The KOBOLD DVH is a multivariable vortex flow meter that measures the mass flow rate of gases, liquids and steam from a single pipe penetration. It can be equipped with up to three primary sensing elements: a vortex-shedding velocity sensor, an RTD temperature sensor and a solid-state pressure transducer, so velocity, temperature and pressure are all measured at one location.
Why One Measurement Location Matters
Systems that use external process measurements may not provide adequate compensation when process conditions change radically between the point of velocity measurement and the point where upstream or downstream pressure and temperature are taken. Because the DVH measures all of these parameters in a single location, it is designed to deliver a more accurate process measurement.
A single line penetration with multivariable output also simplifies system complexity and helps reduce equipment, installation and maintenance costs.
DVH Versions: Volumetric, Temperature Compensated, Multivariable and Energy
Five DVH versions are available. The DVH-V measures volumetric flow of liquids, gas or steam. The DVH-T adds a temperature sensor, the DVH-P adds temperature and pressure sensors, and the DVH-E and DVH-M add energy consumption measurement. All versions share a 316L stainless steel flow body.
- DVH-V: a direct reading of volumetric flow rate, generally the most cost-effective choice for liquid flow monitoring, in applications ranging from general water flows to hydrocarbon fuel flow measurement.
- DVH-T: a 1000 Ω platinum RTD that can be used to calculate and output a compensated mass reading.
- DVH-P: flow computer functionality in a compact field device, with up to three analog outputs selected from volumetric flow, mass flow, temperature, pressure and density.
- DVH-E and DVH-M: real-time energy consumption calculation (not approved for custody transfer).
Accuracy, Repeatability and Turndown
Volumetric flow accuracy is ±0.7% of rate for liquids and ±1% of rate for gas and steam. Mass flow accuracy is ±1% of rate for liquids and ±1.5% of rate for gas and steam, based on 50 to 100% of the pressure range. Turndown is application dependent and can exceed 100:1.
Temperature accuracy is ±2 °F (±1 °C), pressure ±0.3% of full scale, and density ±0.3% of reading for liquids and ±0.5% for gas and steam. Repeatability is ±0.2% of rate for mass flow and ±0.1% of rate for volumetric flow.
Flow Ranges, Pipe Sizes and Connections
The DVH is available in ½ to 8 inch (DN 15 to DN 200) ANSI 150, 300 or 600 lb flanged sizes and ½ to 4 inch wafer sizes. Water ranges run from 0.9 to 22 GPM (0.2 to 5 m³/h) in ½ inch up to 142 to 4,270 GPM (32 to 970 m³/h) in 8 inch.
Air covers 1.8 to 203,000 SCFM and saturated steam 6.5 to 380,148 lb/h. Liquid velocity is 1 to 30 ft/s (0.3 to 9 m/s); gas and steam velocity is up to 300 ft/s (90 m/s).
Temperature and Pressure Ratings
Three process temperature versions are available: standard, rated -40 to 500 °F (-40 to 260 °C); high temperature, up to 750 °F (400 °C); and low temperature, down to -328 °F (-200 °C). Ambient temperature is -40 to 140 °F (-40 to 60 °C). Maximum pressure is 1450 psia (100 bar abs).
Models with a pressure sensor are offered with full scale ranges of 30, 100, 300, 500 or 1,500 psia (2, 7, 20, 35 or 100 bar abs); specify the lowest full scale range that covers the application to maximize accuracy.
Power Supply, Display and Enclosure
The DVH-V is loop powered from 12 to 36 VDC. The DVH-P takes a 12 to 36 VDC, 4-wire supply or an 85 to 240 VAC, 50/60 Hz supply. The alphanumeric 2-line, 16-character LCD display rotates in 90° steps, and six buttons provide full field configuration of ranges, outputs and display.
The NEMA 4X and IP66 cast enclosure may be used indoors or outdoors, and the electronics mount directly on the flow body or remotely with a standard 5 m (16.4 ft) cable, 15 m (49.2 ft) maximum.
