What Is the KOBOLD DPT Target-Type Flow Meter?
The KOBOLD DPT is a target-type flow meter that measures water flow from 1.5 to 500 GPM in 3/8" to 3" lines. It uses a unique target and leaf-spring system in a brass or stainless steel body, is rated to 580 PSIG and 176°F (80°C), and has an accuracy of ±3% of full scale.
A single leaf-spring both suspends the target and provides the resetting force. This simple, reliable design allows the meter to operate with virtually no wear, and the target plate measuring system offers a very low pressure loss. The DPT is available with 3-digit LED compact electronics or a 270° bar graph with 5-digit digital display, each with 4-20 mA output and switching outputs.
How the DPT Target-Type Flow Meter Works
Liquid flow deflects a target plate and lever arm against the leaf-spring. A permanent magnet on the lever arm and a Hall effect sensor inside the display unit convert the angular motion of the target into an electrical signal, which the electronics use for a flow rate display, adjustable setpoint switches, or an analog flow signal.
The magnet transfers the motion through the casing wall without contact, and press-fitted calibration nozzles adapt the meter to its measuring range.
DPT Flow Ranges, Line Sizes, and Connections
The DPT covers flow ranges from 1.5...8 GPM up to 225...500 GPM of water, with two ranges per line size. Line sizes run from 3/8" to 3", with NPT threaded fittings. LPM-scaled models are ordered by replacing the "G" in the model code with "H".
- 3/8": 1.5...8 GPM or 3...13 GPM
- 1/2": 1.5...8 GPM or 3...18 GPM
- 3/4": 1.7...14 GPM or 5...22 GPM
- 1": 5...17 GPM or 20...34 GPM
- 1-1/2": 15...45 GPM or 27...60 GPM
- 2": 22...118 GPM or 40...200 GPM
- 3": 175...396 GPM or 225...500 GPM
DPT Materials, Pressure Rating, and Temperature Rating
The DPT body is available in brass or in EN 1.4581 stainless steel, with a 316Ti stainless steel paddle, spring, and calibration nozzle. Brass models use NBR seals and stainless steel models use FKM seals. Maximum pressure is 580 PSIG (40 bar) at 70°F (21°C), and the process temperature range is -10 to 176°F (-23 to 80°C).
Maximum ambient temperature is 176°F (80°C), and the protection type is IP65.
DPT Display and Electronics Options
Two electronics packages are available. The compact electronics (DPT-..C3xx..) provide a 3-digit LED display, a 4-20 mA analog output (max. 500 Ω), and PNP or NPN semiconductor switching outputs on 24 VDC. The ADI electronics (DPT-..Kxx2..) provide a 270° bar graph with 5-digit digital display, 4-20 mA and 0-10 VDC outputs, and two relay changeover contacts.
- Compact electronics: 24 VDC ±20%, 3-wire technology, approx. 100 mA; one or two factory-set PNP or NPN switching outputs with programmable N/C or N/O contact operation; M12x1 (Micro-DC) plug connector.
- ADI electronics: 100...240 VAC ±10% or 18-30 VAC / 10-40 VDC supply; two relay changeover contacts rated max. 250 VAC / 5 A resistive load or max. 30 VDC / 5 A; pluggable terminal block via cable gland.
Installing the DPT Target-Type Flow Meter
The DPT mounts horizontally only, with flow in the direction of the arrow on the body. Straight piping of 10 pipe diameters is required at the inlet and 5 pipe diameters at the outlet. Flow direction must be specified for all configurations when ordering, and for horizontal flow the display is specified on top of the meter.
Inlet and outlet lines should be mechanically fixed 1.97" (50 mm) from the connections, avoiding pressure and tensile loads, with connections checked for leakage. A meter installed with an incorrect flow direction is not expected to function properly.
DPT Pressure Loss, Media, and Maintenance
Pressure loss at full-scale flow with water ranges from 0.15 psi (0.01 bar) on the two largest 3" models to 13.8 psi (0.95 bar) on the DPT-xx30 model. The meter requires no maintenance if the measured medium is not contaminated, and installing a filter, such as the KOBOLD MFR magnetic filter, is recommended.
