meter – DPE

The KOBOLD DPE is a paddle wheel flow meter for liquids in pipes up to 3 inches in diameter, with six measuring ranges from 1.5 to 8 GPM up to 15 to 200 GPM, a maximum operating pressure of 580 PSIG, and a maximum process temperature of 176°F (80°C). Its impeller protrudes only minimally into the flow stream, which keeps head loss low. Threaded bodies are brass or 316 stainless steel, ½" to 3" NPT, with pulse, 4-20 mA, switch, display, totalizing, or batching electronics.

Measuring accuracy is ±2.5% of full scale.

How the DPE Paddle Wheel Flow Meter Works

The DPE works on the paddle wheel principle. A six-vane wheel, held axially in a bearing, is set in motion by the flowing liquid. Hermetically sealed permanent magnets in the blade tips generate electrical pulses in a Hall effect sensor mounted outside the flow area. That output becomes a linear pulse or 4-20 mA signal; optional displays and controllers add local flow rate indication and programmable setpoint switches.

Flow Ranges, Pipe Sizes, and Ratings

Each measuring range is matched to one NPT size and offered in brass or stainless steel. The 580 PSIG rating applies at 68°F (40 bar at 20°C), process and ambient temperature limits are both 176°F (80°C), and the enclosure is rated IP65.

½" NPT: 1.5 to 8 GPM (5.7 to 30.3 L/min), DPE-1150 brass / DPE-1250 stainless steel
¾" NPT: 3 to 13 GPM (11.4 to 49.2 L/min), DPE-1155 / DPE-1255
1" NPT: 5.5 to 20 GPM (20.8 to 75.7 L/min), DPE-1160 / DPE-1260
1½" NPT: 6.6 to 65 GPM (25.0 to 246 L/min), DPE-1165 / DPE-1265
2" NPT: 8 to 90 GPM (30.3 to 341 L/min), DPE-1170 / DPE-1270
3" NPT: 15 to 200 GPM (56.8 to 757 L/min), DPE-1175 / DPE-1275

Maximum pressure loss: ½" 0.73 psi (50 mbar); ¾" and 1" 0.44 psi (30 mbar); 1½" 0.58 psi (40 mbar); 2" 0.29 psi (20 mbar); 3" 0.15 psi (10 mbar). Exceeding the measuring range damages the bearings and causes significant measurement error.

Materials of Construction

The DPE housing is brass or 316 stainless steel. The brass version uses NBR seals and the stainless steel version uses FKM seals. Both use a PVDF paddle wheel, carbide axle, and bearing.

Output and Electronics Options

Every DPE is ordered with one of five electronics families. Pulse, analog, and compact versions use M12x1 or DIN 43650 plug connectors; ADI-1 and ZED versions use pluggable terminal blocks.

Frequency output (..F300): 12-28 VDC, 10 mA, PNP open collector pulse output, max. 25 mA. The ..F390 adds a factory-set frequency divider of 1 to 1/128 (24 VDC ±20%, 15 mA).
Analog output (..L342, ..L343, ..L442): 24 VDC ±20%, 4-20 mA in 2-wire or 3-wire form, max. load 500 Ω. The ..L442 accepts an optional AUF plug-on LED display.
Compact electronics (..C3xx): LED display, adjustable 4-20 mA output, one or two PNP or NPN switching outputs (factory set, N/C or N/O programmable), 24 VDC ±20% three-wire at approx. 100 mA.
ADI-1 rate and totalizing electronic (..K042, ..K342): 270° bargraph with 5-digit display, 4-20 mA and 0-10 VDC outputs, two changeover relays rated max. 250 VAC / 5 A resistive or 30 VDC / 5 A, 100 to 240 VAC ±10% (..K042) or 18 to 30 VAC / 10 to 40 VDC (..K342).
ZED totalizing electronic (..E34R): illuminated 2 × 8-digit LCD with grand total, resettable total, and selectable units, adjustable 4-20 mA output (max. 500 Ω), two relays rated max. 250 V / 5 A / 1000 VA, MIN/MAX memory, 24 VDC ±20% at approx. 170 mA.
ZED batching electronic (..G34R): as ..E34R, with a scalable 4-20 mA output and batching functions (start, stop, fine batching, correction amount, flow switch).

Installation Requirements

Install the DPE with flow in the direction of the arrow; mounting position is universal. Upstream straight pipe runs from 15 × D after a reduction to 50 × D after a control valve, with 5 × D downstream. Avoid pressure and tension loads on the body and check the connections for leaks.

Use supply wires of at least 0.25 mm² and wire with the supply de-energized; incorrect wiring damages the electronics. Flow direction must be specified at order for any compact, ADI-1, or ZED version. The DPE is maintenance free in fluids that do not leave deposits, and an upstream filter is recommended to help prevent contamination.

Common Questions about DPE - Paddle-Wheel Flow Meter

The DPE spans 1.5 GPM on the smallest ½" NPT model to 200 GPM on the 3" NPT model. Each pipe size carries its own range: ½" covers 1.5 to 8 GPM, ¾" 3 to 13, 1" 5.5 to 20, 1½" 6.6 to 65, 2" 8 to 90, and 3" 15 to 200.

The DPE is accurate to ±2.5% of full scale, stated as one value for the whole series regardless of size or electronics. Full scale is the upper limit of the range ordered, for example 8 GPM on a ½" NPT DPE-1150 or 200 GPM on a 3" NPT DPE-1175.

The maximum operating pressure is 580 PSIG (40 bar), a rating that applies at 68°F (20°C). The process temperature limit is 176°F (80°C), and the ambient temperature limit is also 176°F (80°C). The enclosure carries IP65 protection, and the same limits apply to both the brass and stainless steel versions.

Material options are a brass body with NBR seals or a 316 stainless steel body with FKM seals. Both versions share a PVDF paddle wheel and a carbide axle. The magnets that drive the Hall effect sensor are hermetically sealed inside the wheel blades.

Depending on the electronics ordered, the DPE provides a PNP open collector pulse output, a 2-wire or 3-wire 4-20 mA signal, PNP or NPN switching outputs, a 0-10 VDC output, or relay contacts, with LED or LCD readouts on the compact, ADI-1, and ZED versions. An AUF plug-on display suits the ..L442 analog version.

Supply voltage depends on the electronics: 12-28 VDC for the ..F300 frequency output; 24 VDC ±20% for the ..F390, analog, compact, and ZED versions; and 100-240 VAC, 18-30 VAC, or 10-40 VDC for the two ADI-1 versions. Current draw runs from 10 mA on the ..F300 to approx. 170 mA on ZED units.

Upstream straight run is set by what sits ahead of the meter: 15 pipe diameters after a reduction, 18 after an expansion, 20 after a single elbow or tee, 25 after two elbows, 40 after two elbows in three dimensions, and 50 after a control valve. Downstream, 5 pipe diameters is sufficient in every arrangement.

Yes, for any DPE ordered with compact, ADI-1, or ZED electronics. Choose top to bottom, bottom to top, left to right, or right to left as seen facing the meter. For vertical flow with ADI-1 or ZED electronics, state whether the display goes on the left or right side. Orders missing this information are likely to be delayed.

No scheduled maintenance is needed when the liquid does not leave deposits. Where deposits are possible, an upstream filter such as the KOBOLD MFR magnetic filter is recommended. If cleaning is needed, the sensor can be opened; the wheel must be reinstalled in the correct position and orientation, and electronics work must be performed by KOBOLD.