Installation Requirements
The DVH installs between two conventional pipe flanges of the same nominal size, with the flow arrow pointing in the direction of flow. Minimum straight run is 10 pipe diameters upstream and 5 downstream after one 90° elbow, 15 upstream after two elbows, and 25 upstream after two out-of-plane elbows or a partially open valve.
A reduction before the meter requires 10 diameters upstream and an expansion 20, each with 5 downstream.
Insertion Alternative: DVE Multivariable Vortex Flow Meter
For insertion installations in 2 inch and larger lines, KOBOLD offers the DVE insertion multivariable vortex flow meter, which is designed to offer the same capabilities as the DVH. Visit our in-depth article on vortex flow meters to learn more about the vortex principle of operation and its advantages and limitations.
Common Questions about DVH - Multivariable Vortex Flow Meter
Frequently Asked Questions About the DVH
A specially shaped bluff body sits directly in the flow path. At specific flow velocities the bluff body sheds vortices, and the small pressure differences they create are sensed by a piezoelectric sensor located directly behind it. The number of vortices detected is directly proportional to flow velocity, and the flow computer calculates mass flow from velocity, temperature and pressure.
Yes. The DVH-T, typically used for saturated steam, uses its RTD temperature input to output a compensated mass reading. The DVH-P adds pressure sensing for compensated mass flow of steam, gases and liquids. Saturated steam ranges start at 6.5 to 52 lb/h in ½ inch at 5 psig and reach 6,014 to 380,148 lb/h in 8 inch at 500 psig.
Volumetric meters provide one 4-20 mA analog output, one totalizer pulse and HART protocol. Multivariable meters provide up to three 4-20 mA signals, three alarms, one totalizer pulse and HART, with Modbus process monitoring as an option. Alarms are solid-state relays rated 40 VDC, and the totalizer pulse is a 50 ms pulse at 40 VDC.
Yes. Mounting position has no effect on the in-line DVH. For liquids, locate the meter where the pipe is always full, and in vertical lines install it with flow upward where possible. On horizontal lines above 300 °F (150 °C), mount the meter at a 45 or 90 degree angle to avoid overheating the electronics enclosure.
The meter inside diameter equals the nominal pipe inside diameter in schedule 80; a 2 inch meter has an ID of 1.939 in. (49.35 mm). Do not install the meter in a pipe whose inside diameter is smaller than the meter bore. Schedule 160 and heavier pipe requires a special meter, so consult the factory before purchasing.
Any gas, liquid or steam compatible with 316L stainless steel. Vortex flow meters are not suitable for two-phase flows such as liquid and gas mixtures. Unless optional oxygen cleaning is ordered, the meter may not be fit for oxygen service. A 3.1 material certificate, NACE conformance and oil and fat free cleaning of the wetted parts are available as options.
ATEX: II 2 G Ex d IIB + H2 T6 and II 2 D Ex tD A21 IP66 T85 °C, Ta = -40 °C to +60 °C. IECEx: Ex d IIB + H2 T6 and Ex tD A21 IP66 T85 °C, Ta = -40 °C to +60 °C. Certified flameproof cable entries are required to maintain the rating.
Confirm installation direction, power and wiring, the application fluid, the meter range and configuration, and the upstream and downstream pipe geometry. An output at no flow means the low flow cutoff is set too low; raise it until the output stops. No output can mean the cutoff is set too high; lower it until a steady reading appears.
Yes, with the DVH-E or DVH-M energy monitoring option. The meter is programmed for steam, hot water or chilled water, monitors one side of the process (sent or return), and uses a second separate temperature sensor on the opposite side to calculate the change in energy. Selectable units include BTU, joules, calories, watt-hours, megawatt-hours and horsepower-hours.
Yes. To ensure proper operation, the DVH requires a completed Application Guide submitted with any order, unless it is a repeat order of a previously specified product. The guide records fluid type, pipe size and schedule, minimum, nominal and maximum flow, temperature, pressure, density and viscosity, plus version, flange size and rating, power supply and output options.