- DPT-xx05: 10.7 psi; DPT-xx10: 11.3 psi; DPT-xx15: 12.5 psi; DPT-xx20: 9.4 psi
- DPT-xx25: 4.8 psi; DPT-xx30: 13.8 psi; DPT-xx35: 3.9 psi; DPT-xx40: 5.9 psi
- DPT-xx45: 2.2 psi; DPT-xx50: 4.1 psi; DPT-xx55: 0.30 psi; DPT-xx60: 2.3 psi
- DPT-xx65: 0.15 psi; DPT-xx70: 0.15 psi
The DPT is designed to measure liquids. Work on the sensor and electronics should be carried out only by the supplier; otherwise the guarantee is nullified.
Ordering the DPT Flow Meter
DPT model codes combine range, body material, fitting, and electronics; for example, DPT-1165G NB C34P is a brass 175...396 GPM meter with a 3" NPT fitting and compact electronics with 4-20 mA output and one PNP open collector.
Common Questions about DPT - Target-Type Flow Meter
Flow pushes a target plate on a lever arm against a flat leaf-spring. A magnet on the arm transfers that angular motion through the casing wall to a Hall effect sensor, with no contact and no losses. The sensor signal then drives the readout, the setpoint switches, and the analog output.
Measuring ranges in water run from 1.5...8 GPM on the smallest 3/8" meter to 225...500 GPM on the largest 3" meter, with two selectable ranges for every line size. LPM-scaled versions are ordered by substituting "H" for "G" in the model code.
Seven connection sizes are offered: 3/8", 1/2", 3/4", 1", 1-1/2", 2", and 3". Each size is supplied with NPT threads (fitting codes N3 through NB). The fitting code follows the range and material code in the part number, and the electronics code comes last.
The DPT is rated to 580 PSIG (40 bar) when the fluid is at 70°F (21°C). Process temperatures from -10°F (-23°C) up to 176°F (80°C) are permitted, and the ambient temperature may also reach 176°F (80°C). The enclosure carries IP65 protection.
The case is brass or EN 1.4581 stainless steel, a grade closest to CF8M cast or 316L wrought stainless. The paddle, spring, and calibration nozzle are 316Ti stainless steel, the magnet is ceramic oxide, and the seals are NBR on brass meters and FKM on stainless steel meters.
The C3xx compact electronics run on 24 VDC ±20% (3-wire, approx. 100 mA) and offer a 4-20 mA signal into a maximum load of 500 Ω plus one or two PNP or NPN semiconductor switches with programmable N/C or N/O operation. Connection is through an M12x1 Micro-DC plug.
The Kxx2 ADI electronics add a 270° bar graph beside a 5-digit digital readout, analog outputs of 4-20 mA and 0-10 VDC, and two relay changeover contacts rated to 250 VAC at 5 A resistive load, or 30 VDC at 5 A. Supply is 100...240 VAC, or alternatively 18-30 VAC / 10-40 VDC, with 4-button setup.
Install the meter in a horizontal line only, with the arrow pointing in the flow direction and the display on top. Allow straight pipe of 10 diameters upstream and 5 diameters downstream, fix the adjacent piping 1.97" (50 mm) away from each connection, and keep pressure and tensile loads off the body.
No routine maintenance is needed as long as the medium being measured is free of contamination. Fitting a filter upstream, for example KOBOLD's MFR magnetic filter, is recommended to avoid problems. Any work on the sensor or electronics must be done by the supplier, or the guarantee is nullified.
Pressure loss at full-scale water flow depends on the model, from 0.15 psi (0.01 bar) for DPT-xx65 and DPT-xx70 up to 13.8 psi (0.95 bar) for DPT-xx30. Other examples are 10.7 psi (0.74 bar) for DPT-xx05 and 4.1 psi (0.28 bar) for DPT-xx50.
Product Specifications
Measuring Range
1.5...8 GPM to 225...500 GPM
Fittings
3/8"...3" NPT Thread
Body Material
Brass, EN 1.4581 Stainless Steel
Max. Pressure
580 PSIG @ 70 °F
Media Temperature Range
-10...176 °F (80 °C)
Product Features
Target/Leaf-Spring Design
Accuracy ± 3% of Full Scale
Rate Display or Digital-Bargraph
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